Dominic F. Siriani

Implant Defined Anti-Guided Vertical-Cavity Surface-Emitting Laser Arrays

Anti-guided vertical-cavity surface-emitting laser (VCSEL) arrays can be designed to consistently operate in-phase, i.e., with a narrow, on-axis peak in the far field. However, the fabrication of such arrays typically requires anisotropic etching and epitaxial regrowth steps. We have found that anti-guiding behavior can be realized in implant-defined VCSEL arrays. The primary advantage is that the laser arrays can be designed to operate in-phase without requiring any fabrication steps more complicated than those used for conventional implant VCSELs. We present our array structure, a theoretical treatment of the anti-guiding confinement, and experimental results showing the behavior characteristic of anti-guided arrays.

Mode Control in Photonic Crystal Vertical-Cavity Surface-Emitting Lasers and Coherent Arrays

We demonstrate transverse mode control in vertical-cavity surface-emitting lasers (VCSELs) and 2-D VCSEL arrays. By etching a periodic arrangement of circular holes into the top distributed Bragg reflector mirror, we are able to control the lasing modes through index and loss confinement. Theoretical modeling of these confinement effects are shown to be consistent with experimental measurements. Photonic crystal etched patterns and ion-implanted photonic lattices have been employed to fabricate coherently-coupled 2-D arrays. Control of the array supermodes from the out-of-phase and in-phase conditions is discussed. Designs of photonic crystal coherent VCSEL arrays for high-power emission and beam steering applications are described.

Electronically Controlled Two-Dimensional Steering of In-Phase Coherently Coupled Vertical-Cavity Laser Arrays

Photonic crystal vertical-cavity surface-emitting laser arrays can be designed to lase only in the in-phase array supermode. By electronically addressing the array elements independently, the relative phases between the emission from each element can be altered. The shift in relative phase results in the angular deflection of the central peak of the in-phase array supermode. We demonstrate highly controllable steering of a coherent laser beam produced by a 2 2 array of emitters.

Loss-Induced Confinement in Photonic Crystal Vertical-Cavity Surface-Emitting Lasers

Through calculations and comparison with experimental results, we verify that loss introduced by an etched photonic crystal in a vertical-cavity surface-emitting laser (VCSEL) contributes significantly to the transverse optical confinement and supported modes. The optical loss is examined theoretically using a simple waveguide model from the scalar Helmholtz equation. The modal loss of fabricated lasers is extracted from the observed spectral-mode splitting. The effect of modal loss on the slope efficiency and modal behavior is examined. The model is found to be consistent with experimental measurements, and provides a means of accurate design of single-mode photonic crystal VCSELs.

37-GHz Modulation via Resonance Tuning in Single-Mode Coherent Vertical-Cavity Laser Arrays

We show a significant improvement of modulation bandwidth from

Phase and coherence extraction from a phased vertical cavity laser array

2\times 1

Loss and Index Guiding in Single-Mode Proton-Implanted Holey Vertical-Cavity Surface-Emitting Lasers

photonic crystal vertical-cavity surface-emitting laser arrays. Control of injection bias conditions to array elements enables resonance tuning of each element with variation of the phase relation and coherence of the array, resulting in the ability to tailor the modulation response. A bandwidth of 37 GHz is obtained under highly single-mode coherent operation with narrow spectral width and increased output power while the laser array is biased at low current density. Lasers with such performance characteristics may greatly enhance high-rate data transfer in computer server, data center, and supercomputer applications with potentially long device lifetime.

High-Speed Beam Steering With Phased Vertical Cavity Laser Arrays

The relative coherence and phase are extracted from two-element, coherently coupled, vertical cavity surface emitting laser arrays. The array elements are defined optically by a photonic crystal pattern and electrically by ion implantation. We obtain the near and far fields experimentally under varying current injection. The Fraunhofer approximation is used to simulate propagation from the near to far field. The phase and coherence are extracted as fitting parameters to match the experimental and propagated far field patterns. The phase and coherence will aid in future array designs and in elucidating the phase-shifting mechanism.

Beam steering via resonance detuning in coherently coupled vertical cavity laser arrays

Wedge-shaped holes are fabricated in the top mirror of proton-implanted vertical-cavity surface-emitting lasers (VCSELs). A radially symmetric fill factor approach is used to calculate the resulting transverse index profile. To investigate both the index confinement provided by the etched pattern and its effect on optical loss, continuous-wave (CW) and pulsed experiments are performed. Under CW operation, we show proper wedge design leads to improved fundamental-mode output power, decreased threshold, and increased efficiency. We report a significant decrease in threshold under pulsed operation for the etched device compared to an unetched device, indicating a significant reduction in diffraction loss to the fundamental mode due to strong index guiding. Single-mode output is maintained over the entire operating range of the VCSEL due to increased loss for the higher order modes

Coherence of Leaky-Mode Vertical-Cavity Surface-Emitting Laser Arrays

We demonstrate electronic beam steering using phased vertical cavity laser arrays at record high speed (1.4·108 deg/s) and sensitivity to current (1.2 deg/100 μA). The relative phase and coherence between the array elements are extracted with a Fraunhoffer propagation method. The spatially resolved spectrum and beam steering dynamics are also analyzed. The thermo-optic effect is found to dominate the phase-shifting mechanism at lower speed steering, while the electronic variation in index dominates at higher speeds (≥10 MHz).