Thermal Rollover around 460 mW Observation in Single-Lateral Mode 780 nm Laser Diodes with Window-Mirror Structure

Yagi, T.; Tashiro, Yoshihisa; Ohkura, Y.; Abe, Shinji; Nishiguchi, H.; Mitsui, Y.

doi:10.1143/jjap.42.2316

Cited by 7 publications

(2 citation statements)

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“…The two foremost causes of facet heating are optical absorption of the laser light near the facet and non-radiative recombination of electron-hole pairs at the surface states of the cleaved facet. Inserting a high bandgap, current blocking region at the facet can greatly reduce the optical absorption and facet current leakage 12,13 .…”

Section: Advances In Multimode Brightness: 808 Nm Emitters With High Threshold For Catastrophic Optical Damagementioning

confidence: 99%

Advances in high brightness semiconductor lasers

Lammert

Osowski

et al. 2006

SPIE Proceedings

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We review recent advances in high power semiconductor lasers including increased spectral brightness, increased spatial brightness, and reduced cost architectures at wavelengths from the near infrared to the eye-safe regime. Data are presented which demonstrate both edge emitter devices and high power surface emitting 2-dimensional arrays with internal gratings to narrow and stabilize the spectrum. Diodes with multimode high spatial brightness and high power single mode performance in the 808 and 976nm regime are described, and advances in high power bars at eye-safe wavelengths are presented. These devices have the potential to dramatically improve diode pumped systems and enable new direct diode applications.Keywords: Diode, laser, semiconductor, bar, stack, array IntroductionConventional edge emitting high power diode lasers have been used in printing, defense, medical, and materials processing because of their compactness, low cost per Watt-hour, and excellent electrical to optical efficiency. While these high power diode lasers are broadly accepted for low brightness applications, their use has been limited due to the low spatial and spectral brightness performance, costly power scaling, and limited range of emission wavelengths. In particular, the spatial beam quality from high power diode lasers is a factor of 10-20 times lower than non-diode lasers such as gas, solid state, or fiber laser counterparts. Moreover, the spectral output of conventional diode lasers is typically an order of magnitude wider than these non-diode systems and is inadequate for efficient wavelength conversion or other pumping applications requiring narrow linewidth. Power scaling is achieved by combining the output of individually mounted bars, the cost of which scales linearly or superlinearly with power. Finally, the range of wavelengths available commercially from high power conventional diode lasers has mainly been limited to broadband emission in the near infrared regime of 800 nm to 980 nm.

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Section: Advances In Multimode Brightness: 808 Nm Emitters With High Threshold For Catastrophic Optical Damagementioning

confidence: 99%

Advances in high brightness semiconductor lasers

Lammert

Osowski

et al. 2006

SPIE Proceedings

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“…[ 3 ] Other attractive qualities of ceramic gain media are the ability to produce them in large sizes, increased mechanical toughness, and the spatial tailorability of dopant distributions. The limits to power density in high power lasers are often due to thermal rollover [ 4 ] from thermal lensing and depolarization effects, while catastrophic failures can be caused by thermal stress fracture. [ 5 ] A higher thermal conductivity k of the lasing media reduces the peak temperature and thermal gradients in the lasing media, thus allowing higher lasing powers [ 6 ] important for both continuous wave (CW) and pulsed lasers with high repetition rates.…”

Section: Introductionmentioning

confidence: 99%

Leveraging Anisotropy for Coupled Optimization of Thermal Transport and Light Transmission in Micro‐Structured Materials for High‐Power Laser Applications

Mishra

Garay

Dames

2020

Advcd Theory and Sims

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Maximum operating power densities in ceramic laser media scale with thermal conductivity k. This requires larger grain sizes in polycrystalline ceramics to reduce phonon scattering at grain boundaries. However, smaller grain sizes are preferred to minimize light scattering in the Rayleigh regime in polycrystals made from birefringent materials such as AlN and Al2O3, which are otherwise appealing for their high k. An optimization challenge arises from the opposite scaling laws governing the effects of grain sizes on k and light transmission. Here, this is tackled by introducing anisotropically microstructured materials (columnar/disk‐shaped grains) as the lasing media, and allowing orthogonal heat transfer and lasing directions. For columnar grains, larger grain sizes along the c‐axis help maintain high k for good heat dissipation, while preserving light transmission properties in the orthogonal lasing and pumping directions. Analytical models for the thermal conductivity in such structures are presented and verified using Monte‐Carlo ray‐tracing simulations. Similarly, an approximate Rayleigh–Gans–Debye model is used to predict light transmission and verified with exact simulations using FEM software. Finally, the tradeoff between thermal and optical phenomena is captured in a new anisotropic figure‐of‐merit tensor, which is optimized for the microstructure that maximizes lasing media performance in AlN and Al2O3 model systems.

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