Ana Quirce

Nonlinear dynamics induced by parallel and orthogonal optical injection in 1550 nm Vertical-Cavity Surface-Emitting Lasers (VCSELs)

We report a first experimental study of the nonlinear dynamics appearing in a 1550 nm single-mode VCSEL subject to parallel and to orthogonal optical injection. For the first time to our knowledge we report experimentally measured stability maps identifying the boundaries between regions of different nonlinear dynamics for both cases of polarized injection. A rich variety of nonlinear behaviours, including periodic (limit cycle, period doubling) and chaotic dynamics have been experimentally observed.

High-frequency microwave signal generation using multi-transverse mode VCSELs subject to two-frequency optical injection

In this paper we report a new method of photonic generation of microwave signals using a multi-transverse mode VCSEL subject to two-frequency optical injection. Numerical simulations show that double injection locking involving two transverse modes can be obtained in these systems. We show that the higher-order transverse mode is excited with a much larger amplitude than that of the fundamental transverse mode. The comparison with the case of a single-transverse mode VCSEL subject to similar two-frequency optical injection shows that multi-transverse mode operation of the VCSEL enhances the performance of the photonic microwave generation system. Broad tuning ranges, beyond the THz region, and narrow linewidths are demonstrated in our system. The maximum frequency of the generated microwave signals can be substantially increased if multimode VCSELs are used instead of single-mode VCSELs.

Polarization Switching in Long-Wavelength VCSELs Subject to Orthogonal Optical Injection

Polarization switching (PS) appearing in long-wavelength vertical-cavity surface-emitting lasers (VCSELs) subject to orthogonal optical injection is investigated theoretically and experimentally. We have studied the injected optical power required for PS as a function of the frequency detuning between the injected light and the orthogonal linear polarization of the VCSEL. For a wide range of bias currents applied to the device, the injected power required for the occurrence of PS exhibited a minimum and a plateau with respect to the frequency detuning. The minimum (plateau) was found at negative (positive) frequency detuning. The bistable behavior of the polarization is described. Our experimental results confirm the theoretical predictions of Sciamanna and Panajotov. The levels of the minimum and the plateau were observed to increase as higher bias currents were applied to the VCSEL. A first theoretical and experimental observation of the disappearance and further appearance of PS when increasing the injected power in long-wavelength VCSELs is described. This situation is obtained for small levels of negative frequency detuning and for large enough values of applied bias current. A good overall qualitative agreement is found between our theoretical and experimental results.

Power and wavelength polarization bistability with very wide hysteresis cycles in a 1550nm-VCSEL subject to orthogonal optical injection

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.

Very Wide Hysteresis Cycles in 1550-nm VCSELs Subject to Orthogonal Optical Injection

A first experimental observation of three different types of frequency-induced polarization bistabilities in 1550-nm single transverse and polarization mode vertical-cavity surface-emitting lasers (VCSELs) subject to orthogonal optical injection is described. The hysteresis width of the bistable region that appears at longer wavelegth detunings increases as the injected power or the VCSEL current increases. Very large hysteresis widths are obtained. These widths are more than seven times larger than previously reported widths.

Polarization switching and injection locking in vertical-cavity surface-emitting lasers subject to parallel optical injection.

Polarization switching in a long-wavelength vertical-cavity surface-emitting laser (VCSEL) under parallel optical injection is analyzed in a theoretical and experimental way. For the first time, to our knowledge, we report experimentally a state in which injection locking of the parallel polarization and excitation of the free-running orthogonal polarization of the VCSEL are simultaneously obtained. We obtain very simple analytical expressions that describe both linear polarizations. We show that the power of both linear polarizations depend linearly on the injected power in such a way that the total power emitted by the VCSEL is constant. We perform a linear stability analysis of this solution to characterize the region of parameters in which it can be observed. Our measurements qualitatively confirm the previous theoretical predictions.

Polarization Bistability Induced by Orthogonal Optical Injection in 1550-nm Multimode VCSELs

We have analyzed experimentally the optical power polarization bistability induced in a long-wavelength multitransverse mode vertical-cavity surface-emitting laser (VCSEL) under orthogonal optical injection. Bistability with very wide hysteresis cycles is measured for both the fundamental and the high-order transverse mode of the device. The shape of the associated hysteresis cycle is different for each of the two transverse modes. The power of the parallel polarized high-order (fundamental) transverse mode remains constant (gradually decreases) as the injected power is increased. Both powers suddenly drop to low levels at large values of the injected power. The squared shape measured for the I/O characteristic of the high-order transverse mode is of particular interest for obtaining good quality all-optical inversion and all-optical regeneration for use in optical telecommunication networks.

Photonic Generation of Microwave Signals Using a Single-Mode VCSEL Subject to Dual-Beam Orthogonal Optical Injection

We experimentally and theoretically investigate the photonic generation of microwave signals using a long-wavelength single-transverse-mode vertical-cavity surface-emitting laser (VCSEL) subject to two-frequency orthogonal optical injection. We study if a significant reduction of the linewidth is achieved in the double injection locking regime. In this regime, the VCSEL is subject to optical injection by two master lasers in such a way that stable locking is also observed if only light from one of the master lasers is injected. Our model includes the effect of the injected light reflected at the VCSELs mirror generalizing previous modeling of reflection-mode optical injection-locked VCSELs. Our model also describes the high coherence associated to stable injection locking states and takes into account phase fluctuations in both master lasers. We observe no significant reduction of the linewidth in the double injection locking regime because the linewidth is mainly determined by the phase fluctuations of the two master lasers.

All-Optical Inverter Based on Polarization Switching in VCSELs Subject to Single and Dual Optical Injection

All-optical inversion in single-mode vertical-cavity surface-emitting lasers (VCSELs) under single- and dual-polarized optical injection is numerically analyzed. For single optical injection, turn-on delay of the parallel polarized power and spikes of the orthogonally polarized power are similar to those found when gain-switching a multimode semiconductor laser. We consider two different methods for all-optical inversion using dual-polarized optical injection. In the first (second) method, pulses of orthogonally (parallel) polarized light and a CW parallel (orthogonally) polarized beam are injected into the VCSEL. Similar switching times and extinction ratios are obtained with both methods. Faster operation with any of these two methods is obtained than for single injection. We show that both types of dual optical injection produce all-optical inversion and all-optical gating with similar characteristics. All-optical gating and inversion are achieved for a 2.5 Gb/s NRZ signal.

Polarization-Resolved Nonlinear Dynamics Induced by Orthogonal Optical Injection in Long-Wavelength VCSELs

We report a first experimental study of the polarization-resolved nonlinear dynamics of a 1550 nm single-mode vertical-cavity surface-emitting laser (VCSEL) subject to orthogonal optical injection. Stability maps identifying the boundaries between regions of different nonlinear dynamics are reported for two different values of the bias current. A rich variety of nonlinear behaviors including periodic, period doubling, and irregular dynamics are observed for both polarizations. Polarization switching and injection locking induced by the optical injection are also included in the mapping. Analysis is given also in terms of the frequency detuning between the injected light and the orthogonal linear polarization of the VCSEL. When the frequency detuning is positive polarization switching can be observed in a periodic dynamical regime, including both period one and period two behaviors. For positive frequency detuning, the only polarization that contributes to the dynamics of the total power is the orthogonal polarization. For negative frequency detunings both linear polarizations contribute to the dynamics of the total power.