Development of high speed vertical cavity surface-emitting semiconductor diode laser and transistor laser
High speed semiconductor lasers are used in optical transceivers for short-reach data links. With fast-growing data capacity and traffic in the data centers around the globe, faster optical transceivers are demanded. A microcavity vertical cavity surface-emitting laser (VCSEL) is able to show a high modulation bandwidth as well as single-mode operation; however, because of the small oxide aperture (< 3 µm), a microcavity VCSEL shows high resistance and low optical power. An 850 nm oxide-confined VCSEL with an aperture ~4 µm is able to show error-free transmission at 40 Gb/s. With an advanced DBR design for parasitic reduction as well as better thermal conduction and a short 0.5-λ cavity with five quantum wells, an 850 nm VCSEL is able to demonstrate 57 Gb/s error-free transmission at 25 °C and 50 Gb/s error-free transmission at 85 °C. The dynamic carrier profile in the base of a transistor laser makes it possible to have a shorter carrier lifetime than in a diode laser. The first oxide-confined vertical cavity transistor laser (VCTL) is realized with a trench oxidation process and a lateral-feeding base metal design. To further reduce the excessive emitter series resistance, a VCTL with AlGaAs and dielectric distributed Bragg reflector (DBR) is fabricated. Because of the mismatch between the cavity design and the quantum well emission, the VCTL is only able to show stimulated emission at low temperatures.
Vertical Cavity Surface-Emitting Laser, Vertical Cavity Transistor Laser
University of Illinois - Urbana-Champaign
Networked Digital Library of Theses and Dissertations
University of Illinois at Urbana-Champaign