Spectral control of diode lasers using external waveguide circuits

We investigated spectral control of diode lasers using external waveguide circuits. The purpose of this work is to investigate such external control for providing a new class of diode lasers with technologically interesting properties, such as a narrow spectral bandwidth and spectrally tunable output in a hybrid integrated format. In more detail, they consist of an integrated optics waveguide circuit with micro-ring resonators, configured such that they reflect and spectrally filter light emitted by a diode laser gain material. This causes the diode laser to have a spectrally narrow bandwidth (25 kHz) and widely tunable output (over 40 nm). These lasers are of interest in a variety of scientific and industrial applications. Furthermore, we investigated the possibility of simultaneously control the spectrum and phase of entire arrays of diode lasers. The superimposed output may offer the generation of trains of ultrashort pulses, which is equivalent with the generation of a phase locked comb of equidistant frequencies. The standard method is called mode locking and uses only one gain medium. Because our method uses multiple separate gain media, our method is called separate gain (SEGA) mode locking. Such sources can, for example, be of interest for high-speed optical data storage.