Jun 6 (Fri) @ 9:30am: ”Quantum Dot Frequency-Modulated Combs for Data Transmission,” Mario Dumont, ECE PhD Defense

Zoom Meeting: https://ucsb.zoom.us/j/81088853494

Abstract

Data centers, especially those focused on AI computing, have driven the need for intimate copackaging optics and electronics. This integration imposes strict constraints on the size and power consumption of the next generation optical-transceivers. Current approaches employ multiple single-frequency lasers, which offer no avenue for further size reduction. This limitation necessitates the development of next-generation photonics that implement multi-wavelength optical sources for dense wavelength-division-multiplexing (DWDM). Semiconductor mode locked lasers (MLLs) output a cascade of optical tones, or wavelengths, with a fixed channel spacing known as an optical frequency comb. This makes MLLs a leading technology in multi-wavelength optical sources offering a compact, energy and space efficient design with turnkey operation.

Quantum dot (QD) Lasers have found a broad range of applications owing to their unique gain properties, with an atom-like density of states. This has given them the ability to reach the highest CW lasing temperature recorded, allows for reflection insensitive operation enabling deployment without isolators, and producing defect tolerant lasers, which provides a pathway to III-V lasers directly grown inside silicon photonic-integrated-circuits. It has also enabled a new generation of MLLs, which have applications in the formation of optical frequency combs for DWDM light sources. 

QD-MLLs produce flat-topped, high-power combs with low power consumption. The dynamics of these combs were studied, revealing that they are governed by frequency-modulated comb formation, which generates a quasi-continuous-wave output and equally distributed power in the spectral domain, making it ideal for data transmission. Furthermore, the energy efficiency of comb generation has been significantly improved to match that of commercial DFB lasers, thanks to advancements in laser growth, fabrication, and design.  As a result, a single QD-MLL has been able to achieve data transmission rates of 12 terabits per second (Tb/s).

Bio

Mario Dumont received his B.S. in physics from the University of Colorado, Boulder in 2015, and M.S. degree from University of California, Santa Barbara in 2018. He is currently pursuing the Ph.D. degree at the Department of Electrical and Computer Engineering, University of California, Santa Barbara. His current research interests are the growth, fabrication, and characterization of Quantum Dot Mode locked lasers, particularly for uses in data transmission.

Hosted by: Mario Dumont

Submitted by: Mario Dumont <mariodumont@ucsb.edu>