Optical Phased Laser Arrays and Their Functionality

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

Title: Coupling Multiple Semiconductor Lasers in a Single Chip for Applications of Fast Optical Data Transmission or High Power Operation Semiconductor lasers have an increasingly significant impact on many aspects of our daily lives, as well as the economy and security of our nation. The internet relies upon tiny lasers to transmit information originating from our smart phones and computers through optical fiber to destinations around the world, while the low cost manufacture automobiles, planes, and consumer goods require lasers for precision cutting and welding. To continue the expansion and improve the performance of the internet, or to further reduce manufacturing costs, improved performance of the properties of semiconductor lasers are necessary. Conventional approaches for further improvements are not obvious, whereby for both high speed data transmission as well as high power laser light output the laser manufacturing industry are near the limits of performance, in technology areas that are accustomed to an order of magnitude increase every few years or less. Therefore new ideas and paradigms are needed to break through these performance barriers. The research of this project seeks to develop new semiconductor laser chips that will address faster optical transmission of data as well as increased laser output power. The ability to distribute greater amounts of digital data over optical fiber with orders of magnitude less electricity and at faster rates, would be a key enabler for data centers, which has been identified in a recent National Academy of Engineering report as a critical U.S. challenge. High power lasers will also lead to more reliable manufacturing processes and lower cost production, or more compact laser sources for display applications. Finally, the development of high brightness lasers could also enable a new generation of directed energy weapons for enhanced U.S. security. This research program incorporates design, simulation, fabrication, and characterization of semiconductor lasers to challenge and educate a diverse group of undergraduate and graduate students in electrical engineering in both classroom and laboratory experiences. The approach of this research is to develop multiple lasers within a single semiconductor chip to act together in a coherently coupled manner. Specifically, the light wavelength and phase of each of the lasers in the array will be controlled in such a manner that all of the laser beams are combined together coherently. The coherent combination of the lasers does not simply result in the addition of the beams, but in fact the overall output light intensity increases as the square of the number of lasers in the array. Moreover, the control of the phase of each of the lasers in an array with all of the beams coherently combined can produce a significant increase of the modulation rate (the rate of turning the laser light brighter and dimmer) for digital transmission applications. The key aspect to control the light wavelength and phase of each laser element of the array is to independently electrically contact each laser diode. The intellectual merit of this research originates from the control and manipulation of multiple quantum mechanical optical oscillators. The fabrication approaches that are used in this research project are the same as those presently employed to manufacture individual semiconductor lasers, and thus can be transferred to the laser manufacturing industry in the United States. Furthermore and perhaps most importantly, the students involved in this research will be prepared for future scientific and engineering careers in the U. S. photonics industry.