We present breakthrough performance from green and blue InGaN-based laser diodes fabricated on nonpolar/semipolar
substrates. High-power, high-efficiency, and long-lifetime continuous-wave laser operation is demonstrated using these
novel crystal orientations. For green wavelengths at 520 nm, we report on continuous wave single mode lasing with75
mW of output power and wall plug efficiencies over 2.3%. In the blue regime we describe single-mode lasers operating
with over 23% wall plug efficiency and with output powers greater than 750 mW. These InGaN-based direct-diode
lasers offer significant improvement in performance, size, weight, and cost over conventional gas and solid state lasers.
Furthermore, these devices exhibit robust operation over a broad temperature range, can be directly modulated and do
not contain harmful residual infrared radiation typical of second harmonic generation lasers. These characteristics are
salient considerations for such optical devices in battlefield and other security applications.
We present state-of-the-art performance from green and blue InGaN-based laser diodes fabricated on nonpolar/semipolar
substrates. Using these novel crystal orientations, we demonstrate high-power, high-efficiency, and long-lifetime
continuous-wave laser operation. For green wavelengths at 520 nm, we report on continuous wave single mode lasing
with over 65 mW of output power and wall plug efficiencies over 2%. In the blue regime we describe single-mode
lasers operating with over 23% wall-plug-efficiency and with output powers greater than 750 mW. To the best of the
author's knowledge, this efficiency represents the highest reported to date for a single-mode blue laser. These InGaNbased
devices offer dramatic improvement in performance, size, weight, and cost over conventional gas and solid state
lasers for use in defense, biomedicine, and consumer projection displays.
Manufacturers of Nd:YAG lasers continue to demand 808 nm pump sources that deliver ever lower operating costs (measured in $/kW-hour). Responding to this demand, Coherent has developed a new generation of high power, 808 nm laser bars. These lasers are most ideal for high power QCW applications, but also perform very well in CW pumping applications. The key to the improved power for QCW bars is increase in catastrophic optical damage (COD) threshold. Through a combination of advances in epitaxial structure design and coating technology after aging COD limit for new generation of bars has been increased by 40%. This allowed us to achieve reliable QCW operation at 270W of peak power. Life test results shows that lifetime of these bars at these conditions exceed 2e9 shots. We also developed similar structure optimized for CW operations. When mounted on micro-channel water cooled packages CW bars operate reliably at an output power of 150 W. Highest power conversion efficiency (PCE) for CW bars was more
then 55% with typical PCE value >50%.
Solid-state-laser and fiber laser pumping, reprographics, medical and materials processing applications require high power, high-brightness bars and fiber-coupled arrays. Conductively cooled laser diode bars allow customers to simplify system design and reduce operational size, weight, and costs. We present results on next generation high brightness, high reliability bars and fiber-coupled arrays at 790-830 nm, 940 nm and 980 nm wavelengths. By using novel epitaxial structures, we have demonstrated highly reliable 808 nm, 30% fill-factor conductively cooled bars operating at 60W CW mode, corresponding to a linear power density (LPD) of 20 mW/μm. At 25°C, the bars have shown greater than 50% wall-plug-efficiency (WPE) when operating at 60W. Our novel approach has also reduced the fast-axis divergence FWHM from 31° to less than 24°. These bars have a 50% brightness improvement compared to our standard products with this geometry. At 980nm, we have demonstrated greater than 100W CW from 20% fill-factor conductively cooled bars, corresponding to a LPD of 50 mW/µm. At 25°C, the WPE for 976nm bars consistently peaks above 65% and remains greater than 60% at 100W. We coupled the beam output from those high-brightness bars into fiber-array-packages (“FAPs”), and we also achieved high-brightness and high-efficiency FAPs. We demonstrated 60W from a 600µm core-diameter fiber-bundle with a high WPE of 55%, and a low numerical aperture of 0.115. The brightness of such FAPs is four times higher than our standard high-power 40W FAP products at Coherent. Ongoing life test data suggests an extrapolated lifetime greater than 10,000 hours at 80W CW operating-condition based on 30%FF conductively cooled bar geometry.
We present a technique for monolithic integration of vertical cavity lasers and detectors with refractive microlenses etched on the back side of the semiconductor substrate in a wafer-scale process. This integration provides collimated or focused laser beam sources for applications in free-space interconnections or for coupling to optical fibers, and it improves the collection efficiency of detectors.
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