Optical bistability in an injection-locked vertical cavity surface-emitting semiconductor laser subject to parallel optical injection has been observed. It is shown that the width of the bistability loop may be enhanced by increasing the injection power and the frequency detuning.
Optical frequency bistability and power bistability in semiconductor lasers biased from below to above threshold are presented using the unified description of semiconductor lasers with external light injection. A new method is given to calculate the bistable frequency and power loop widths. When the bias current of a laser is fixed, there is a lowest power for the external light to realize optical frequency bistability. And this lowest power reaches its minimum just at threshold. The optical injection level (defined as the ratio of the injected power to the power emitted by the free-running laser) must be larger than a certain value to obtain the bistability. This level may be larger than unity for a laser biased below threshold. On the other hand, for a given bias current, there is a lowest frequency detuning between the electric field of the laser and the injected field to achieve the power bistability. And this detuning must be negative for any bias current (below or above threshold) of the laser. The results are in good agreement with experiments.>
We have measured optical power and wavelength polarization bistability in a 1550 nm-Vertical Cavity Surface-Emitting Laser (VCSEL) subject to orthogonally-polarized optical injection into the orthogonal polarization of the fundamental transverse mode. Optical bistability with very wide hysteresis cycles, up to four times wider than previously reported results has been measured for both the optical power and wavelength domain. We also report the experimental observation of three different shapes of polarization bistability, anticlockwise, clockwise and X-Shape bistability, all of them with wide hysteresis cycles. This rich variety of behaviour at the important wavelength of 1550 nm offers promise for the use of VCSELs for all-optical signal processing and optical switching/routing applications.
In this paper, we observe experimentally the optical bistability induced by the side-mode injection power and wavelength detuning in a single mode Fabry—Pérot laser diode (SMFP-LD). Results show that the bistability characteristics of the dominant and injected modes are strongly dependent on the injected input optical power and wavelength detuning in an SMFP-LD. We observe three types of hysteresis loops: counterclockwise, clockwise, and butterfly hysteresis with various loop widths. In the case of a bistability loop caused by injection power, the transition from counterclockwise to clockwise in the hysteresis direction with the wavelength detuning from 0.028 nm to 0.112 nm is observed in a way of butterfly hysteresis for the dominant mode by increasing the wavelength detuning. The width of hysteresis loop, induced by wavelength detuning is also changed while the injection power is enhanced from −7 dBm to −5 dBm.
Switching between states in a dispersive bistable injection-locked slave laser has been theoretically investigated. We show that the switching can be achieved by relatively small and short (≈10-50 ps) variation of the master laser injection power or frequency, which, besides the variation of the slave laser optical power, leads to significant variation of its photon phase (≈5π/6). By using an analytical model, we calculate the switching time dependence on the magnitude of the injection power and the frequency detuning variation.