The intracavity gain dynamics of an external cavity semiconductor hybrid mode-locked laser are measured under
three wavelength operation. The results show a partial coherence and a temporal skew among pulses corresponding to
different wavelength channels. The temporal skew broadens the temporal pulse profile and the partial coherence
decreases the temporal beating between wavelength channels. A measurement of the temporal evolution of the gain
reveals a slow gain depletion, avoiding nonlinearities, and gain competition between wavelength channels, making
multiwavelength operation feasible.
Spectrally resolved interferometry combining up-chirped and down-chirped pulses allows for millimeter range
resolution in laser ranging applications. Key in our approach is the use of temporally stretched optical pulses of 5
nanoseconds in duration. These stretched pulses were obtained from a femtosecond semiconductor mode-locked laser
and were up-chirped and down-chirped using a chirped fiber Bragg grating and recombined to realize spectral
interferometry. This approach provides a means to achieve the high pulse energies required for a laser radar application
which are easy to achieve using nanosecond pulses but maintains the high spatial resolution associated with
femtosecond optical pulses.
The gain dynamics of a semiconductor optical amplifier (SOA) are studied for the amplification of long, short and multiwavelength pulses from an external cavity semiconductor mode-locked laser. Nonlinear effects such as carrier heating and cooling, four wave mixing, and self phase modulation are observed, and it is shown how the inherent chirp of semiconductor mode-locked laser pulses helps to avoid these nonlinear effects.
A novel dispersion-managed breathing-mode mode-locked semiconductor ring laser is studied. The working regime and pulse evolution at the key cavity points are experimentally characterized and numerically simulated. Linearly chirped, asymmetric exponential pulses are generated, suitable for external amplification and compression. The pulses are externally compressed to duration as short as 274 fs, which is within 10% of the bandwidth limit. The close agreement between the simulated and the measured results verifies our ability to control the physical mechanisms involved in pulse formation and shaping within the ring cavity.