Transfer-matrix analysis of optical bistability in DFB semiconductor laser amplifiers with nonuniform gratings

Abstract

We present a transfer-matrix method capable of simulating the effects of nonuniform gratings on the filtering, amplification, and bistability characteristics of distributed feedback (DFB) semiconductor laser amplifiers. The linewidth enhancement factor is incorporated in a way that allows direct gaintuning of the bistability hysteresis. As an example, we compare a /4 phase-shifted DFB amplifier with and without spatial chirp. For amplifiers driven to yield the same unsaturated peak amplifier gain, positive linear chirp widens the spectral range of low-threshold switching and increases the switching contrast.

Two-wavelength switching with a distributed-feedback semiconductor optical amplifier (DFBSOA)

“…Under external optical power injection, owing to the change in the refractive index and the saturation of gain, the resonant cavity wavelength of the laser amplifier moves towards longer wavelengths depending on the amount of the injected power, and exceeding a threshold value the optical bistability can be observed [17,18]. In the past, the dispersive optical bistability has been studied in FPSLAs [17][18][19][20][21] in DFBSOAs [22][23][24] and more recently in vertical-cavity semiconductor optical amplifiers (VCSOAs) [25,26]. The optical bistability has been analysed when the amplifier is operated either in transmission or in reflection, and the differences in behaviour for each mode of operation have been determined [21,27].…”

Bistability patterns and nonlinear switching with very high contrast ratio in a 1550 nm quantum dash semiconductor laser

“…[11][12][13][14][15] The latter showed anticlockwise OB with very wide hysteresis cycles, even for low values of initial detuning and for applied bias currents very close to threshold or below that level. [11][12][13] Furthermore, for edge-emitting devices biased above threshold, anticlockwise OB had only been reported, 13 while the occurrence of clockwise or other types of bistability has only been measured when biased below threshold.…”

“…These include all-optical logic gates, [3][4][5] all-optical flip-flop, 6 optical signal regeneration, 7 optical switching, 8 wavelength conversion, 9 optical buffer memory, 10 etc. The range of laser structures where OB and NS has been investigated includes devices with bulk or quantum-well (QW) active regions, such as edge-emitting lasers, Fabry-Perot (FP) [11][12][13] and distributed feedback (DFB) 8,14,15 and also vertical-cavity devices, i.e., vertical cavity surface emitting lasers (VCSELs), 16,17 and vertical cavity semiconductor optical amplifiers (VCSOAs) [18][19][20] (for a review see Refs. 1 and 2 and references therein).…”

“…These record values of reflective optical power switching and bistability are at least one order of magnitude higher than any previously reported for other types of semiconductor lasers and laser amplifiers including bulk or quantum well edge-emitting or verticalcavity devices. [11][12][13][14][15][16][17][18][19] We must note that the peak power of the reflective signal was used to determine the on-off contrast ratio. We believe that this technique is in fact conservative.…”

Optical bistable devices as sensing elements

“…The advantage of DFB laser diode is clear on optical communications, important bistability reports on transmission and reflection configuration, both needed for our sensor device can be found on [13][14], We have also analysis how respond a DFB laser on our basic structure, used by as for optical computing 15 and sensors. A comparison between noise present in a DFB and FP laser structure can be found on [16].…”