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The presentation will describe experimental work which illustrates novel features of VCSELs subje... more The presentation will describe experimental work which illustrates novel features of VCSELs subject to external optical interrogation. Attention will be given to (i) the effects of circularly polarized optical feedback; (ii) the role of the suppressed mode in VCSEL switching and (iii) polarization switching and hysteresis in optically injected VCSELs. Some attention may also be given to properties of nano-lasers.

The study of the polarization properties of vertical cavity surface emitting lasers (VCSELs) has ... more The study of the polarization properties of vertical cavity surface emitting lasers (VCSELs) has been a topic of active research not least due to polarization- dependent applications of such devices. VCSELs usually exhibit a linearly- polarized emission along one of two orthogonal polarization directions.

Polarization switching (PS) characteristics in vertical cavity surface emitting lasers (VCSELs) h... more Polarization switching (PS) characteristics in vertical cavity surface emitting lasers (VCSELs) have been studied experimentally. The role of the suppressed mode of VCSELs in reducing the injected optical power (Pinj) required for PS has been identified. For orthogonal optical injection the minimum Pinj to induce PS was found to occur at a frequency detuning (FD) of -11 GHz corresponding to the VCSEL birefringence. The Pinj reduced significantly with increasing bias current.

The output polarization of vertical cavity surface emitting lasers (VCSELs) has been investigated... more The output polarization of vertical cavity surface emitting lasers (VCSELs) has been investigated experimentally using external optical injection. The frequency, intensity and polarization state of the injected beam will determine how the parameters of the VCSEL are changed. The polarization of the VCSEL emission can be changed from linear horizontally polarized to a circularly or elliptically polarized state using low power circularly polarized optical injection, with frequency detuning around -10 GHz with respect to the slave laser frequency at threshold. In addition the optical injection will reduce the threshold lasing current compared to that of the stand-alone VCSEL.

2013 Conference on Lasers and Electro-Optics Pacific Rim (CLEOPR), 2013

Polarization bistability in VCSEL subject to orthogonally polarized optical injection is studied ... more Polarization bistability in VCSEL subject to orthogonally polarized optical injection is studied experimentally. It is shown that the VCSEL may exhibits a low power (2.8 µW) polarization switching and ultra-wide hysteresis cycle beyond 150 GHz.

IEEE Photonics Technology Letters, 2000

We report experimental observations of robust irreversible polarization switching (IPS) in vertic... more We report experimental observations of robust irreversible polarization switching (IPS) in vertical cavity surface emitting lasers (VCSELs) subject to external optical injection. It is shown that, when operated in a two-mode regime, the VCSEL exhibits IPS for both parallel and orthogonal optical injection. The polarization switching is maintained for a wide range of values of control parameters, including frequency detuning, injected power (P inj ), bias current, and device operating temperature.

IEEE Journal of Quantum Electronics, 2000

Polarization switching characteristics of birefringent vertical cavity surface emitting lasers (V... more Polarization switching characteristics of birefringent vertical cavity surface emitting lasers (VCSELs) subject to polarized optical injection are investigated experimentally. The role of the suppressed mode of VCSELs in reducing the injected optical power required for polarization switching (PS) has been identified. For orthogonal optical injection, the minimum optical injection power (P inj ) to induce PS is found to occur at a frequency detuning (FD) of −11 GHz corresponding to the VCSEL birefringence. The value of the minimum P inj reduced significantly with increasing bias current. The FD for PS is independent of the VCSEL bias current, injected power level, and a defined range of polarization angles of the injected light. However, for parallel optical injection, the minimum FD for PS is normally found to be positive and dependent on the VCSEL bias current and injected optical power.

Composites Engineering, 1995

Applied Physics Letters, 2013

ABSTRACT We report experimental observations of an ultra-wide frequency hysteresis in vertical ca... more ABSTRACT We report experimental observations of an ultra-wide frequency hysteresis in vertical cavity surface emitting lasers subject to orthogonal optical injection. Polarization bistability and its associated hysteresis are studied by increasing and decreasing the frequency detuning for a fixed injection power when the device operated at high bias current I>2Ith. The results show that an ultra-wide hysteresis width of about 155 GHz is obtained for positive frequency detuning. The width of the frequency hysteresis is more than four times larger than all previously reported widths.

IEEE/OSA Journal of Lightwave Technology, 2011

This paper reports experimental investigations of the effects of circularly polarized optical inj... more This paper reports experimental investigations of the effects of circularly polarized optical injection on the lasing characteristics of vertical-cavity surface-emitting lasers (VCSELs). The operating characteristics of the target VCSELs are changed using available optical injection control parameters including the strength and polarization state of the optical injection as well as the frequency detuning between the injected light and the target VCSEL. Using circularly polarized optical injection with frequency detuning around -10 GHz, the linear output polarization of the stand-alone VCSEL can be converted into circularly polarized or elliptically polarized emission when the VCSEL drive current is close to or below the threshold current of stand-alone VCSEL. In addition, highly nonlinear light-current characteristics are observed in the optically injected VCSEL in the vicinity of threshold.

IEEE Photonics Technology Letters, 2012

This letter investigates experimentally the effects of circularly polarized optical feedback (CPO... more This letter investigates experimentally the effects of circularly polarized optical feedback (CPOF) on the polarization characteristics of vertical-cavity surface-emitting lasers (VCSELs). It is shown that CPOF imparts up to 30% circular polarization to the VCSEL emission. The degree of circular polarization acquired by the VCSEL emission is determined by the feedback power ratio and the VCSEL bias current. The effects of COPF have been compared to the influence of other species of linearly polarized optical feedback.

Optics Letters, 2010

Thermal effects and dynamical hysteresis in VCSELs under dc modulation have been experimentally s... more Thermal effects and dynamical hysteresis in VCSELs under dc modulation have been experimentally studied. The results show that the VCSEL turn-on and turn-off currents can display both positive hysteresis and negative hysteresis, depending on the current modulation frequency and on the substrate temperature. Numerical simulations of semiconductor laser rate equations, extended to take into account thermal effects, show a good agreement with the observations.