Wavelength-stabilized DBR high-power diode laser

Abstract

This paper reports a wavelength-stabilized high-power diode laser emitting up to 14 W CW in the 9xx nm range. Wavelength stabilization is achieved by a distributed Bragg reflector (DBR) monolithically integrated in the diode laser chip. Key features are identical layer epitaxy (ILE) and the use of a multiple-order electron beam lithography (EBL) optical confining grating. ILE avoids any regrowth or complex technology processes, while EBL multiple-order grating allows narrow-band back reflection and effective lateral optical confinement, and makes it possible to stabilize multiple wavelengths on the same wafer using a manufacturable and reliable technology. DBR diode lasers with different pitches, whose wavelengths were 3 nm spaced, were fabricated and high spectral purity (95% optical power within about 0.6 nm) and wavelength stability were measured. Moreover, the high uniformity of performances across the wafer with different emitted wavelengths demonstrates the maturity of the proposed technology for high-yield, high-volume laser diode production for wavelength-stabilized applications. A multi-emitter module, including ten DBR diode lasers, collimating and focusing optics, showed 100 W CW wavelength-stabilized output power at 14 A in a 135 μm core optical fiber within 0.17 NA. Single diode lasers, or multi-emitter modules, can be used to combine high-power optical beams by wavelength division multiplexing (WDM) using dichroic optics, scaling up beam power to the kW range and maintaining optical beam quality.

975 nm multimode semiconductor lasers with high-order Bragg diffraction gratings

“…This observation closely correlates with the calculated value of ΔT = 144 nm obtained from Eqs. (7) and (8). The clear confirmation of this agreement pro-vides further validation for the accuracy of our calculations and supports the reliability of our research.…”

“…The fabrication process of the low diffraction level DBR grating is relatively intricate due to their typical periods of a few hundred nanometers, although they do not incur diffraction losses. Electron beam lithography (EBL) is generally employed to accomplish these grating structures [8,9] . In contrast, the high-order DBR with a diffraction level N larger than 10 and periods exceeding 1 μm can be successfully fabricated utilizing conventional contact-mode ultraviolet exposure lithography, reducing manufacturing costs [10] .…”

Novel 1064 nm DBR lasers combining active layer removal and surface gratings

“…This creates deep level traps that promote nonradiative recombination and therefore degrade the laser performance. Therefore, state-of-the-art DBR lasers emitting in the spectral region between 600 and 1200 nm are distinguished by an active layer extending over the whole cavity including the grating section [3][4][5][6][7][8][9][10]. This is possible because, first, the inter-valence band absorption is small, second, the intra-band (free carrier) absorption can be kept small by an appropriate doping profile, and third, the inter-band absorption can be saturated by optically creating electron-hole pairs.…”