Improvement of the wavelength switching behavior of semiconductor tunable lasers through optical feedback from a periodic reference filter based on a novel prism-based implementation of a Fox-Smith resonator

We show that the wavelength switching behavior of semiconductor tunable lasers can be improved through optical feedback from a stable reference filter. The filter is based on a novel prism-based implementation of a Fox-Smith resonator and has a response consisting of periodically spaced peaks, both in reflection and transmission. The improvement of the wavelength switching behavior stems from the suppression of the thermally induced wavelength drift associated with the switching of the tuning currents.     

Degradation of the mode suppression in single-mode laser diodes due to integrated optical amplifiers

We show that the side-mode suppression in single-mode laser diodes, such as DFB or distributed Bragg reflector laser diodes, can be reduced by 10 dB or more if an optical amplifier is integrated with the laser diode. The reduction of the side-mode rejection is due to an increase of spontaneous emission that couples into the side mode, an increase which in turn is due to amplified spontaneous emission originating in the optical amplifier.     

A λ/4-shifted sampled or superstructure grating widelytunable twin-guide laser

A novel widely tunable laser diode that only requires two tuning currents is proposed. The laser structure is based on the tunable twin-guide laser with a λ/4-shifted sampled or superstructure grating. Numerical simulation results are given for the tuning characteristics     

Intensity noise and linewidth of laser diodes with integrated semiconductor optical amplifier

It is shown that the relative intensity noise and the linewidth of a laser diode can increase significantly if an optical amplifier is integrated with the laser diode. This increase is due to the amplified spontaneous emission from the optical amplifier.     

Improvement of the direct modulation behavior of semiconductor lasers by using a holding beam

We show theoretically that the direct modulation properties of semiconductor lasers can be significantly improved by the injection of a so-called holding beam-a continuous-wave beam at the transparency wavelength of the gain medium. Both the small-signal and the large-signal behavior are investigated.