48 W Continuous-Wave Output From a High- Efficiency Single Emitter Laser Diode at 915 nm

Abstract

Improving the power and efficiency of 9xx-nm 1 broad-area laser diodes has a great help in reducing the cost 2 of laser systems and expanding applications. This letter presents 3 an optimized epitaxial structure with high power and conversion 4 efficiency. Laser diodes with 230 µm emitter width and 5 mm 5 cavity length deliver continuous-wave output power up to 48.5 W 6 at 48 A, 30 • C, the highest power reported for 9xx-nm single 7 emitter lasers so far. The slope efficiency is as high as 1.23 W/A 8 due to a low internal optical loss of 0.31 cm −1 and a high internal 9 efficiency of 96%. The maximum power conversion efficiency 10 reaches 72.6% at 15.3 W and 67.3% at the operating power of 11 30 W under a heatsink temperature of 25 • C. Life test results 12 show no failure in 1000 hours for 55 laser diodes. 13 Index Terms-Semiconductor laser, laser diode, high power, 14 high efficiency, 915 nm. 15 I. INTRODUCTION 16 H IGH power 9xx-nm laser diodes (LDs) are widely used 17 as pump sources for fiber lasers and light sources for 18 direct-diode systems in various industrial applications [1], [2], 19 [3], [4]. 915 nm pump LDs are the major choice for fiber 20 lasers because of their broad absorption band for Yb-doped 21 fibers [1], which has a big advantage for working conditions 22 in a large temperature range. A high-performance laser system 23 with an output power of 1-10 kW needs a large quantity 24 (100 to 1000) of pump LDs. The cost of these systems relies 25 dramatically on the LDs, which gives a stringent requirement 26 for the performance, quality, and reliability of the LD chips 27 [5], [6]. LDs with more than 30 W output power com-28 bined with power conversion efficiency (PCE) above 65% 29 can provide a cost-effective high-power laser module. The 30 output power is mainly limited by the catastrophic optical

48W continuous-wave output power with high efficiency from a single emitter laser diode at 915nm

“…The central wavelength increases from 904.4 nm at 5 A to 913.7 nm at 35 A with a calculated current drift coefficient of 0.31 nm/A. The FWHM of the spectra is broadened from 1.3 nm at 5 A to 3.6 nm at 35 A, resulting in a spectral broadening coefficient of 0.073 nm/A, possibly due to the thermal effects and carrier non-pinning [11]. The spectra are compatible with the broad absorption band of Yb-doped fibers in 915±10 nm.…”

“…Along with the rapid development of fiber lasers, high power and PCE have become more critical to provide a cost-effective laser diode. To increase the output power [9,10] and power conversion efficiency [11], epitaxial design methods [12][13][14][15], epitaxial growth technologies [16,17], facet reliability against COMD [18][19][20][21], and passivation technologies [8,22,23] have been greatly improved. Increasing the reliable output power and PCE are always fundamental pursuits in research and practical applications.…”

Epitaxially-Stacked High Efficiency Laser Diodes Near 905 nm

“…Optical cavities with very low internal optical loss should be employed for high slope efficiency. Low internal optical losses of 0.31 cm -1 for singlecavity LD [23] and 0.7 cm -1 for triple-cavity LD [18] were demonstrated. For the extensive use of edge-emitting LDs in LiDAR applications, utilizing a short laser cavity is desirable for a low cost.…”

Efficient power scaling of broad-area laser diodes from 915 to 1064 nm

“…The growing demand for high performance, cost-effectiveness, and reliability in large-scale applications has driven a pursuit for enhanced LD performance focusing on output power, power conversion efficiency (PCE), beam quality, and overall reliability. Previously, we demonstrated 48 W CW output from a single emitter LD at 915 nm, with maximum PCE reaching 72.6% [8,9]. Increasing the output power and PCE are everlasting goals in both research and practical applications.…”