Polarization control of vertical-cavity surface-emitting lasers by electro-optic birefringence (original) (raw)
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IEEE Journal of Selected Topics in Quantum Electronics, 1995
Polarization of vertical-cavity surface-emitting lasers ͑VCSELs͒ grown on ͑001͒ GaAs substrate has been controlled by electro-optic birefringence. Birefringence was induced at the top distributed Bragg reflector by applying an electric field along the ͓001͔ direction. The cavity resonance of the polarized light along the ͓110͔ or ͓110͔ direction shifted to shorter and longer wavelength, depending on the direction of the applied electric field. By varying the direction and strength of the electric field, we actively controlled the polarization of VCSELs. The dominant polarization mode occurred along the ͓110͔ direction for the negative electric field, and along the ͓110͔ direction for the positive electric field.
Control of Polarization Switching in Vertical Coupled-Cavities Surface Emitting Lasers
IEEE Photonics Technology Letters, 2004
We report a novel three-contact vertical-cavity surface-emitting laser (VCSEL) for use in polarization-sensitive optical applications. The device consists of two vertical cavities, coupled by a common mirror. We demonstrate that one can independently choose both the power of the output beam-through the current in the first cavity-and the polarization state-through the bias applied to the second cavity. The control of the polarization state is performed with a control voltage in the range -2 to 0 V. Within this interval, the structure exhibits a bistable behavior. We present the very first experimental proof of nonthermal, electrically induced polarization switching in coupled-cavities VCSELs.
Applied Optics, 2009
Influences of variable-angle polarization-rotated optical feedback on polarization properties of verticalcavity surface-emitting lasers (VCSELs) are investigated numerically. For the so-called case A (x polarization) feedback, only the x mode is selected to pass through the feedback loop. As the polarization angle is varied from 0°to 90°, the dominant polarization mode switching can be observed even for fixed feedback strength and bias current. For the so-called case B (xy polarization) feedback, the total outputs of the VCSEL pass through the feedback loop. The polarization property is much different from case A. The dominant polarization mode switching occurs not in the entire range of polarization angles, however, but in the so-called critical angle, from where the intensities of both polarization modes become comparable to each other and keep around constant values, and can be observed. In addition, the complementary properties of intensities between the two polarization modes for both cases are evaluated quantitatively in terms of the defined normalized intensity.
Polarization characteristics, control, and modulation of vertical-cavity surface emitting lasers
SPIE Proceedings, 1995
The gain-dependent polarization properties of vertical-cavity sdace emitting lasers and methods for polarization control and modulation are discussed. The partitioning of power between the two orthogonal eigen polarizations is shown to depend upon the relative spectral alignment of the nondegenerate polarization cavity resonances with the laser gain spectrum. A dominant polarization can thus be maintained by employing a blue-shifted offset of the peak laser gain relative to the cavity resonance wavelength. Alternatively, the polarization can be controlled through use of anisotropic transverse cavity geometries. The orthogonal eigen polarizations are also shown to enable polarization modulation. By exploiting polarization switching transitions in cruciform lasers, polarization modulation of the fundamental mode up to 50 MHz is demonstrated. At lower modulation frequencies, complementary digital polarized output or frequency doubling of the polarized output is obtained. Control and manipulation of vertical-cavity laser polarization may prove valuable for present and future applications.
Electro-optic effect and birefringence in semiconductor vertical-cavity lasers
Physical Review A, 1997
Semiconductor vertical-cavity surface-emitting lasers ͑VCSELs͒ are known to exhibit a small amount of birefringence. We present a model that enables us to estimate how much of this is due to the electro-optic effect produced by the inevitable internal electric field in working devices. Of vital importance for this model is the notion that the position-dependent changes in the refractive index should be weighted by the local optical intensity both in the spacer as well as in the distributed Bragg reflectors. Index variations in the optical nodes thus go unnoticed, whereas those in the antinodes can strongly affect the cavity resonance. This is related to the idea that the active quantum wells in a VCSEL should be positioned in optical antinodes to produce the highest modal gain. The results of our model calculation are compared with statistical data on the magnitude and orientation of the measured birefringence in planar proton-implanted VCSELs. These data show the presence of a systematic contribution to the birefringence, which can presumably be attributed to the electro-optic effect, and a random contribution, which we attribute to stress and strain. ͓S1050-2947͑97͒01407-8͔
Applied Physics Letters, 2003
We propose and demonstrate a long-wavelength vertical cavity surface emitting laser ͑VCSEL͒ which consists of a ͑311͒B InP-based active region and ͑100͒ GaAs-based distributed Bragg reflectors ͑DBRs͒, with an aim to control the in-plane polarization of output power. Crystal growth on ͑311͒B InP substrates was performed under low-migration conditions to achieve good crystalline quality. The VCSEL was fabricated by wafer bonding, which enables us to combine different materials regardless of their lattice and orientation mismatch without degrading their quality. The VCSEL was polarized with a power extinction ratio of 31 dB.
Applied Physics Letters, 1997
We report that the 780 nm quantum well vertical-cavity surface-emitting lasers ͑VCSELs͒ grown on a 2°off misoriented ͑001͒ substrate toward ͑111͒A exhibit a high polarization suppression ratio over a few hundred. The main polarization is always along the ͓Ϫ110͔ direction for all the lasers over the entire operating currents. To understand the physical origin of this polarization selectivity, the gain/loss difference between two competing polarization modes in VCSELs is investigated by measuring the subthreshold spectral linewidth. The obtained modal gain/loss difference is about 3.0 cm Ϫ1 , which is sufficiently large for polarization stabilization and amounts to 4% of the threshold modal gain. Comparison with the subthreshold measurement and previous theoretical work shows significant discrepancy, which implies the possibility of other polarization selection mechanisms inducing such large gain/loss differences in 780 nm quantum wells grown on a misoriented substrate. In addition, it is found that the 780 nm VCSEL made of a bulk active medium grown on a misoriented substrate also shows a high polarization selectivity as quantum well lasers.
Applied Physics Letters, 1997
In the literature different models have been presented to study polarization switching (PS) in vertical-cavity surface-emitting lasers (VCSELs). In this work we have studied two of them: the so-called Spin Flip Model due to San Miguel, Feng and Moloney (SFM), attributing PS to specific amplitude-phase coupling, and the more phenomenological Gain Saturation Model (GSM), attributing PS to linear and non-linear gain effects. By careful use of a multiple-time scale technique we have thrown a bridge between the SFM and GSM models in the parameter domain of high spin-flip rate and large birefringence. This link has been used to discuss the similarities and differences between both models.
Investigation of polarization switching of VCSEL subject to intensity modulated and optical feedback
Optics & Laser Technology, 2015
ABSTRACT This study presents the results of an experimental investigation of the polarization switching (PS) of vertical-cavity surface-emitting lasers (VCSELs) using the so-called polarization-rotated optical feedback mechanism. In particular, the experiments is performed by changing the laser driving current, optical feedback (OF) level, modulation signal parameters, such as frequency, modulation-depth in order to assess their influences on the PS of VCSEL. We show that a smaller polarization angle θ p is required to realize PS with increasing the level of OF. Moreover, for a fixed OF level and increased bias current a smaller θ p is required to ensure PS. However, for a fixed OF and variable modulation parameters, both the frequency and modulation-depth lead to the elimination of PS over the entire range of measurement.