Development of transistor lasers for high-speed short-haul communication links

Bambery, Rohan

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https://hdl.handle.net/2142/73050 Copy

Description

Title

Development of transistor lasers for high-speed short-haul communication links

Author(s)

Bambery, Rohan

Issue Date

2015-01-21

Director of Research (if dissertation) or Advisor (if thesis)

Feng, Milton

Doctoral Committee Chair(s)

Feng, Milton

Committee Member(s)

• Dallesasse, John
• Schutt-Ainé, José E.
• Goddard, Lynford L.

Department of Study

Electrical & Computer Eng

Discipline

Electrical & Computer Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Transistor Lasers
• Process Development
• Characterization
• High Speed
• Data Transmission
• Error Free
• 22 Gb/s
• Recombination Lifetime

Abstract

As data-center-based services such as cloud computing, HD and 4K video streaming, and social media become more ubiquitous, the demand for higher-performance data centers grows concurrently. Modern data centers require gargantuan amounts of power for operations and cooling and are eschewing traditional copper-based interconnects for 850 nm Vertical-Cavity Surface-Emitting Laser (VCSEL)-based interconnects. The future of ultra high-speed interconnects lies in the development and optimization of semiconductor laser-based transmitters. The subject of this dissertation encompasses the design, fabrication, and characterization of high-speed Transistor Lasers (TL) for the development of next-generation optical transmitters and opto-electronic integrated circuits. Fabrication techniques are analyzed, redesigned and improved to reliably yield devices that are able to transmit data at 20 Gb/s at room temperature. Device physics are studied with a view toward obtaining a more comprehensive understanding of the myriad processes affecting device performance. In Chapter 1 of this thesis an overview of optical communications is presented and key differences between telecom and datacom transceivers are identified. The invention of the transistor laser, its underlying physics and potential are discussed. Chapter 2 focuses on failure analysis of the second-generation process and its redevelopment into a robust, well-documented process capable of high yields. Physical analysis of the device is introduced in Chapter 3, focusing on the ability to use the TL structure to tune the spontaneous recombination lifetime in the base region. The effect of photon assisted tunneling on the operation of the device is discussed and potential uses outlined. Chapter 4 details the high-speed performance achieved with the devices. The TL shows the capability of current and voltage modulation and also demonstrated 28 dB reduction in relative intensity noise compared to a Fabry Perot diode laser. Chapter 5 discusses Bit Error Ratio (BER) characterization in detail. The cause of reduced signal-to-noise ratio is identified and optimum device selection is detailed. The measurement setup is optimized from the ground up in great detail and error-free transmission at 22 Gb/s is demonstrated. Chapter 6 lays out challenges ahead as well as those being currently tackled. Sealed ampoule Zn diffusion is integrated into the TL process and demonstrates a reduction in base series resistance. Chapter 7 presents a summary of the research described in this dissertation.

Graduation Semester

2014-12

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http://hdl.handle.net/2142/73050

Copyright and License Information

Copyright 2014 Rohan K. Bambery

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