Narrow Vertical Divergence Research Articles

High Power Conversion Efficiency Narrow Divergence Angle Photonic Crystal Laser Diodes

9xx nm laser diodes (LDs) with aluminum component continuous gradient photonic band crystal (CCG-PBC) waveguide structure are designed and fabricated. The simulation results indicate that the CCG-PBC structure can significantly reduce the heterojunction barrier and carrier accumulation at the interface of the conventional PBC structure. We demonstrate that the LD with CCG-PBC structure can achieve a narrow vertical divergence angle of 16.2° at full width at half maximum, and the divergence angle changes with current not more than 0.5°. Meanwhile, the power conversion efficiency (PCE) of the narrow divergence angle LD can reach 66.7%, and the PCE at 20 W is still over 60%. After optimizing the coating reflectivity and cavity length of the CCG-PBC structure LD, the peak PCE and power are 71.5% and 17.2 W at 25 °C and 77.7% and 23.3 W at 0 °C, respectively, which are optimal results for any edge-emitting LD. Our device provides valuable guidance for researching high power and high efficiency narrow vertical divergence angle LDs.

Electrically injected supersymmetric semiconductor lasers with narrow vertical divergence angle.

Electrically injected supersymmetric (SUSY) semiconductor lasers are proposed and fabricated. Two successive SUSY transformations are applied to the main array arranged along the direction of epitaxial growth, which can remove the propagation constants of the fundamental mode and the leaky mode of the main array from the superpartner while keeping those of other high-order modes. The SUSY laser possesses an excellent mode discrimination and favors the lasing of the fundamental mode. The fabricated SUSY laser can emit light with a single-lobe vertical far-field pattern with the full width at half maximum of 16.87° under an injection current of 1.4 A.

Narrow vertical divergence 780 nm lasers with modulated refractive index of photonic crystal structure

Narrow vertical divergence lasers for the 780 nm wavelength based on step index photonic crystal (STIN PC) and graded index photonic crystal (GRIN PC) structure are investigated. The effects of GaAsP and InGaAlAs as quantum well materials on device performance are studied. The STIN PC structure realizes a low threshold current of 0.52 A and high output power of 4.75 W at 5 A, while the GRIN PC structure has lower resistance and vertical divergence angle of only 21°. The device performance of GaAsP as a quantum well material is overall better than that of InGaAlAs.

High Power and Narrow Vertical Divergence Laser Diodes With Photonic Crystal Structure

High power and narrow vertical divergence lasers for the 980 nm wavelength range based on the photonic crystal (PC) structure are investigated. The structure of the PC layers and the position of the quantum well (QW) are optimized through mode analysis, which to maximize the output power of the PC laser. A broad area (BA) laser with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$300~\mu $ </tex-math></inline-formula> m width and 4 mm cavity length yields 41.8 W output with far-field divergence angles of 16.5° in lateral and 16.8° in vertical at full width at half maximum (FWHM) under continuous-wave (CW) 48 A operating current at 5 °C.

Design and Analysis of Laser Diodes Based on the Longitudinal Photonic Band Crystal Concept for High Power and Narrow Vertical Divergence

High-power low-vertical-divergence laser diodes based on the longitudinal photonic band crystal (PBC) concept are investigated at a wavelength of 900 nm. The thicknesses of the layers in the longitudinal PBC waveguide are prudently optimized by mode analysis, and the lowest vertical far-field angle is found to be achieved by mode coupling. A self-consistent model is also utilized to study the device performances in detail, which shows excellent optical properties without obvious electronic performance degradation. In the experiment, continuous wave power up to 1 W/facet and vertical far-field angles of less than 10° (full-width at half-maximum) and ~50° (with 95% power content) are achieved simultaneously, with epitaxial wafer containing PBC layers of ten periods. The agreement among the design, simulation, and experiment shows a bright prospect for further reduced vertical divergence angle with high power output.

1060-nm Ridge Waveguide Lasers Based on Extremely Wide Waveguides for 1.3-W Continuous-Wave Emission Into a Single Mode With FWHM Divergence Angle of $9^{\circ}\times 6^{\circ}$

Extremely large epitaxial waveguides with thickness t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">WG</sub> = 8.6 μm enable diode lasers with very narrow vertical divergence angle. We demonstrate that when such designs are processed in ridge waveguide laser format, there is substantial interaction between the vertical and lateral waveguiding mechanisms. For very narrow stripes with width w ≪ t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">WG</sub> , such interaction leads to lasing operation in the second-order mode in the vertical direction. For the case of an optimal stripe width w~t <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">WG</sub> single fundamental mode operation is achieved, with peak kink-free optical output power of 1.3 W and beam divergence angles (vertical, lateral) of 9° × 6° at full-width at half-maximum and 17° × 13° with 95% power content. The maximum brightness is 90 MW × cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> sr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> for 95% power content.