A multi-mode 9XXnm-wavelength laser diode was developed to optimize the divergence angle and reliable ex-facet power. Lasers diodes were assembled into a multi-emitter pump package that is fiber coupled via spatial and polarization multiplexing. The pump package has a 135μm diameter output fiber that leverages the same optical train and mechanical design qualified previously. Up to ~ 270W CW power at 22A is achieved at a case temperature ~ 30ºC. Power conversion efficiency is 60% (peak) that drops to 53% at 22A with little thermal roll over. Greater than 90% of the light is collected at < 0.12NA at 16A drive current that produces 3.0W/(mm-mr)2 radiance from the output fiber.
Incorporating monolithic distributed feedback (DFB) gratings into broad-area (BA) diode lasers results in ten times narrower spectral width and four-to-five times lower thermal shift in emission wavelength. We report on our progress to obtaining a high-power, high-efficiency DFB diode pump in the 1.4-1.6 μm wavelength range for use in industrial and military, eye-safe applications. Results for Fabry-Perot diode lasers emitting at 1530 nm are also discussed. We report on an index-guided, single-emitter design (0.15 x 0.01 cm2) capable of producing 2.5 W of continuous-wave output power at room-temperature with a peak power conversion efficiency of 50%.
We report on our progress to obtaining a 1540 nm SE-DFB laser with curved, second order grating capable of producing
extremely high peak power for eye-safe range finding applications. Higher peak power can be extracted from SE-DFB
lasers since the emission area is three orders of magnitude larger than for edge emitters. Ten-times narrower spectral
width and four-times lower thermal shift of emission wavelength allows for the use of narrower filters on the range
finder detector, providing a higher signal-to-noise ratio. Furthermore, a curved second-order diffraction grating in our
SE-DFB laser allows for a higher brightness source, which makes transmitter optics geometry more compact and
Surface-emitting distributed feedback (SE-DFB) diode lasers possess many advantages compared to edge emitters, in
terms of power, brightness and spectral characteristics. We have demonstrated 312 W and 68 W of peak power at 1-μs
pulse duration and 100-Hz repetition rate from single 97x nm SE-DFB laser chips with electrically-pumped stripe of
3.75 mm2 and 0.18 mm2 respectively, achieving a power density of 378 W/mm2. Under the same pulsing condition, we
have also demonstrated current-limited 206 W of peak power out of a 100 μm / 0.22 NA fiber with only two 2x1 chiplevel
SE-DFB laser arrays.
Over the past few decades, diode laser technology development has achieved remarkable improvement in power,
reliability and efficiency. Spectral brightness,
wavelength-stabilization and spatial brightness are becoming very
important for pumping of novel solid-state gain media and fiber lasers especially for efficient and power-hungry
industrial and military applications. We will discuss the benefits of using 975 nm narrow-band curved grating Surfaceemitting
Distributed Feedback lasers for pumping fiber lasers and thin disk lasers. SE-DFB lasers with less than 0.25 nm
emission bandwidth, 0.07nm/°C thermal wavelength drift with over 50% power conversion efficiency has been achieved
with a single emitter producing 73 W of CW power. Two-dimensional arrays of these lasers have been made for power
scaling to achieve 1kW of power with less than 1nm spectral bandwidth. We will discuss the results and key advantages
of using spectrally and spatially bright diodes for pumping fiber and thin disk lasers.