| Semiconductor lasers have been one of the major building blocks of fiber-optics based communication systems. For the past two decades, specifications of these lasers have been tailored to particular applications by defining certain performance parameters that do not necessarily overlap from one application to another. In order to commoditize laser sources by increasing volume and reducing cost, the laser performance parameters needed to be generic and not customized. In this simulation work, we modify and enhance essential performance parameters of a simple, low-cost laser with generic specifications and tailor it to specific applications that normally require advanced and complicated laser structures, by using electronic feedback for instantaneous impairment correction, while at the same time maintain a compact size for the laser and the supporting circuitry around it. We essentially use the same laser chip to cover the three distinct applications being analyzed. Maintaining generic laser chip specifications while only modifying the feedback loop circuit design parameters can facilitate photonic hybrid integration. Specific applications targeted are, linear optical-analog transmission for wireless backhauling by reducing the laser relative intensity noise while maintaining and enhancing transmitter linearity, improving laser modulation response and increasing the laser relaxation-oscillation frequency, another application covers laser linewidth reduction to target long haul transmission and coherent detection and finally an application that requires producing a self-pulsating laser for analog to digital conversion sampling application. The performance for all these application is analyzed in both the time and frequency domains. For the analog-signal laser, a laser RIN reduction of 15 dB was realized in the simulation and experiment. For the linewidth-reduction application, the simulation also shows a reduction of linewidth from 2.4 MHz to 24 Hz can be achieved along with simultaneous reduction of 1/f noise at low frequencies, and carrier effect noise at high frequencies to flatten the laser FM response. As for the pulse-generation application, an analysis on controlling the self-pulsation characteristics of semiconductor DFB laser was performed. A detailed analysis of the noise effects on the jitter performance of this system is also carried out. This work also establishes methods to optimize and control a pulsing DFB-laser system for photonic analog-to-digital conversion application by tuning the laser drive current with the potential to replace mode-locked fiber lasers in many applications from RF photonics to chaos communication and optical signal processing. |
