Lukas Chrostowski

Professor

Research Interests

silicon photonics
biosensors
biophotonics
quantum computing
optoelectronics
photonics
optics
semiconductor lasers

Relevant Degree Programs

 

Research Methodology

electron beam lithography

Recruitment

Complete these steps before you reach out to a faculty member!

Check requirements
  • Familiarize yourself with program requirements. You want to learn as much as possible from the information available to you before you reach out to a faculty member. Be sure to visit the graduate degree program listing and program-specific websites.
  • Check whether the program requires you to seek commitment from a supervisor prior to submitting an application. For some programs this is an essential step while others match successful applicants with faculty members within the first year of study. This is either indicated in the program profile under "Requirements" or on the program website.
Focus your search
  • Identify specific faculty members who are conducting research in your specific area of interest.
  • Establish that your research interests align with the faculty member’s research interests.
    • Read up on the faculty members in the program and the research being conducted in the department.
    • Familiarize yourself with their work, read their recent publications and past theses/dissertations that they supervised. Be certain that their research is indeed what you are hoping to study.
Make a good impression
  • Compose an error-free and grammatically correct email addressed to your specifically targeted faculty member, and remember to use their correct titles.
    • Do not send non-specific, mass emails to everyone in the department hoping for a match.
    • Address the faculty members by name. Your contact should be genuine rather than generic.
  • Include a brief outline of your academic background, why you are interested in working with the faculty member, and what experience you could bring to the department. The supervision enquiry form guides you with targeted questions. Ensure to craft compelling answers to these questions.
  • Highlight your achievements and why you are a top student. Faculty members receive dozens of requests from prospective students and you may have less than 30 seconds to peek someone’s interest.
  • Demonstrate that you are familiar with their research:
    • Convey the specific ways you are a good fit for the program.
    • Convey the specific ways the program/lab/faculty member is a good fit for the research you are interested in/already conducting.
  • Be enthusiastic, but don’t overdo it.
Attend an information session

G+PS regularly provides virtual sessions that focus on admission requirements and procedures and tips how to improve your application.

 

Master's students
Doctoral students
Postdoctoral Fellows
Any time / year round

silicon photonic device and circuit design, nanofabrication, quantum computing, single photon devices

I support public scholarship, e.g. through the Public Scholars Initiative, and am available to supervise students and Postdocs interested in collaborating with external partners as part of their research.
I support experiential learning experiences, such as internships and work placements, for my graduate students and Postdocs.
I am open to hosting Visiting International Research Students (non-degree, up to 12 months).
I am interested in hiring Co-op students for research placements.

Graduate Student Supervision

Doctoral Student Supervision (2008-2018)
Enabling practical deployment of silicon ring resonator-based systems (2018)

The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.

https://open.library.ubc.ca/collections/24/items/1.0363058

Silicon photonic switches for optical communication applications (2017)

Optical switches are used for signal switching in optical communication networks. Silicon photonics is a low-cost and mature technology to develop high-performance optical switches. This thesis is a theoretical and experimental study on silicon photonic switches, featuring broadband, low-power, high-speed, and low-crosstalk performance.Broadband 3-dB couplers are fundamental building blocks for broadband switches based on Mach-Zehnder interferometer (MZI) structures. A broadband 3-dB coupler, which has a 100 nm operation bandwidth with coupling imbalance being much less than its competitors, i.e., adiabatic couplers and multimode interference couplers, has been theoretically designed and experimentally demonstrated.Switches using thermo-optic phase tuning typically have high power consumption. In this thesis, two methods to improve the tuning efficiency of thermo-optic phase shifters have been investigated and employed: 1) using thermal isolation structures and 2) using folded waveguides structures. Accordingly, thermo-optic switches with state-of-the-art, ultra-low power consumption of down to 50μW/π have been demonstrated.MZI switches using carrier injection phase tuning have high-speed performance but with a large switching crosstalk, due to the imbalanced tuning loss in the MZI structure. A novel carrier injection switch based on a balanced nested Mach-Zehnder interferometer (BNMZI) structure has been theoretically proposed. The BNMZI switch has balanced tuning schemes and therefore can be both high-speed and crosstalk-free. Besides, the switch has three switching states: cross, bar, and blocking.Polarization control is necessary for single-mode switches. A high-performance polarization beamsplitter (PBS), which has a 120 nm operation bandwidth with modal isolations of more than 20 dB, has been designed and demonstrated, and it can be used for polarization control for single-mode switches.Characterizing fabrication variability and performing yield prediction for photonic integrated circuits (PICs) are both challenging for photonics designers. We have developed an accurate and cost-efficient characterization method for fabrication variations, which extracts waveguide dimension variations from the spectral response of a single racetrack resonator. In addition, we have proposed a novel yield prediction method for PICs, which, for the first time in silicon photonics, is able to model the impacts of layout-dependent correlated manufacturing variations and take them into account in circuit simulations.

https://open.library.ubc.ca/collections/24/items/1.0355828

Sub-wavelength grating components for silicon-on-insulator platform (2017)

This dissertation is a theoretical and experimental study of sub-wavelength grating (SWG) based photonic devices for the silicon-on-insulator (SOI) platform, including high-efficiency sub-wavelength grating couplers (SWGCs), broadband SWGCs, broadband SWG directional couplers, and an SWG polarization splitter-rotator. High-efficiency SWGCs with improved operating bandwidths and sup- pressed back reflections have been demonstrated to couple light into and out of SOI based photonic integrated circuits (PICs). One-dimensional SWGs have been proposed and experimentally demonstrated for the first time to make fully-etched grating couplers, which have performances comparable to the state-of-the-art fully-etched grating couplers, but with better fabrication tolerance, reduced fabrication complexity, and less cost. A theoretical study of the operating bandwidths for grating couplers has been presented and a design methodology has been demonstrated for designing SWGCs with design-intent operating bandwidths. SWGCs with 1-dB bandwidths up to 90 nm have been demonstrated, which have improved the operating bandwidth of fully-etched grating couplers by a factor of 3. Such broadband SWGCs are essential components for applications such as wavelength-division multiplexing (WDM) PICs and bio-sensing. Compact directional couplers, with dimensions about 10 times smaller than its alternatives, i.e., adiabatic couplers and multimode interference couplers have been demonstrated for various power splitting ratios. The operating bandwidths of our directional couplers have been improved by a factor of 2 as compared to conventional directional couplers. The dispersion properties of SWGs have been explored and applied to engineer the wave- length dependancy of conventional directional couplers for broad operating bandwidths, which is the first experimental demonstration of such devices. Polarization splitter and polarization rotators are essential components to address the polarization diversity of PICs. An ultra-compact mode- coupling based polarization splitter-rotator (PSR), which combines functionalities of a polarization splitter and a polarization rotator, with dimensions 15-20 times smaller than its alternative, i.e., mode-evolution based PSRs, has been experimentally demonstrated for the first time, where an asymmetric waveguide system consisting of a strip waveguide and an SWG waveguide were used to improve the fabrication tolerance of such devices. A measured peak polarization conversion efficiency of −0.3 dB with crosstalks below −10 dB over the C-band has been achieved.

https://open.library.ubc.ca/collections/24/items/1.0340496

A microfluidic platform to study real-time tumour cell and tumour spheroid response to chronic and transient hypoxia (2016)

Cell-based screening of cancer treatments is used early in the drug development process to test the efficacy and toxicity of treatment candidates prior to animal and human testing. Current cell-based screening methods offer limited predictive capacity, contributing to the high percentage of drugs that fail during the clinical trial stage (80-95% for cancer treatments). One shortcoming of traditional cell-based screening platforms is their inability to recreate many aspects of the natural environment of tumour cells, which can affect treatment response. One important aspect of the microenvironment that can affect cell behaviour and treatment response is oxygenation. Irregular blood vessel formation can cause tumour oxygenation to be much lower than that of surrounding tissue, and spatial and temporal variations in oxygen can be present. Temporal variations can occur at timescales up to several cycles/hour: changes that are too fast to recreate using standard technologies like well plates due to their long diffusion distances. This thesis presents a novel microfluidic platform to expose cells to both chronic and time-varying oxygen profiles and study their response. Microfluidics technology is combined with 3-D cell culture in tumour spheroids, which can better recreate other aspects of the tumour microenvironment (such as cell-cell and cell-matrix interactions) than traditional 2-D culture. The functionality of the oxygen control device is verified using both finite-element modelling and integrated optical oxygen sensors. Two novel methods for oxygen sensor microfabrication are presented, and the functionality of sensors during long-term experiments is studied. Precise oxygen control is demonstrated using the microfluidic system, with oxygen switching times of
https://open.library.ubc.ca/collections/24/items/1.0303474

High performance silicon photonic filters for dense wavelength-division multiplexing applications (2016)

This dissertation presents theoretical and experimental results for silicon optical ring resonator filters that meet many of the typical commercial specifications for dense wavelength-division multiplexing (DWDM) filters. First, we theoretically demonstrate a silicon quadruple Vernier racetrack resonator that meets 4-port filter commercial specifications for a clear window of 0.08 nm and a channel spacing of 0.8 nm while being tolerant to typical fabrication variations. Next, we experimentally demonstrate a silicon quadruple Vernier racetrack resonator that meets many 3-port filter commercial specifications for a clear window of 0.048 nm and a channel spacing of 0.8 nm. Then, enhanced resonant tuning range using the Vernier effect is theoretically and experimentally demonstrated using a thermally tunable silicon quadruple Vernier racetrack resonator. Also, we sent 12.5 Gbps data through a thermally tunable silicon quadruple Vernier racetrack resonator and show open eye diagrams in both the drop port and through port of the filter, even within one of the minor through port notches. We then present theoretical and experimental results on a high performance silicon double microring resonator filter using Mach-Zhender interferometer-based coupling that meets numerous 3-port filter commercial specifications for a clear window of 8 GHz and a channel spacing of 200 GHz as well as having an FSR larger than the span of the C-band and low through port passband dispersion. Next, we present a FSR-eliminated silicon Vernier racetrack resonator filter. We demonstrate the performance of this filter both theoretically and experimentally. The FSR of this filter is eliminated by using contra-directional grating couplers (contra-DCs) to suppress all but one of the notches and peaks of the filter's spectra. Lastly, a process calibration procedure is demonstrated that accurately determines the coupling coefficients of fabricated contra-DCs and is used to design a FSR-eliminated silicon Vernier racetrack resonator filter that meets 3-port filter commercial specifications for a clear window of 13 GHz and a channel spacing of 200 GHz. This filter also has low drop port dispersion and low dispersion within the passbands of the through port.

https://open.library.ubc.ca/collections/24/items/1.0300138

Feasibility of optical gyroscopic sensors in silicon-on-insulator technology (2015)

In the last decade, silicon photonics has become a strategic technology for the development of telecommunications and sensors. Due to its compatibility with well-developed complementary metal oxide semiconductor (CMOS) fabrication processes, silicon on insulator (SOI) wafers can be processed to create thousands of devices per die in a fast and inexpensive way. Being solid state devices with no movable parts, optical gyroscopes have longer life expectancies and shock resistance compared to micro-electro-mechanical gyroscopes. Thus, the implementation of SOI-based gyroscopes is desirable for large-scale, low-cost production. This thesis presents a study of the feasibility of implementing optical gyroscopes in SOI technology. A comprehensive theoretical study has been carried out to develop a device-level optimization and robustness analysis, showing that the most crucial resonator parameter is the propagation loss, followed by length and coupling. For a given propagation loss, there is an optimal resonator size, beyond which the angular speed resolution is severely degraded. On the system level, the impact of signal-to-noise ratio and insertion loss on the resolution are described.Given that the propagation loss is the most important parameter, strategies were proposed to reduce it as much as possible while still using CMOS-compatible processes. The quality factor, Q was chosen as the figure of merit to be maximized during the design iterations. As a result, the largest Q factors reported to date on SOI, using standard CMOS-compatible processes, were achieved. These Q factors are comparable to, or exceed, those of optical resonators intended for gyroscopic applications that are fabricated in materials such as indium phosphide (InP). Innovative approaches to compensate for fabrication variations are proposed, such as thermally-tuneable coupling and reference rings for differential measurements. Complex mechano-opto-electrical measurement setups were designed and implemented to characterize SOI gyroscopes, both at rest and under rotation. As a result, the Microsystem Integration Platform for Silicon-Photonics (Si-P MIP) was created. This characterization platform is now being commercialized by CMC Microsystems for academic and industrial applications. The main practical and theoretical challenges regarding the implementation of optical ring gyroscopes on SOI have been identified. Schemes to address them and suggestions for future work are proposed.

https://open.library.ubc.ca/collections/24/items/1.0166645

Optical resonator sensors and systems (2015)

Silicon-on-insulator (SOI)-based sensors are attractive for sensing applications in environmental safety, oil and gas, medical research, and clinical applications. Since these devices are typically developed using Complementary metal-oxide-semiconductor (CMOS)-compatible multi-project-wafer (MPW) shuttles, they bring the potential for having sensing systems on chips (SSOCs), and for mass fabrication and low cost production. The objective of this thesis is to improve the sensitivity, accuracy, and repeatability of sensors fabricated on the SOI platform. Such sensors have the potential to be the key components of an SSOC.One can increase the sensitivity of a resonator sensor by increasing the interaction between the evanescent field of the guided mode and the analyte. In this thesis, two methods for increasing this interaction in micro-ring resonator-based sensors are investigated: 1) using the transverse electric (TE) guided mode in ultra-thin strip waveguides and 2) using the quasi-transverse magnetic (TM) guided mode in thin strip waveguides. Using analyses and simulations, micro-ring sensors were designed to be fabricated within the constraints of a MPW CMOS-compatible process. Using the TE sensors, the temperature-induced errors were reduced by a factor of three; and the TM sensors exhibited twice the sensitivity of the best SOI micro-ring resonator-based sensors reported to date.Moving towards the actual implementation of an SSOC, a system of sensors was design to correct for unwanted variations in the measurements. This system drew on multivariate techniques to achieve improvements that resulted in measurements that were more repeatable and more accurate in the presence of environmental variations. The capability of this system is investigated by designing a cascade of previously developed micro-ring sensors with various waveguide thicknesses. With this system of sensors, we achieved an R2 value of predictions over 0.996 in the presence of a 2 K temperature drift. This approach significantly improved the repeatability and reliability of the measurements in the presence of undesirable variations and drifts. In another move towards achieving an SSOC, integrating photodetectors in resonator sensors was investigated. To accomplish this, ion-implantation on micro-ring sensors was used. Such integrated photodetector-sensors were designed, fabricated, and tested. Their measured sensitivities were within 90% of the expected values.

https://open.library.ubc.ca/collections/24/items/1.0166188

Silicon photonic waveguide Bragg gratings (2014)

Silicon is the most ubiquitous material in the electronics industry, and is now expected to revolutionize photonics. In just over ten years, silicon photonics has become a key technology for photonic integrated circuits. By taking advantage of silicon-on-insulator (SOI) wafers and the existing complementary metal-oxide semiconductor (CMOS) fabrication infrastructure, silicon photonic chips are now being delivered with low cost and rapidly increasing functionality.This thesis presents the integration of a fundamental optical device - Bragg grating - into SOI waveguides. Various types of waveguides and grating structures have been investigated. All designs are fabricated using CMOS foundry services. We have also explored various applications using the fabricated devices.From the beginning, we focused on strip waveguide uniform gratings, as these are the most simple to design and fabricate. We have studied many design variations, supported by experimental results. In parallel, we have provided insight into practical issues and challenges involved with the design, fabrication, and measurement, such as the lithography effects, thermal sensitivity, and wafer-scale nonuniformity. We then introduce phase-shifted gratings that can achieve very high quality factors and be employed in various applications. We have also demonstrated sampled gratings and the Vernier effect in strip waveguides.To obtain narrow-band gratings, we propose the use of a rib waveguide. We also propose a multi-period grating concept by taking advantage of the multiple sidewalls of the rib waveguide, to increases the design flexibility for custom optical filters. The wafer-scale data shows that rib waveguide gratings have better performance uniformity than strip waveguide gratings, and that the wafer thick- ness variation is critical. Additionally, we have demonstrated very compact Bragg gratings using a spiral rib waveguide.Finally, we demonstrate slot waveguide Bragg gratings and resonators, which has great potential for sensing, modulation, and nonlinear optics. We have also developed a novel biosensor using a slot waveguide phase-shifted grating that has a high sensitivity, a high quality factor, a low limit of detection, and can interrogate specific biomolecular interactions.

https://open.library.ubc.ca/collections/24/items/1.0165738

Silicon photonic filters for wavelength-division multiplexing and sensing applications (2012)

This thesis is a theoretical and experimental study of novel silicon photonic filters, such as traveling-wave resonators (TWRs) and grating-assisted, contra-directional couplers (contra-DCs), for on-chip wavelength-division-multiplexing (WDM) systems and sensing applications. To measure optical losses of photonic components such as Y-branch splitters and waveguide crossings, we have developed a ring-resonator based technique which is accurate, simple, and space-efficient. A number of novel devices have been demonstrated using commercial CMOS-photonics fabrication foundries, with the aim of developing large-scale photonic integrated circuits using the standard process development tools. Two types of wavelength-selective, TWR-based reflective filters have been demonstrated for applications such as remote sensing and tunable lasers. Ultra-compact, high-Q microdisk resonators have been demonstrated, with radii of down to 1.5 µm, free spectral ranges (FSRs) of up to 71 nm, loaded Q's of up to 88,000, and unloaded Q's of over 100,000.Contra-DCs have been studied using coupled-mode theory. An add-drop filter designed using contra-DCs in slab-modulated rib waveguides has been proposed and demonstrated, which shows a flat-top response and a narrow bandwidth of 50--100 GHz, promising for dense-WDM applications. Also, we proposed an out-of-phase grating design to suppress the intra-waveguide reflection in contra-DCs. Using this novel anti-reflection (AR) design, we have demonstrated an add-drop filter with a single-band, flat-top response and a wide channel bandwidth of 6.5 nm, which enables athermal operation in a large temperature span of > 70 K. This AR contra-DC can be used to build an on-chip coarse-WDM system for power-efficient, ultra-high-speed optical interconnects. Furthermore, we have proposed and demonstrated an electrically tunable phase-shifted contra-DC.In order to overcome the challenges facing microring resonators, such as limited FSRs and difficulty in controlling the bus-resonator coupling, we have proposed to integrate contra-DCs with microring resonators for selective bus-resonator coupling. Using this method, we have demonstrated a single dominant resonant mode in a microring resonator that originally has a small FSR of 1.3 nm. This grating-coupled microring resonator is promising for applications that need a huge free spectral range, such as cascaded resonator sensor arrays and ultra-high-bandwidth WDM systems.

https://open.library.ubc.ca/collections/24/items/1.0073127

Modeling of the transistor vertical cavity surface emitting laser (2011)

The direct modulation of semiconductor lasers has many applications in data transmission. However, due to the frequency response it has been challenging to use directly modulated lasers for high speed digital transmission at bit-rates above 10 Gbps. With this in mind, designing a laser with a large modulation bandwidth to be used in high data-rate optical links is very important. Transistor lasers (TLs) are a potential candidate for this purpose.Based on these motivations, the main focus of this PhD research is on understanding the physics of the TL and predicting its performance. A detailed model that correctly incorporates the transistor effects on laser dynamics did not exist. The previous models do not differentiate between the bulk carriers and the quantum well (QW) carriers in the rate equations, do not include the effects of the capture and escape lifetimes in the QW, and significantly overestimate the bandwidth.To account for these phenomena, a model has been developed to study the dynamics of the TL. The model is based on the continuity equation in the separate confinement hetero-structure region of the conventional laser and the base region of the TL. It uses the quantum mechanical escape and capture of carriers in the quantum well region and the laser rate equations to model the laser operation. The model has been used to gain insight into the conventional separate confinement hetero-structure lasers, and the results of the model have been compared with the experimental results obtained for 850 nm vertical cavity surface emitting lasers(VCSELs). Analytical expressions have been derived for DC and AC parameters of the TL operating in common-base and common-emitter configurations. It has been shown that the TL operating in the common-emitter configuration has a similar modulation bandwidth as a conventional laser (~ 20 GHz). The common-base configuration, on the other hand, has a very large small-signal modulation bandwidth (> 40 GHz) due to bandwidth equalization in the TL. The large-signal performance of the TL has been studied. Finally, it has been shown that the common-emitter configuration with feedback has improved bandwidth by a factor of 1.5 in high bias currents.

https://open.library.ubc.ca/collections/24/items/1.0071881

Master's Student Supervision (2010-2017)
Highly efficient thermo-optic switches on silicon-on-insulator (2015)

We analyze and demonstrate the performance of dense dissimilar waveguide routing as a method for increasing the efficiency of thermo-optic phase shifters on a silicon-on-insulator platform. Optical, mechanical, and thermal models of the phase shifters are developed and used to propose metrics for evaluating device performance. The lack of cross-coupling between dissimilar waveguides allows highly dense waveguide routing under heating elements and a corresponding increase in efficiency. We demonstrate a device with highly dense routing of 9 waveguides under a 10 μm wide heater and, by thermally isolating the phase shifter by removal of the silicon substrate, achieve a low switching power of 95 μW, extinction ratio greater than 20 dB, and less than 0.1 dB ripple in the through spectrum. The device has a footprint of less than 800 μm x 180 μm. The increase in waveguide density achieved by using dissimilar waveguide routing is found not to negatively impact the switch response time.

https://open.library.ubc.ca/collections/24/items/1.0166684

Silicon photonic modulators and filters for optical interconnects (2015)

The goal of this work is to enhance the performance of and demonstrate new applications for silicon photonic modulators and filters. We demonstrate a variety of novel designs and applications of silicon photonic devices for integrated optical interconnects. First, we demonstrate a biasing scheme for travelling-wave Mach-Zehnder modulators in which the bias voltage is applied separately from the data signal. Using this biasing scheme, there is no low frequency cutoff and there is no power consumption in the termination resistor from the bias voltage, which results in an improved modulator having a lower overall power consumption. We experimentally show, as a proof-of-concept, successful high-speed modulation, at a data rate of 28 Gb/s, of a modulator which uses this biasing scheme. Next, we present a novel modulator design in which a microring modulator is placed into each arm of a Mach-Zehnder interferometer. This design uses the sharp phase response of a microring resonator near its resonance so that the light experiences a large phase change when a voltage is applied to the p-n junction phase shifters within the microring. We use temporal coupled mode theory to simulate the time-domain response of this modulator. We then demonstrate a novel modulator design which uses a quarter-wave phase-shifted Bragg grating. The modulator, which was fabricated using 193 nm optical lithography, has open eye diagrams at a data rate of 32 Gb/s. We also show that using a 2³¹-1 pseudorandom binary sequence pattern, the modulator has a bit error rate (BER) less than 10⁻¹² at a data rate of 20 Gb/s and has a BER less than 10⁻¹⁰ at a data rate of 25 Gb/s. Finally, we demonstrate a contra-directional grating coupler-based filter on silicon in an optical add-drop multiplexer configuration and show that it can successfully add and drop a 12.5 Gb/s signal at the same wavelength without substantial signal degradation.

https://open.library.ubc.ca/collections/24/items/1.0166635

Sub-wavelength grating ring resonators based on silicon-on-insulator technology for sensing applications (2015)

Standard silicon photonic strip waveguides offer a high intrinsic refractive index contrast; this permits strong light confinement, leading to compact bends, which in turn facilitate the fabrication of devices with a small footprint. Waveguides based on sub-wavelength gratings (SWGs) can allow the fabrication of devices with specific, engineered optical properties. The combination of SWG waveguides with optical resonators can offer the possibility of achieving ring resonators with properties different from the traditional Silicon-On-Insulator (SOI) rings. One important property that SWG rings can offer is decreased light confinement in the waveguide core; this improves the resonator’s sensitivity to changes in the cladding refractive index, making the rings ideal for refractive index sensing applications. This thesis presents the design and experimental characterization of SWG-based rings realized on SOI chips without upper cladding, permitting their use as sensors. The sensitivity achieved was 400 nm/RIU and the limit of detection was 9.9 x 10−⁴ .

https://open.library.ubc.ca/collections/24/items/1.0165822

Grating coupler design based on silicon-on-insulator (2013)

Silicon-on-insulator has become a promising platform for high-density integrated photonics circuits. The large refractive index contrast between the functional silicon layer and its cladding raises a coupling issue between an optical fibre and on-chip devices. Grating coupler provides a compact and efficient way to tackle the coupling issue between the optical fibre and silicon waveguide. In this thesis, a universal design methodology, which accommodates various etch depths, silicon thicknesses, and cladding materials has been demonstrated and verified by both FDTD simulation and measurement results. A fully etched grating coupler with a sub-wavelength grating structure has been proposed to reduce the large back reflection of existing fully etched grating couplers. Back reflection of the proposed fully etched grating coupler has been reduced from more than 20% to about 5%. The insertion loss and bandwidth of the proposed structure have also been improved. In addition, a bidirectional grating coupler for vertical coupling has been proposed to improve the insertion loss and bandwidth of the traditional grating coupler. A simulated insertion loss of -1.5dB with a 3dB bandwidth of more 100nm has been achieved with the proposed structure.

https://open.library.ubc.ca/collections/24/items/1.0073806

Photonic device design flow : from mask layout to device measurement (2012)

Mask layout design is an important part in silicon photonic device design flow; the space used and the quality of the mask directly affect the cost of fabrication and quality of the outcome. To effectively minimize time spent on drawing masks, fixing design violations, and reducing unused spacings between each structure, we use effective approaches in the mask design process to ensure the listed criteria are met. Using the PCell and the hierarchy drawing methods, GDS files that contain different device parameters can be generated efficiently. As a result, direct GDS modeling efficiency is improved. An experimental setup that is capable of obtaining high quality measurement data is critical to device measurement. The concept of an automated measurement station can effectively reduce work needed from the experimenter while providing quality results. With the implemented fiber-to-fiber and fiber array automated measurement station, multi-device measurement can be set up to run automatically in minutes whereas traditional manual measurement stations require one's presence and constant attention. In this thesis, we have illustrated several mask drawing approaches and showed the drawing steps of two masks in detail. We have described two automated experimental setups, fiber-to-fiber and fiber array, in detail and included various measurement results to show the capabilities of these two stations.

https://open.library.ubc.ca/collections/24/items/1.0073344

Silicon ring resonator add-drop multiplexers (2011)

Wavelength-division multiplexing (WDM) using silicon-on-insulator (SOI) waveguides have become an attractive area of research to decrease the footprint of optical interconnects as well as to ensure high speed data transmission. Specifically, research into using SOI ring resonator add-drop filters for WDM applications have been increasingly pursued. A ring resonator coupled on both sides by straight waveguides enables one to add (multiplex) or drop (demultiplex) wavelengths. Using series-coupled ring resonators, with each resonator having a different length, enables better spectral performance than single ring resonators. In this thesis, we have analyzed the properties of SOI strip waveguides and directional couplers. We have compared different spectral properties of single and series-coupled ring resonators and showed the advantages of using series-coupled ring resonators. SOI strip waveguide series-coupled racetrack resonators exhibiting the Vernier effect were designed by us and fabricated at a leading edge foundry. The free spectral range was 36 nm, which is comparable to the span of the optical C-band. The drop port response showed interstitial peak suppression between 9 dB and 17 dB and minimal resonance splitting.

https://open.library.ubc.ca/collections/24/items/1.0072267

Fabrication and characterization of InP semiconductor ring lasers (2010)

This thesis investigates the fabrication of 1550 nm emitting InP semiconductor racetrack resonator lasers (SRLs) via wet etching techniques. The method of choice for SRL fabrication is reported to be via dry etching. Dry etching is a complex, time consuming and expensive process which leaves relatively rougher surfaces and sidewalls compared to wet etching techniques. In this thesis, coupling, racetrack resonators, and edge emitter laser theory were studied for the SRL design. Then, a fabrication process for the SRLs was developed via wet etching techniques. The light emitting diode (LED) characteristics of the fabricated devices were observed and successfully measured. The spectrum of the device was also measured with optical spectrum analyzer (OSA) and resonances were observed.However, lasing was not observed. The cleaving process is a major limiting step in the fabrication and it is being improved. In parallel to the wet etching fabrication at UBC, dry etching (the common method for SRL fabrication) is being performed at the Centre de Recherche en Nanofabrication et Nanocaractérisation (CNR2) at the Université de Sherbrooke.

https://open.library.ubc.ca/collections/24/items/1.0071345

Publications

  • Apodized Spiral Bragg Grating Waveguides in Silicon-on-Insulator (2018)

    Ma, Minglei and Chen, Zhitian and Yun, Han and Wang, Yun and Wang, Xu and Jaeger, Nicolas AF and Chrostowski, Lukas
    IEEE Photonics Technology Letters 30 (1) 111--114

  • Automatic Configuration and Wavelength Locking of Coupled Silicon Ring Resonators (2018)

    Jayatilleka, Hasitha and Shoman, Hossam and Boeck, Robert and Jaeger, Nicolas AF and Chrostowski, Lukas and Shekhar, Sudip
    Journal of Lightwave Technology 36 (2) 210--218

  • Microwave photonic signal processing using silicon photonic Bragg gratings (Conference Presentation) (2018)

    Azana, Jose and Burla, Maurizio and Chrostowski, Lukas and Li, Ming
    Smart Photonic and Optoelectronic Integrated Circuits XX 10536 105361E

  • Narrow-Band Add-Drop Filter Based on Phase-Modulated Grating-Assisted Contra-Directional Couplers (2018)
    Huiye Qiu and Jianfei Jiang and Ping Yu and Debin Mu and Jianyi Yang and Xiaoqing Jiang and Hui Yu and Rui Cheng and Lukas Chrostowski
    Journal of Lightwave Technology 36 (17) 3760--3764
  • Automatic tuning and temperature stabilization of high-order silicon Vernier microring filters (2017)

    Jayatilleka, Hasitha and Boeck, Robert and AlTaha, Mohammed and Flueckiger, Jonas and Jaeger, Nicolas AF and Shekhar, Sudip and Chrostowski, Lukas
    Optical Fiber Communications Conference and Exhibition (OFC), 2017 1--3

  • From concept to a working silicon photonic chip (2017)

    Chrostowski, Lukas
    CLEO: Science and Innovations SF1I--1

  • High-performance silicon photonic tri-state switch based on balanced nested Mach-Zehnder interferometer (2017)

    Lu, Zeqin and Celo, Dritan and Mehrvar, Hamid and Bernier, Eric and Chrostowski, Lukas
    Scientific reports 7 (1) 12244

  • IEEE PHOTONICS SOCIETY (2017)

    BRANTLEY, CHRIS and EGGLETON, B and HAGIMOTO, K and LIM, C and NOUCHI, P and ESSIAMBRE, RJ and LIBROIRON-LADOUCER, O and POOLE, S and RUSCH, L and CINNOTTI, G and others

  • Broadband 2$\times$ 2 adiabatic 3 dB coupler using silicon-on-insulator sub-wavelength grating waveguides (2016)

    Yun, Han and Wang, Yun and Zhang, Fan and Lu, Zeqin and Lin, Stephen and Chrostowski, Lukas and Jaeger, Nicolas AF
    Optics letters 41 (13) 3041--3044

  • Ultra-Compact Sub-Wavelength Grating Polarization Splitter-Rotator for Silicon-on-Insulator Platform (2016)

    Wang, Yun and Ma, Minglei and Yun, Han and Lu, Zeqin and Wang, Xu and Jaeger, Nicolas AF and Chrostowski, Lukas
    IEEE Photonics Journal 8 (6) 1--9

  • Process calibration method for designing silicon-on-insulator contra-directional grating couplers (2015)

    Boeck, Robert and Caverley, Michael and Chrostowski, Lukas and Jaeger, Nicolas AF
    Optics express 23 (8) 10573--10588

  • Coupler-apodized Bragg-grating add--drop filter (2013)

    Shi, Wei and Yun, Han and Lin, Charlie and Flueckiger, Jonas and Jaeger, Nicolas AF and Chrostowski, Lukas
    Optics letters 38 (16) 3068--3070

  • Fully etched grating coupler with low back reflection (2013)

    Wang, Yun and Shi, Wei and Wang, Xu and Flueckiger, Jonas and Yun, Han and Jaeger, Nicolas AF and Chrostowski, Lukas
    Photonics North 2013 8915 89150U

  • Integrated Bragg gratings in spiral waveguides (2013)

    Wang, Xu and Yun, Han and Chrostowski, Lukas
    Lasers and Electro-Optics (CLEO), 2013 Conference on 1--2

  • Thermally tunable quadruple Vernier racetrack resonators (2013)

    Boeck, Robert and Chrostowski, Lukas and Jaeger, Nicolas AF
    Optics letters 38 (14) 2440--2442

  • Ultra-compact, flat-top demultiplexer using anti-reflection contra-directional couplers for CWDM networks on silicon (2013)

    Shi, Wei and Yun, Han and Lin, Charlie and Greenberg, Mark and Wang, Xu and Wang, Yun and Fard, Sahba Talebi and Flueckiger, Jonas and Jaeger, Nicolas AF and Chrostowski, Lukas
    Optics express 21 (6) 6733--6738

  • Ring resonator wavelength division multiplexing interleaver (2011)

    Gad, Michael and Ackert, Jason and Yevick, David and Chrostowski, Lukas and Jessop, Paul E
    Journal of Lightwave Technology 29 (14) 2102--2108

  • Design and characterization of microring reflectors with a waveguide crossing (2010)

    Shi, Wei and Vafaei, Raha and Torres, Miguel Angel Guillen and Jaeger, Nicolas AF and Chrostowski, Lukas
    Optics letters 35 (17) 2901--2903

  • Design of a 1550 nm SiGe (2010)

    TASMIN, Tania and ROUGER, Nicolas and GUANGRUI, XIA and CHROSTOWSKI, Lukas and JAEGER, Nicolas AF
    Proceedings of SPIE, the International Society for Optical Engineering

  • Interference effects on the frequency response of injection-locked VCSELs (2010)

    Wang, Xu and Faraji, Behnam and Hofmann, Werner and Amann, Markus C and Chrostowski, Lukas
    Semiconductor Laser Conference (ISLC), 2010 22nd IEEE International 85--86

  • Modelling the effect of the feedback on the small signal modulation of the transistor laser (2010)

    Faraji, Behnam and Jaeger, Nicolas AF and Chrostowski, Lukas
    Photonics Society, 2010 23rd Annual Meeting of the IEEE 525--526

  • Optical gratings: Nano-engineered lenses (2010)

    Chrostowski, Lukas
    Nature Photonics 4 (7) 413

  • Optical oxygen sensors for applications in microfluidic cell culture (2010)

    Grist, Samantha M and Chrostowski, Lukas and Cheung, Karen C
    Sensors 10 (10) 9286--9316

  • Self-consistent modeling of a transistor vertical-cavity surface-emitting laser (2010)

    Shi, Wei and Faraji, Behnam and Greenberg, Mark and Berggren, Jesper and Xiang, Yu and Hammar, Mattias and Chrostowski, Lukas
    Numerical Simulation of Optoelectronic Devices (NUSOD), 2010 10th International Conference on 45--46

  • Series-coupled silicon racetrack resonators and the Vernier effect: theory and measurement (2010)

    Boeck, Robi and Jaeger, Nicolas AF and Rouger, Nicolas and Chrostowski, Lukas
    Optics express 18 (24) 25151--25157

  • Silicon Nanophotonics Fabrication: an Innovative Graduate Course (2010)

    Chrostowski, Lukas and Rouger, Nicolas and Deptuck, Dan and Jaeger, Nicolas AF
    Telecommunications (ICT), 2010 IEEE 17th International Conference on 544--551

  • Silicon-on-insulator Bragg gratings fabricated by deep UV lithography (2010)

    Wang, Xu and Shi, Wei and Vafaei, Raha and Jaeger, Nicolas AF and Chrostowski, Lukas
    Communications and Photonics Conference and Exhibition (ACP), 2010 Asia 501--502

  • Temperature effects on silicon-on-insulator (SOI) racetrack resonators: A coupled analytic and 2-D finite difference approach (2010)

    Rouger, Nicolas and Chrostowski, Lukas and Vafaei, Raha
    Journal of Lightwave Technology 28 (9) 1380--1391

  • Analytical modeling of the transistor laser (2009)

    Faraji, Behnam and Shi, Wei and Pulfrey, David L and Chrostowski, Lukas
    IEEE Journal of Selected Topics in Quantum Electronics 15 (3) 594--603

  • Numerical investigation of the effect of base doping density in transistor VCSELs (2009)

    Shi, Wei and Faraji, Behnam and Chrostowski, Lukas
    Asia Communications and Photonics Conference and Exhibition TuB3

  • Simulation of coupling between parallel SOI nanowaveguides and its dependence on temperature (2009)

    Rouger, Nicolas and Chrostowski, Lukas
    Optical MEMS and Nanophotonics, 2009 IEEE/LEOS International Conference on 103--104

  • Common-emitter and common-base small-signal operation of the transistor laser (2008)

    Faraji, B and Shi, W and Pulfrey, DL and Chrostowski, L
    Applied Physics Letters 93 (14) 143503

  • Numerical study of the optical saturation and voltage control of a transistor vertical-cavity surface-emitting laser (2008)

    Shi, Wei and Chrostowski, Lukas and Faraji, Behnam
    IEEE Photonics Technology Letters 20 (24) 2141--2143

  • 40 GHz Bandwidth and 64 GHz Resonance Frequency in Injection-Locked 1.55 $μ$m VCSELs (2007)

    Chrostowski, Lukas and Faraji, Behnam and Hofmann, Werner and Amann, Markus-Christian and Wieczorek, Sebastian and Chow, Weng W
    IEEE Journal of Selected Topics in Quantum Electronics 13 (5) 1200--1208

  • Distributed subwavelength grating demultiplexer in SOI (2007)

    Bisaillon, Eric and Tan, Dawn TH and Nadeau, Marie-Claude and Chrostowski, Lukas and Kirk, Andrew
    Integrated Optics: Devices, Materials, and Technologies XI 6475 64750C

  • Measuring blood glucose using vertical cavity semiconductor lasers (vcsels) (2007)

    Fard, Sahba Talebi and Chrostowski, Lukas and Kwok, Ezra
    CMBES Proceedings 30 (1)

  • Peak blood glucose prediction algorithm following a meal intake (2007)

    Islam, Shafiqul and Leech, James and Lin, Charles CY and Chrostowski, Lukas
    Electrical and Computer Engineering, 2007. CCECE 2007. Canadian Conference on 579--582

  • 50-GHz optically injection-locked 1.55-/spl mu/m VCSELs (2006)

    Chrostowski, Lukas and Zhao, X and Chang-Hasnain, CJ and Shau, R and Ortsiefer, M and Amann, M-C
    IEEE photonics technology letters 18 (2) 367--369

  • Distributed-grating wavelength demultiplexer in SOI (2006)

    Bisaillon, E and Tan, DTH and Nadeau, M-C and Chrostowski, L and Kirk, AG
    Lasers and Electro-Optics Society, 2006. LEOS 2006. 19th Annual Meeting of the IEEE 462--463

  • High extinction ratio of injection-locked 1.55-/spl mu/m VCSELs (2006)

    Zhao, Xiaoxue and Chrostowski, Lukas and Chang-Hasnain, Connie J
    IEEE photonics technology letters 18 (1) 166--168

  • Modified optical heterodyne down-conversion system for measuring frequency responses of wideband wavelength-sensitive electrooptical devices (2006)

    Lam, Alfred KM and Chrostowski, Lukas and Faraji, Behnam and Kisch, Ryan and Jaeger, Nicolas AF
    IEEE photonics technology letters 18 (20) 2183--2185

  • VCSEL tolerance to optical feedback (2005)

    Subrahmanyam, P Bala and Zhou, Y and Chrostowski, L and Chang-Hasnain, CJ
    Electronics Letters 41 (21) 1178--1179

  • 39 GHz intrinsic bandwidth of a 1.55 um injection-locked VCSEL (2004)

    Chrostowski, Lukas and Moewe, Michael and Zhao, Wendy and Chang, Chih-Hao and Shau, Robert and Ortsiefer, Markus and Amann, Markus-Christian and Chang-Hasnain, Connie
    Conference on Lasers and Electro-Optics CTuAA7

  • 39 GHz intrinsic bandwidth of a 1.55/spl mu/m injection-locked VCSEL (2004)

    Chrostowski, L and Moewe, M and Zhao, W and Chang, Chih-Hao and Chang-Hasnian, C and Shau, R and Ortsiefer, M and Amann, M-C
    Lasers and Electro-Optics, 2004.(CLEO). Conference on 1 2--pp

  • A novel, low V/sub/spl pi//L EIT based optical modulators (2004)

    Ku, PC and Chrostowski, L and Chang-Hasnain, CJ
    Microwave Photonics, 2004. MWP'04. 2004 IEEE International Topical Meeting on 97--100

  • Dynamic range enhancement in 1.55/spl mu/m VCSELs using injection-locking (2004)

    Zhao, Xiaoxue and Chrostowski, Lukas and Chang-Hasnain, Connie J
    Microwave Photonics, 2004. MWP'04. 2004 IEEE International Topical Meeting on 111--114

  • Extinction ratio of injection-locked VCSELs (2004)

    Zhao, Xiaoxue and Chrostowski, Lukas and Chang-Hasnain, Connie
    Lasers and Electro-Optics Society, 2004. LEOS 2004. The 17th Annual Meeting of the IEEE 1 244--245

  • Injection-locked 1.55-/spl mu/m tunable VCSEL for uncooled WDM transmitter applications (2004)

    Chrostowski, Lukas and Chang, Chih-Hao and Chang-Hasnain, Connie J
    IEEE Photonics Technology Letters 16 (3) 888--890

  • Optical injection locking of vertical cavity surface emitting lasers (2004)

    Chrostowski, Lukas

  • VCSEL tolerance to optical feedback for inter-chip optical interconnects (2004)

    Chrostowski, L and Subrahmanyam, P Bala and Zhou, Y and Chang-Hasnain, CJ
    Semiconductor Laser Conference, 2004. Conference Digest. 2004 IEEE 19th International 113--114

  • Very high resonance frequency (> 40 GHz) optical injection-locked 1.55/spl mu/m VCSELs (2004)

    Chrostowski, L and Zhao, X and Chang-Hasnain, CJ and Shau, R and Ortsiefer, M and Amann, M-C
    Microwave Photonics, 2004. MWP'04. 2004 IEEE International Topical Meeting on 255--258

  • Enhanced VCSEL performance by optical injection locking for analog and digital applications (2003)

    Chang, C-H and Chrostowski, Lukas and Chang-Hasnain, Connie
    Lasers and Electro-Optics Society, 2003. LEOS 2003. The 16th Annual Meeting of the IEEE 2 704--705

  • Enhancement of dynamic range in 1.55-$μ$m VCSELs using injection locking (2003)

    Chrostowski, Lukas and Chang, Chih-Hao and Chang-Hasnain, Connie J
    IEEE Photonics Technology Letters 15 (4) 498--500

  • Frequency response enhancement of injection-locked lasers (2003)

    Chang, C-H and Chrostowski, Lukas and Chang-Hasnain, Connie
    Lasers and Electro-Optics, 2003. CLEO'03. Conference on 2--pp

  • Injection locking of VCSELs (2003)

    Chang, Chih-Hao and Chrostowski, Lukas and Chang-Hasnain, Connie J
    IEEE Journal of Selected Topics in Quantum Electronics 9 (5) 1386--1393

  • Reduction of relative intensity noise and improvement of spur-free dynamic range of an injection locked VCSEL (2003)

    Chrostowski, Lukas and Chang, C-H and Chang-Hasnain, C
    Lasers and Electro-Optics Society, 2003. LEOS 2003. The 16th Annual Meeting of the IEEE 2 706--707

  • Uncooled injection-locked 1.55 um tunable VCSEL as DWDM transmitter (2003)

    Chrostowski, Lukas and Chang, Chih-Hao and Chang-Hasnain, Connie J
    Optical Fiber Communication Conference FO2

  • Analog Modulation Dynamic Range Enhancement Using Injection-Locked 1.55 mm VCSELs (2002)

    Chang, CH and Chrostowski, L and Chang-Hasnain, CJ
    International Conference on Semiconductor Lasers, Germany

  • Study of long-wavelength VCSEL-VCSEL injection locking for 2.5-Gb/s transmission (2002)

    Chang, Chih-Hao and Chrostowski, Lukas and Chang-Hasnain, Connie J and Chow, Weng W
    IEEE Photonics Technology Letters 14 (11) 1635--1637

  • Parasitics and design considerations on oxide-implant VCSELs (2001)

    Chang, Chih-Hao and Chrostowski, Lukas and Chang-Hasnain, Constance J
    IEEE Photonics Technology Letters 13 (12) 1274--1276

  • Study of long-wavelength directly modulated VCSEL transmission using SOA amplifiers (2001)

    Chrostowski, L and Chang, CH and Stone, RJ and Chang-Hasnain, C
    Optical Communication, 2001. ECOC'01. 27th European Conference on 3 432--433

  • Transmission improvement of VCSEL at 2.5 Gb/s under injection locking by another VCSEL (2001)

    Chang, CH and Chrostowski, L and Chang-Hasnain, CJ
    Lasers and Electro-Optics Society, 2001. LEOS 2001. The 14th Annual Meeting of the IEEE 2 728--729

 
 

If this is your researcher profile you can log in to the Faculty & Staff portal to update your details and provide recruitment preferences.