Polarization Of Vertical-cavity Surface-emitting Lasers Research Articles

Memory effect for polarization of pump light in optically pumped vertical-cavity semiconductor lasers

We report that the polarization of the emission of an optically pumped vertical-cavity surface-emitting laser (VCSEL) is sensitive to the polarization state of the pump light. By measuring this memory effect for circularly polarized pump light, we determine the normalized relaxation rate of the carrier spin, /spl Gamma//sub s/, which is a vital parameter in current theoretical models of VCSEL polarization. We find /spl Gamma//sub s/=300/spl plusmn/150, a value which is significantly larger than previously estimated. We also observe a memory effect for the orientation of linearly polarized pump light. This signals that, apart from the carrier spin, the VCSEL polarization is also determined by the carrier momentum.

<inline-formula>16×16</inline-formula> self-routing cell switch using polarization-controlled vertical cavity surface emitting laser arrays: principles

The principle and design of a self-routing 16316 free-space optically interconnected crossbar cell switch are detailed. Vertical cavity surface emitting lasers (VCSELs) and VCSEL-based smart pixel arrays are key devices for this system and enable high density interconnection. Using the optical switching of VCSEL polarization extensively, the cell switch exhibits a potential high bit rate and low reconfiguration time be- tween two cells. Moreover, because of the high speed switching of the VCSEL between its two linear polarizations, address substitution, which is one of the asynchronous transfer mode (ATM) requirements, can be implemented. A compact cell-switch demonstrator is proposed that uses low-cost optically recorded holograms and microlens arrays. © 1997 So- ciety of Photo-Optical Instrumentation Engineers. (S0091-3286(97)03011-0) Subject terms: cell switch; polarization-controlled vertical cavity surface emitting lasers (VCSELs); VCSEL-based smart pixels; free-space interconnections; opti- cally recorded holograms.

Lasing characteristics of GaAs(311)A substrate based InGaAs-GaAs vertical-cavity surface-emitting lasers

An experimental investigation of lasing characteristics in InGaAs-GaAs vertical-cavity surface-emitting lasers (VCSELs) grown on GaAs(311)A substrates is presented. To improve temperature characteristics, the gain peak wavelength was detuned by -33 mm from the VCSEL cavity mode. It was found that anisotropic in-plane gain distribution in (311)A-oriented quantum wells (QWs) effectively controls polarization of VCSELs. A stable polarization mode was always exhibited along the [233] direction, which corresponds to the crystallographic axis of maximum gain for (311)-oriented QWs, The [233] polarization mode was maintained against injection currents of more than 2.5 times the threshold over the wide temperature range of 25/spl deg/C to 150/spl deg/C. The orthogonal [011] polarization mode was completely suppressed, and an suppression ratio of 19.8 dB between two orthogonal polarization modes was obtained at 1.8 times the threshold current at 80/spl deg/C, the temperature at which the gain peak matches the cavity mode. In addition, a threshold current of 680 /spl mu/A and a corresponding threshold current density of 55 A/(cm/sup 2//spl middot/well) were achieved for a 25-/spl mu/m square etched mesa device at 80/spl deg/C.

Controlling polarization of vertical-cavity surface-emitting lasers using amorphous silicon subwavelength transmission gratings

Control of the polarization of vertical-cavity surface-emitting lasers (VCSELs) using a 240-nm-thick amorphous silicon subwavelength transmission grating (SWTG) is demonstrated. The grating, which has a strong polarization dependent reflectance and transmittance, was placed in front of the output window of a VCSEL. It was found that the SWTG can fix the VCSEL’s polarization in the direction perpendicular to the grating fingers, switch polarization directions, enhance the polarization ratio from 20:1 to over 200:1, and decrease the threshold current. Integration of these gratings into the VCSEL structure is discussed.