High-Speed Modulation of Optical Injection-Locked Semiconductor Lasers

In this dissertation, we first develop theoretical insight into the nature of resonance frequency and bandwidth enhancement, attempting to correlate the two. We describe the fundamental limit of resonance frequency enhancement and generalize these results to oscillators of all kinds. Using these theoretical trends, we optimized the injection locking performance of 1550 nm distributed feedback lasers. We report a high-speed resonance frequency of 72 GHz and a 3-dB modulation bandwidth of 44 GHz. These are the highest reported resonance frequency and 3-dB bandwidth of any directly-modulated semiconductor laser, respectively.

Direct measurement of laser frequency response is often limited by the bandwidth of photodetectors and network analyzers. In order to measure frequencies above our detection equipment limit (50 GHz), we develop a new optical heterodyne technique that can detect arbitrarily-high modulation frequencies. This technique, in contrast to previous heterodyne methods, does not require stable frequency solid-state lasers and can be used to test telecom-wavelength lasers.

Finally, we discuss a new modulation technique, where the master is modulated rather than the slave. This technique has many applications, such as residual amplitude modulation reduction, frequency modulation regeneration, and frequency discrimination. We demonstrate the latter experimentally, achieving 0.88 mW/GHz frequency-to-amplitude conversion. Additionally, we develop the basis for the theory that governs these techniques and find the theory in good agreement with our experiments.