Injection power and wavelength dependence of an external-seeded gain-switched Fabry–Perot laser

Abstract

We experimentally investigate a gain-switched Fabry–Perot semiconductor laser externally injection seeded with a narrow linewidth continuous wave laser. We determine the dependence of pulse width, side-mode suppression ratio, and timing jitter on seeding power and seeding wavelength. As external seeding power is increased up to a certain value, we observe negligible change in pulse width, a linear increase in side-mode suppression ratio, and a linear decrease in timing jitter. Exceeding a certain value leads to substantial pulse broadening. By tuning the seeding wavelength across a chirped mode of the laser, we observe the lowest timing jitter and the largest side-mode suppression when the seed wavelength is aligned with the center of the chirped spectrum of a desired mode.

Frequency dynamics of gain-switched injection-locked semiconductor lasers

“…The lower values corresponded to a master laser completely tuned to the slave emission frequency, and symmetrical detunings around the zero value gave the same results for the PDF of turn-on times. Experimental verification of this behavior as a function of the frequency detuning has been reported in agreement with the theoretical results [31], [32]. Additional experimental observations were a linear increase in the SMSR and pulse broadening, specially noticeable at high injection levels.…”

Characterization of 1.55-μm pulses from a self-seeded gain-switched Fabry-Perot laser diode using frequency-resolved optical gating

“…Significantly, the FROG measurements show that whilst the chirp is highly nonlinear at low SMSR, it becomes increasingly linear with increasing SMSR. The reduction in the chirp magnitude with increasing reinjection has been noted previously [12], [13] and arises since the presence of the reinjected signal reduces the peak inversion reached during the pulse emission process. To the best of our knowledge, the results presented here are the first direct measurements of the change in chirp across the pulse with reinjection level, and the first to demonstrate improved linearity with increased reinjection.…”

“…Within experimental error, the average output power was measured at around 0.17 mW for all SMSR values. At estimated reinjection levels greater than 6%, pulse deformation and instabilities were observed [12], although a comprehensive analysis of this operating regime was not carried out in our experiments. Fig.…”

Complete characterization of ultrashort pulse sources at 1550 nm

“…With varying reinjection level, the side-mode supression ratio (SMSR) between the lasing mode and adjacent modes was observed to vary significantly, and stable laser operation was observed for SMSR values from 15 to 35 dB (corresponding to estimated reinjection levels of 0.1%-6%). Higher reinjection levels resulted in instabilities [36]. Fig.…”