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Photonics and Optics

Our group is working in the areas of optical communications, high frequency optical modulators, fiber communication, semiconductor lasers, vertical cavity lasers, and bio-photonics.

Faculty involved:

Research Topics include:

Bio-photonics

Biophotonics is the use of light (photons) to study biological material. Light interacts with living organisms and organic material, to provide useful information, such as early cancer detection, glucose monitoring for diabetes patients. Techniques include microscopy, imaging, and absorption spectroscopy.

High-speed modulators

We are designing and fabricating ultrahigh-speed modulators for the telecommunications industry. This research has led to a start-up company, http://www.versawave.com. Current research is aimed at improving and characterizing the frequency response of quantum-well GaAs polarization mode converter modulators.

Nanowires

Optical Communications

As the demand for communications continuously increases, optical communications networks will become even more ubiquitous than they are today. In order to keep pace with the demand, we will require integrated photonic and electronic devices and systems that are low cost, small sized and support very high data rates. We are developing the next generation devices that will increase the capacity of optical communications networks, including optical modulators and semiconductor lasers.

Optical MEMS

We are working on miniaturized optical components such as stearable micromirrors and lenses, fabricated in MEMS technology. These components are used for measurement applications as well as for displays, non-homogeneous illumination and adaptive optics.

Optical sensors

Vertical Cavity Lasers (VCSELs)

Vertical Cavity Surface Emitting Lasers (VCSELs) are very small and low power semiconductor lasers, useful for optical communications and biophotonics. We are developing high-speed VCSELs for 40+ GHz operation, and are designing VCSELs based on sub-wavelength grating and photonic crystals. We are using VCSELs for spectroscopy applications (e.g. glucose), and optical communications (e.g. radio over fiber, digital transmission).

Research Projects include:

This project proposes to fabricate Optical Micro-Electro-Mechanical Systems (O-MEMS)for optical acceleration measurements. These would allow for more sensitive, accurate, and reliable measurements, exploiting advantages such as the linear relation between the velocity and the Doppler frequency shift, and the high, wavelength-dependent resolution levels achievable.
We are developing FPGA-base high-speed control for arrays of electrostatically driven micromirrors.
FPGA
The goal of this proposed project is to develop a revolutionary semiconductor laser transmitter technology, based on the homogeneous integration of photonics and electronics. The new device, a TX-VCSEL, is the integration of a high frequency Heterojunction Bipolar Transistor (HBT) with a Vertical Cavity Surface Emitting Laser (VCSEL).
Mirco-ring lasers (MRLs) are compact semiconductor lasers, where the output light is coupled directly into a planar waveguide, making them suitable for monolithic integration with other optical components, and promising for optical communications and optical interconnects. We are integrating a heterojunction bipolar transistor (HBT) structure into the MRL, and designing for very high frequency modulation modulation (>40 GHz).
Plants capture photons very efficiently. Can we learn from them in making photovoltaic devices? We are investigating the use of photosynthetic protein complexes in solar cells, with the aim of creating very low cost solar cells.
Silicon waveguides using SOI substrate allow for the fabrication of extremely compact photonic circuits based on standard CMOS processing. The goal of this project is to simulate, design and characterize several highly attractive optical functions and sub-systems in silicon photonics.
We are fabricating high-speed VCSELs in GaAs for 850 nm emission. Multi-wavelength VCSEL arrays are being developed. The fabrication is carried out in the AMPEL Nanofabrication Laboratory. We are currently fabricating devices based on sub-wavelength gratings (see e.g. Optics Express 2006 article).
Optical injection locking uses a second (master) laser to inject photons at a similar wavelength into the transmitter laser (termed follower or slave). Under certain conditions, the follower laser is locked in phase to the master, and the laser dynamics fundamentally change and can result in far better device performance.
This research project aims to develop an implantable, biocompatible, optical glucose monitor, which would have a tremendous health-care benefit, providing an improved glucose-monitoring tool for diabetics. It is based on semiconductor laser sources (VCSELs) at the ideal wavelength for optical glucose sensing.
The objective of this project is to design and construct a confocal imaging engine using MOEMS technology and to couple this with Raman Spectroscopy system in order to form a handheld device with dual complementary capabilities: cellular-level resolved confocal skin imaging combined with accurate and precise Raman spectroscopy of specific subsurface skin microstructures in vivo.
This project aims to design a photoacoustic imaging system for prostate cancer study. Images will be acquired by using a laser to excite acoustic waves from tissues and an ultrasound transducer array to detect the acoustic waves. The photoacoustic imaging will be combined with ultrasound imaging to study prostate cancer.
This project aims to develop micro-endoscopes for in vivo intra-luminal tissue imaging. The design will use state-of-the-art techniques such as photonic crystal fibers, micro-optics, and MEMS scanners. The micro-endoscopes will enable high resolution, multimodality imaging of subsurface structures and compositions of internal organs.
This project aims to develop a multimodality optical imaging system by integrating multiphoton microscopy (MPM) with optical coherence tomography (OCT). MPM is sensitive to cells and extracellular matrix, and OCT to structural interfaces and tissue layers. The system will acquire structural and functional imaging of tissues simultaneously.
Optical coherence tomography (OCT) utilizes techniques such as interferometry and coherence gating to obtain high-resolution tissue images. We develop OCT systems for biomedical and industrial applications.
Through collaboration with the BC Cancer Research Center, our optical imaging systems and endomicroscopes will be applied to study lung and skin cancers. In vivo optical imaging will help doctors to detect cancer in its early stage.
Multiphoton microscopy (MPM) is a non-invasive, high-resolution imaging method for looking at thick biological tissues. We use a femtosecond laser to develop MPM systems which can acquire two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) simultaneously. The MPM system is used to image cells and extracellular matrix in turbid tissues.
A significant challenge in research on nanostructures is the lack of sufficient control over the fabrication processes. Therefore, an important aspect of our research is the study of nanostructure fabrication processes with the goal of achieving higher levels of control and reproducibility.
When electrons are confined in one or more dimensions, their wave nature and quantum mechanical effects become very apparent. Devices such as quantum wires and quantum dots operate based on this principle. We work on fabricating such devices by exploiting the inherent properties of nanotubes and nanowires.
In nanoscale optical devices, both the particle and the wave nature of light can play important roles. This creates new opportunities for engineering the optoelectronic properties, for instance the amount of light absorption in a device.
We use techniques ranging from classical, continuum modeling, to molecular dynamics, to quantum mechanical simulations using the density functional theory and first-principles techniques such as the Hartree-Fock method. We investigate the mechanical properties, electronic structure, transport characteristics and optical properties of nanodevices.
The objective of this project is to build an adaptive micro-optical systems using a 2D micromirror array adaptively controlled through digital signal processing algorithms implemented in reconfigurable hardware (FPGA)
We are designing a Vertical-Cavity Surface-Emitting Laser (VCSEL) structure, containing a Sub-Wavelength Grating (SWG) and a Photonic Crystal (Phc) slab, either of which might replace one of the Distributed Bragg Reflectors (DBRs), using Finite-Difference Time-Domain (FDTD) and a transfer matrix method.
This project aims at developing arrays of micromirrors with high resonance frequencies and high tilt angles in all directions. The mirrors are actuated through electrostatic forces to reach continuous tilt angles. The mirrors are fabricated using multi user MEMS processes.
A magnetically actuated MEMS scanner with a microfabricated ferromagnetic nickel platform and thermosetting polydimethylsiloxane (PDMS) microlens is demonstrated. The device is driven by an external AC magnetic field, eliminating chip circuitry and thermal deformation from joule heating. The resonant frequency of 215.2 Hz and scanning angle of 23 of the scanner have been demonstrated.
By embedding low dimensional (0D, 1D, 2D) materials such as nanowires, nanotubes and quantum dots in polymers, we want improve the conversion efficiency and extend the use of solar energy, as a viable clean energy solution. Significant improvements in photocurrent and photoabsorption of polymers doped with carbon nanotubes are promising for nanocomposite solar cells.