Semiconductor Diode Laser History and the Birth of Surface Emitting Structures By Emeritus Prof. Peter Zory, University of Florida
Abstract: Laser beams generated in the p-n junction regions of forward biased GaAs diode chips were first observed in September 1962. Laser action was achieved by cooling the chips to liquid nitrogen temperature (77K) and pumping them with short, high current pulses. By 1967, room temperature (300K) pulsed devices were commercially available and being used in a number of defense applications. At the time, it was realized that these photonics sources could be the drivers for a host of new applications if a number of improvements in device performance could be achieved. This realization prompted the creation of the first International Semiconductor Laser Conference (ISLC-1) in 1967 where it was expected that idea-exchange between participants would speed the achievement of the required performance improvements. During the intervening years between 1967 and 1990 when 12 ISLCs were held, the diode laser chip evolved from its simple two-layer ’62 form to a variety of forms including that of the first mass-produced laser, the compact disc (CD) diode laser. As the CD laser was reaching maturity in the late 70s, work on another type of laser structure was started at Tokyo Institute of Technology where the mirrors required for laser action were located on the opposing surfaces of the laser chip rather than on opposing edge facets. While it took several years for Professor Iga and his research group to achieve pulsed operation at 300K using a vertical cavity surface emitting laser (VCSEL) strucuture, devices operating continuously at 300K with sub-milliamp threshold currents were being demonstrated worldwide just a few years later. In this talk, highlights of the twelve ISLCs held between 1967 and 1990 will be presented showing how diode laser chips evolved in that time period. Emphasis in the presentation will be placed on internal structure changes that led to a reduction in threshold current densities of about three orders of magnitude and early realizations of surface emitting designs.
Surface-Emitting and Edge-Emitting Semiconductor Lasers: Fabrication and Integration By Prof. Gary A. Evans, Southern Methodist University
Abstract: Vertical cavity surface-emitting lasers (VCSELs) emit light from a relatively large aperture located on the surface of the laser die and have a short (< 5 µm), fixed cavity length defined by a complex epitaxial structure. Edge-emitting (horizontal cavity) semiconductor lasers emit from a relatively small aperture located on the edge of the laser die and can have very long (~ 500 µm) cavity lengths. As a result, the spectral properties, radiation patterns and output powers are quite different. Unlike edge-emitting laser, surface emission allows testing of VCSELs at the wafer level. This talk will contrast the fabrication, testing and packaging processes of these two laser architectures. In addition, current efforts towards integrating photonic sources with additional optical and electronic components will be discussed.
From Micro-optic Technologies and Nano-photonics Applications: Progress and Prospects By Prof. C. Chang-Hasnain, University of California-Berkeley
The invention and development of vertical-cavity surface-emitting laser (VCSEL) marked the beginning of micro-photonics. With a factor of ~100 reduction in active region volume, VCSEL significantly reduced energy consumption which made possible for high port count, high aggregate bandwidth optical interconnects. With the advances in nano-scale fabrication technologies, there is great interest to “tailor” materials’ physical properties when their sizes are made small enough for manipulation of absorption, emission, transmission, refraction, transport, etc. in innovative ways that could have profound implications for many applications. In this talk, I will discuss some of the recent developments.