High-power conversion efficiency Al-free diode lasers for pumping high-power solid-state laser systems

Kanskar, M.; Earles, T.; Goodnough, T.J.; Stiers, E.; Botez, D.; Mawst, Luke J.

doi:10.1117/12.597097

Cited by 16 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When comparing standard laser-pumped-laser resonators utilizing diode-pumped laser crystals or glasses with diodepumped-laser resonators, one significant difference is apparent. Unlike crystalline laser materials, where losses per unit length are minimal, with diode lasers the modal absorption α 0 coefficient can be quite large, typically 5 cm -1 [10], although recently values of 1 cm -1 or less have been demonstrated [11] and even smaller values are expected in the future. In our treatment of laser-pumped-laser resonators in the aforementioned, we presented results for the case where α l = 0, a good approximation for laser-pumped-laser resonators but not for diode-laser-pumped resonators.…”

Section: Extraction Modelmentioning

confidence: 99%

Rigrod laser-pumped-laser resonator model: I. Theoretical considerations

Brown¹

2014

Laser Phys.

View full text Add to dashboard Cite

Dilute laser materials whose ion doping is minimized are attractive because Auger up-conversion is minimized, substantially lower heat fractions result and transverse or longitudinal gain and heat deposition gradients are reduced. In addition, amplified spontaneous emission (ASE) effects are minimized as well. Lasers using dilute laser materials, however, tend to have lowered efficiencies due to the difficulty in obtaining efficient absorption in laser crystals of reasonable length. This is primarily because of the use of simple single or double-passed pump absorption schemes. While this difficulty may be overcome using multi-passed absorption pump beams, as has been successfully demonstrated in connection with the development of thin-disc lasers, higher absorption and efficiency are obtained with added complexity and cost. In this paper, we present an alternative method in which a dilute or thin absorbing laser material is placed intra-cavity to a pump laser resonator. With the absorbing laser crystal acting as an effective outcoupler, we find that the highest absorption and resonator extraction efficiencies are obtained with the most dilute or thin materials when resonator mirrors of near unity reflectivity are used. This counter-intuitive result is explained by a corresponding long photon lifetime inside the laser resonator, which effectively multi-passes the absorbing laser crystal, leading to a very high absorption efficiency.

show abstract

Section: Extraction Modelmentioning

confidence: 99%

Rigrod laser-pumped-laser resonator model: I. Theoretical considerations

Brown¹

2014

Laser Phys.

View full text Add to dashboard Cite

show abstract

“…The wide emitter width makes it possible for broad-area lasers to achieve very high optical power operation unattainable from single-mode lasers simply by reducing optical power density at the front facet. Maximum CW optical output powers demonstrated from state-of-the-art broad-area lasers are ~20W [1][2][3][4][5]. However, the wide emitter width introduces unwanted characteristics in broad-area lasers including poor beam quality associated with beam filamentation.…”

Section: Introductionmentioning

confidence: 99%

Catastrophic facet and bulk degradation in high power multi-mode InGaAs strained quantum well single emitters

et al. 2009

View full text Add to dashboard Cite

Extensive investigations by a number of groups have identified catastrophic sudden degradation as the main failure mode in both single-mode and multi-mode InGaAs-AlGaAs strained quantum well (QW) lasers. Significant progress made in performance characteristics of broad-area InGaAs strained QW single emitters in recent years has led to an optical output power of over 20W and a power conversion efficiency of over 70% under CW operation. However, unlike 980nm single-mode lasers that have shown high reliability operation under a high optical power density of ~50MW/cm 2 , broad-area lasers have not achieved the same level of reliability even under a much lower optical power density of ~5MW/cm 2 . This paper investigates possible mechanisms that prevent broad-area lasers from achieving high reliability operation by performing accelerated lifetests of these devices and in-depth failure mode analyses of degraded devices with various destructive and non-destructive techniques including EBIC, FIB, and HR-TEM techniques. The diode lasers that we have investigated are commercial MOCVD-grown broad-area strained InGaAs single QW lasers at ~975nm. Both passivated and unpassivated broad-area lasers were studied that yielded catastrophic failures at the front facet and also in the bulk. To investigate the role that generation and propagation of defects plays in degradation processes via recombination enhanced defect reaction (REDR), EBIC was employed to study dark line defects in degraded lasers, failed under different stress conditions, and the correlation between DLDs and stress levels is reported. FIB was then employed to prepare TEM samples from the DLD areas for cross-sectional HR-TEM analysis.

show abstract

“…To enhance η c of a laser structure, the following factors need to be considered: (a) improving the internal quantum efficiency by increasing the electron injection efficiency and reducing the carrier leakage. (b) Optimizing the doping and material composition to reduce the series resistance [36]. Series resistance can be induced by many different material junctions, such as the metal-semiconductor contact and the semiconductor heterojunctions.…”

Section: Epitaxial Structure Design and Device Fabricationmentioning

confidence: 99%

808 nm broad-area laser diodes designed for high efficiency at high-temperature operation

Lan

Yang

Liu

et al. 2021

Semicond. Sci. Technol.

View full text Add to dashboard Cite

Semiconductor lasers with high power conversion efficiency (PCE) and output power are heavily investigated driven by more energy-efficient commercial applications. In this paper, an asymmetric broad area laser (A-BAL) design is studied and compared with a conventional symmetric broad area laser (S-BAL) design for 808 nm single emitter laser diodes. We present a comparative theoretical and experimental investigation by studying the thermal effects on the laser parameters. The output characteristics and efficiency loss paths for the designs were analyzed. The leakage of carriers was identified as the primary source of the PCE reduction with temperature. Suppressing this leakage by optimization of the A-BAL design, a record continuous-wave PCE of 68% at 25 • C and 60.4% at 75 • C were achieved for a single emitter laser with 10 W output power. These devices deliver high efficiency at high temperatures with reliable operation achieving 2000 h of an accelerated aging lifetime without failures.

show abstract

High-power conversion efficiency Al-free diode lasers for pumping high-power solid-state laser systems

Cited by 16 publications

References 0 publications

Rigrod laser-pumped-laser resonator model: I. Theoretical considerations

Rigrod laser-pumped-laser resonator model: I. Theoretical considerations

Catastrophic facet and bulk degradation in high power multi-mode InGaAs strained quantum well single emitters

808 nm broad-area laser diodes designed for high efficiency at high-temperature operation

Contact Info

Product

Resources

About