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Research

Coherent Fiber Optic Transmission Systems

This research is organized in three large projects: spatial division multiplexing (SDM), energy-efficient transmission, and novel transmission schemes. The SDM project aims at finding efficient transmission schemes over parallel optical channels. The energy efficiency project involves close collaborations with the E2 and CSE departments for a holistic view of the energy consumption of optical links. The novel transmission scheme project includes demonstrations of frequency comb-based transmission with record spectral efficiency of 11.5 bit/s/Hz.

 

Parametric Processing and Amplification

This research utilizes the unique features of phase-sensitive optical amplifiers - producing nearly no excess noise and the ability to mitigate transmission fiber nonlinearities. Significant reach extension in long-haul fiber transmission was demonstrated using QPSK and QAM signals. Additional benefits of distributed Raman amplification, few-mode fibers, and processing in highly nonlinear integrated waveguides are investigated. Very high sensitivity receivers for free-space optical communication were demonstrated.

 

Ultrafast Photonics

This research focuses on laser frequency comb technology for applications in fiber-optic communication systems and ultrafast metrology. Record transmission reach using an integrated frequency comb generator as the multi-wavelength light source was recently demonstrated. The technology for hybrid integration with silicon photonics integrated circuits is also being developed.

 

VCSELs and Optical Interconnects

Here, vertical-cavity surface-emitting lasers (VCSELs) and associated technologies for applications in datacom and life science are being developed. VCSEL-based transmitters with record speed and efficiency were demonstrated. Dense arrays of high-speed VCSELs enabled record capacity multicore fiber interconnects. Single-channel speed above 100 Gbps was demonstrated by using multilevel modulation. Heterogeneous integration of hybrid vertical-cavity lasers on silicon demonstrated the potential of such lasers as efficient light sources for silicon photonic integrated circuits.

 

Wide Bandgap Optoelectronics

This research focuses on light-emitters from wide-bandgap materials for ultraviolet and visible wavelengths. Devices such as resonant-cavity light-emitting diodes and microcavity lasers, from both planar and nanostructured materials are investigated for applications in solid-state lighting, visible light communication and medical diagnosis. Novel fabrication techniques for GaN-based VCSELs, thin-film LEDs, and membrane based emitters are being developed.

 

Epitaxy of Novel Bismuth-Containing Materials

The research focuses on epitaxial growth of high quality dilute-bismides for lasers and bismuth-telluride topological insulator (TI) for spintronic device applications. The first long-wavelength GaAsBi quantum well lasers operating at room temperature were demonstrated, as well as spin injection from GaAs into 3D Bi2Te3 TIs.​ 

 

Published: Thu 06 Sep 2012. Modified: Thu 05 Apr 2018