Diode laser modules based on arrays of single emitters offer a number of advantages over bar-based solutions including enhanced reliability, higher brightness, and lower cost per bright watt. This approach has enabled a rapid proliferation of commercially available high-brightness fiber-coupled diode laser modules. Incorporating ever-greater numbers of emitters within a single module offers a direct path for power scaling while simultaneously maintaining high brightness and minimizing overall cost. While reports of long lifetimes for single emitter diode laser technology are widespread, the complex relationship between the standalone chip reliability and package-induced failure modes, as well as the impact of built-in redundancy offered by multiple emitters, are not often discussed. In this work, we present our approach to the modeling of fiber-coupled laser systems based on single-emitter laser diodes.

Spectrally-narrowed semiconductor laser diodes utilizing external volume gratings can be used to improve TEM00 power scaling and power conversion efficiency in diode-pumped solid state and fiber lasers. This approach is particularly attractive for pumping the narrow upper laser level of Nd:YAG DPSS lasers at 885 nm and the 1532 nm absorption band of Er:YAG DPSS lasers. While it is often believed that the use of such external gratings to wavelength lock diode lasers lead to unavoidable losses in power and efficiency, nLIGHT's proprietary laser designs and external volume grating integration techniques have eliminated these losses in our wavelength-locked diode laser products, enabling a broad range of spectrally locked laser diodes for pumping DPSS as well as fiber laser systems.

We report on the performance of a 100 W, 105 mu m, 0.17 NA (filled) fiber-coupled module operating at 976 nm. Volume holographic (Bragg) gratings are used to stabilize the emission spectrum to a 0.2 nm linewidth and wavelength-temperature coefficient below 0.01nm/degrees C with virtually no penalty to the operating power or efficiency of the device. The typical fiber coupling efficiency for this design is >90%, enabling a rated operating efficiency of similar to 50%, the highest reported for a 100W/105 mu m-class diode pump module (wavelength stabilized or otherwise).

We report on the development of ultra-high brightness laser diode modules at nLIGHT Photonics. This paper demonstrates a laser diode module capable of coupling over 100W at 976 nm into a 105 μm, 0.15 NA fiber with fiber coupling efficiency greater than 85%. The high brightness module has an optical excitation under 0.13 NA, is virtually free of cladding modes, and has been wavelength stabilized with the use of volume holographic gratings for narrow-band operation. Utilizing nLIGHT's Pearl product architecture, these modules are based on hard soldered single emitters packaged into a compact and passively-cooled package. These modules are designed to be compatible with high power 7:1 fused fiber combiners, enabling over 500W power coupled into a 220 μm, 0.22 NA fiber. These modules address the need in the market for high brightness and wavelength stabilized diode lasers for pumping fiber lasers and solid-state laser systems.

We report on the development of a high brightness laser diode module capable of coupling over 100W of optical power into a 105 mu m 0.15 NA fiber at 976 nm. This module, based on nLIGHT's Pearl (TM) product architecture, utilizes hard soldered single emitters packaged into a compact and passively-cooled package. In this system each diode is individually collimated in the fast and slow axes and free-space coupled into a single fiber. The high brightness module has an optical excitation under 0.13 NA, is virtually free of cladding modes, and has an electrical to optical efficiency greater than 40%. Additionally, this module is compatible with high power 7:1 fused fiber combiners, and initial experiments demonstrated 500W coupled into a 220 mu m, 0.22 NA fiber. These modules address the need in the market for higher brightness diode lasers for pumping fiber lasers and direct material processing.