Limitations on ultrafast optical switching in a semiconductor laser amplifier operating at transparency current

Ultrafast optical switching in a semiconductor laser amplifier (SLA) at transparency current is studied under a strong pump condition. The switch configuration is a nonlinear optical loop mirror with a SLA as the nonlinear element. We demonstrate optical switching with 2 ps recovery time and 60% nonlinear transmission at switching energy of 9 pJ. We find that the transparency current is pump power dependent and that the transparency current is different for uniform 7-bit input control pulses at 100 Gb/s. We believe these two outcomes are due to significant carrier generation via two photon absorption (TPA) at high pump intensity. To verify our hypothesis, we modify coupled propagation equations by including the carrier generation due to the TPA and solve the equations numerically. Good agreement between the experimental and simulation results is obtained. We conclude that to achieve complete pattern-independent 100 Gb/s optical switching using a SLA at transparency current, we have to avoid TPA or use the SLA with a transit time shorter than the control pulse width. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70958/2/JAPIAU-86-9-4740-1.pd

Gain dispersion induced subpicosecond pulse breakup in a fiber and semiconductor laser amplifier combined system

We observe pulse breakup for 650‐fs pulses propagating through 9 m of optical fiber followed by an InGaAsP amplifier. The pulses are broadened by a factor of two, and a second peak appears at about 2 ps after the main peak. To identify the responsible mechanisms, we solve numerically the propagation equations including nonlinear carrier dynamics and gain dispersion. We attribute the broadening to two photon absorption and the breakup to the interplay between linear gain dispersion and frequency chirp in the amplifier. These pulse distortions could impact devices involving fibers and semiconductor amplifiers for high speed (>200 Gb/s) optical switching or transmission. © 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69518/2/APPLAB-69-27-4221-1.pd