29 April 2010 High-power pulsed 976-nm DFB laser diodes
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Proceedings Volume 7682, Photonic Microdevices/Microstructures for Sensing II; 76820T (2010); doi: 10.1117/12.849981
Event: SPIE Defense, Security, and Sensing, 2010, Orlando, Florida, United States
Abstract
Distributed feedback (DFB) laser diodes nowadays provide stable single mode emission for many different applications covering a wide wavelength range. The available output power is usually limited because of catastrophical optical mirror damage (COD) caused by the small facet area. For some applications such as trace gas detection output powers of several ten milliwatts are sufficiently high, other applications like distance measurement or sensing in harsh environments however require much higher output power levels. We present a process combining optimizations of the layer structure with a new lateral design of the ridge waveguide which is fully compatible with standard coating and passivation processes. By implementing a large optical cavity with the active layer positioned not in the middle of the waveguide layers but very close to the upper edge, the lasers' farfield angles can be drastically reduced. Furthermore, the travelling light mode can be pushed down into the large optical cavity by continuously decreasing the ridge waveguide width towards both laser facets. The light mode then spreads over a much larger area, thus reducing the surface power density which leads to significantly higher COD thresholds. Laterally coupled DFB lasers based on this concept emitting at wavelengths around 976 nm yield hitherto unachievable COD thresholds of 1.6 W under pulsed operation. The high mode stability during the 50 ns pulses means such lasers are ideally suited for high precision distance measurement or similar tasks.
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Wolfgang Zeller, Martin Kamp, Johannes Koeth, Lukas Worschech, "High-power pulsed 976-nm DFB laser diodes", Proc. SPIE 7682, Photonic Microdevices/Microstructures for Sensing II, 76820T (29 April 2010); doi: 10.1117/12.849981; http://dx.doi.org/10.1117/12.849981
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KEYWORDS
Semiconductor lasers

Lab on a chip

Waveguides

Pulsed laser operation

Laser damage threshold

Optical resonators

Etching

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