Spin-flip model of spin-polarized vertical-cavity surface-emitting lasers: Asymptotic analysis, numerics, and experiments

The spin-flip model describing optically pumped spin-polarized vertical-cavity surface-emitting lasers is considered. The steady-state solutions of the model for elliptically polarized fields are studied. Asymptotic analysis for the existence and stability of the steady-state solutions is developed, particularly in the presence of pump polarization ellipticity. The expansion is with respect to small parameters representing the ellipticity and the difference between the total pump power and the lasing threshold. The analytical results are then confirmed numerically, where it is obtained that generally one of the steady-state solutions is stable while the other is not. The theoretical results are shown to be in qualitative agreement with the experiments

Investigation of vertical cavity surface emitting laser dynamics for neuromorphic photonic systems

We report an approach based upon vertical cavity surface emitting lasers (VCSELs) to reproduce optically different behaviors exhibited by biological neurons but on a much faster timescale. The technique proposed is based on the polarization switching and nonlinear dynamics induced in a single VCSEL under polarized optical injection. The particular attributes of VCSELs and the simple experimental configuration used in this work offer prospects of fast, reconfigurable processing elements with excellent fan-out and scaling potentials for use in future computational paradigms and artificial neural networks. © 2012 American Institute of Physics

Stability of the nonlinear dynamics of an optically injected VCSEL

Automated protocols have been developed to characterize time series data in terms of stability. These techniques are applied to the output power time series of an optically injected vertical cavity surface emitting laser (VCSEL) subject to varying injection strength and optical frequency detuning between master and slave lasers. Dynamic maps, generated from high resolution, computer controlled experiments, identify regions of dynamic instability in the parameter space. © 2012 Optical Society of America

Nonlinear dynamics of Long-Wavelength VCSELs subject to polarised optical injection

We present our work analysing the effects of polarised optical injection in Long-Wavelength Vertical-Cavity Surface Emitting Lasers (LW-VCSELs). We review the properties of different phenomena such as polarisation switching (PS) and bistability (PB) as well as on the different nonlinear dynamics (periodic and chaotic) arising in these devices under different cases of polarised optical injection. © 2011 IEEE

High frequency continuous birefringence-induced oscillations in spin-polarized vertical-cavity surface-emitting lasers

Sustained, large amplitude and tunable birefringence-induced oscillations are obtained in a spin-vertical cavity surface-emitting laser (spin-VCSEL). Experimental evidence is provided using a spin-VCSEL operating at 1300 nm, under continuous-wave optical pumping and at room temperature. Numerical and stability analyses are performed to interpret the experiments and to identify the combined effects of pump ellipticity, spin relaxation rate, and cavity birefringence. Importantly, the frequency of the induced oscillations is determined by the device’s birefringence rate, which can be tuned to very large values. This opens the path for ultrafast spin-lasers operating at record frequencies exceeding those possible in traditional semiconductor lasers and with ample expected impact in disparate disciplines (e.g., datacomms, spectroscopy)

All-optical inverter based on polarization switching in long-wavelength VCSELs

All-optical processing of high-speed signals is expected to be a key technology in future photonic networks. VCSELs are very promising devices for these applications due to their inherent advantages. Nonlinear transfer functions can be obtained by using optical injection because it strongly affects the transverse mode and polarization characteristics of VCSELs [1]. Optical injection can be used to obtain polarization switching (PS) of single transverse mode VCSELs. When the polarization of an injected optical field is orthogonal to that of the solitary VCSEL (orthogonal optical injection), PS and bistability are observed [2]. PS by optical injection is expected to be fast and thus suitable for application in all-optical signal-processing systems. In this work we report, for the first time to our knowledge, all-optical inversion operation using PS in a 1550nm single-mode VCSEL induced by orthogonal optical injection. We demonstrate all-optical inversion for NRZ signals at a bit rate of 2.5 Gb/s. An all-fiber system has been developed in order to inject the light from a tunable laser into a commercial 1550nm-VCSEL (RayCan, Co.). The free-running VCSEL emits in the fundamental transverse mode with a linear polarization (parallel polarization) over the whole current range. The subsidiary orthogonal polarization is shifted 0.48 nm to the long wavelength side with respect to the dominant one. Pulsed optical injection was obtained by using a pulse pattern generator and a Mach-Zhender intensity modulator. © 2011 IEEE

Simulated dynamics of optically pumped dilute nitride 1300 nm spin vertical-cavity surface-emitting lasers

The authors report a theoretical analysis of optically pumped 1300 nm dilute nitride spin-polarised vertical-cavity surface-emitting lasers (VCSELs) using the spin-flip model to determine the regions of stability and instability. The dependence of the output polarisation ellipticity on that of the pump is investigated, and the results are presented in twodimensional contour maps of the pump polarisation against the magnitude of the optical pump. Rich dynamics and various forms of oscillatory behaviour causing self-sustained oscillations in the polarisation of the spin-VCSEL subject to continuouswave pumping have been found because of the competition of the spin-flip processes and birefringence. The authors also reveal the importance of considering both the birefringence rate and the linewidth enhancement factor when engineering a device for high-frequency applications. A very good agreement is found with the experimental results reported by the authors' group. © The Institution of Engineering and Technology 2014

Optical gain in 1.3-μm electrically driven dilute nitride VCSOAs

We report the observation of room-temperature optical gain at 1.3 μm in electrically driven dilute nitride vertical cavity semiconductor optical amplifiers. The gain is calculated with respect to injected power for samples with and without a confinement aperture. At lower injected powers, a gain of almost 10 dB is observed in both samples. At injection powers over 5 nW, the gain is observed to decrease. For nearly all investigated power levels, the sample with confinement aperture gives slightly higher gain

VCSELs for neuronal dynamics emulation

We report a novel approach based upon Vertical Cavity Surface Emitting Lasers (VCSELs) to reproduce a wide range of dynamics observed in biological neurons on a much faster time scale. © 2012 IEEE