Robust square-wave polarization switching in vertical-cavity surface-emitting lasers

Abstract

We study theoretically and experimentally the combined effects of polarization-selective optical feedback and of crossed-polarization reinjection in a vertical-cavity surface-emitting laser. We show that the application of polarization-selective optical feedback, which induces an effective dichroism in the system, allows one to generate a robust and regular square-wave output signal in each polarization component. The period of the square-wave signal is determined by twice the reinjection delay. We analyze the regularity of the induced modulation as a function of laser bias current, dichroism, and of the levels and delays of reinjection and feedback, thus revealing the robustness of the square-wave emission in the parameter space. We also show that the feedback is more effective when acting on the long-wavelength polarization mode, which can be traced to the asymmetry of the bistable region of the vertical-cavity surface-emitting lasers for low dichroism.

All-optical controlled switching between time-periodic square waves in diode lasers with delayed feedback

“…4(b) and 4(c). When θ τ, fast oscillations are found as it was the case for a VCSEL with the same setup [10]. The switching from P 0 to a given P n is obtained by changing γ from 0 to 0.005.…”

“…When part of the light emitted by a semiconductor laser is reflected back into the laser after a substantial delay, a rich variety of pulsating outputs can be observed. Among the diverse setups studied experimentally, the laser subject to polarization rotated optical feedback (PROF) is particularly attractive [4][5][6][7][8][9][10]. It has found a variety of applications stemming from alloptical production of high frequency pulses [11] and from its chaotic behavior for random bit generation [12].…”

“…The multistability phenomenon is observed for many nonlinear systems and the transition of complex multistability to controlled monostability has raised a lot of attention [14,15]. For Vertical-Cavity Surface-Emitting Lasers (VCSELs) with the PROF setup, it was recently shown that a second weak feedback allows generation of robust SWs with respect to parameter changes [10]. By adding this second feedback with a delay time θ, we experimentally demonstrate that at fixed θ, we may switch from the main P 0 state to a specific P n state by simply increasing the feedback amplitude.…”

Square-wave oscillations in a semiconductor ring laser subject to counter-directional delayed mutual feedback

“…Utilizing external laser sources, SW generation has been investigated based on chromatic dispersion of mode-locked pulses, bistabilities in semiconductor optical amplifiers, and nonlinearities in optoelectronic oscillators [19][20][21][22]. SW generation has also been generated directly on the output signal of a laser source by polarization-switching in edge-emitting lasers [13][14][15] and in vertical-cavity surface emitting lasers [16][17][18].…”

“…SW optical signals are needed as clocks in signal processing and communication systems [13][14][15][16][17][18][19][20][21][22][23]. Utilizing external laser sources, SW generation has been investigated based on chromatic dispersion of mode-locked pulses, bistabilities in semiconductor optical amplifiers, and nonlinearities in optoelectronic oscillators [19][20][21][22].…”