Advancements in VCSEL and edge emitter laser diode technology, associated micro-optics and drive electronics has enabled use of direct diode lasers as illumination sources for solid-state lidar. This paper will discuss advancements in integrated, low cost solid-state laser diode based illumination sources that offer pulse widths below 5ns and peak powers over 1kW with very small form factors. Data will be presented on state-of-the-art near-infrared (NIR) and short-wave infrared (SWIR) sources. The impact on beam size and shape upon adding micro-optics to the assembly will also be shown.
Maximizing brightness and peak power out of the laser diode array is essential in the development of high powered solid state and fiber laser systems. Recent developments have enabled single 1 cm laser diode bars capable of producing over 500W peak power at wavelengths between 770nm and 1100nm. New technologies in bar cooling and optical beam shaping have allowed scaled laser pump diodes to achieve peak powers over 1MW. Novel manifold designs have allowed 100kW to 1MW stacks maintaining a brightness of over 11kW/cm<sup>2</sup>. The latest performance from high brightness pump diodes operating under a variety of pulse conditions will be discussed. Additionally, discussion will be provided regarding a novel method of powering and controlling diodes with megawatt-class powers in MIL applications.
Enhancements of laser diode epitaxy in conjunction with process and packaging improvements have led to the availability of 1cm bars capable of over 500W peak power at near-infrared wavelengths (770nm to 1100nm). Advances in cooler design allow for multi-bar stacks with bar-to-bar pitches as low as 350μm and a scalable package architecture enabled a single diode assembly with total peak powers of over 1MegaWatt of peak power. With the addition of micro-optics, overall array brightness greater than 10kW/cm<sup>2 </sup>was achieved. Performance metrics of barbased diode lasers specifically engineered for high peak power and high brightness at wavelengths and pulse conditions commonly used to pump a variety of fiber and solid-state materials are presented.
Military, industrial, and medical applications have expressed interest in using ~1550nm laser diodes as efficient laser sources for reduced eye safety concerns, especially where free-space propagation is concerned. In addition, covert military applications, including pointers and illuminators, benefit from the spectral insensitivity of common sensor types to ~1.5um wavelengths. While more efficient than other sources, high-power broad-area laser diodes can sometimes require complex packaging and beam shaping/combining optics in order to meet requirements for brightness, uniformity, stray light, and environmental insensitivity. This paper will highlight and discuss a range of developments exploring laser diode components near 1.5um for free-space military applications, including broadarea high-power illuminators and highly-collimated pointers. Options for tailored beam conditioning and performance results will also be presented.
We report on the high-power high-temperature long-pulse performance of the 8XX-nm diode laser bars and arrays, which
were recently developed at Lasertel Inc. for diode laser pumping within high-temperature (130 °C) environment without
any cooling. Since certain energy in each pulse is required, the diode laser bars have to provide both high peak power
and a nice pulse shape at 130 °C. Optimizing the epi-structure of the diode laser, the laser cavity and the distribution of
waste heat, we demonstrate over 40-millisecond long-pulse operation of the 8XX-nm CS bars at 130 °C and 100 A.
Pumping the bar with 5-Hz frequency 15-millisecond rectangular current pulses, we generate over 60 W peak power at
100 A and 130 °C. During the pulse duration, the pulse shape of the CS bars is well-maintained and the power almost
linearly decays with a rate of 1.9% peak power per millisecond at 130 °C and 100 A. Regardless of the pulse shape, this
laser bar can lase at very high temperature and output pulse can last for 8 ms/2ms at 170 °C/180 °C (both driven by 60 A
current pulses with 5-Hz frequency, 10 millisecond pulse width), respectively. To the best of our knowledge, this is the
highest operating temperature for a long-pulse 8XX-nm laser bar. Under the condition of 130 °C and 100 A, the laser bars
do not show any degradation after 310,000 10-millisecond current pulse shots. The performance of stack arrays at 130 °C
and 100 A are also presented. The development of reliable high-temperature diode laser bar paves the way for diode
laser long-pulse pumping within a high-temperature environment without any cooling.
This paper gives an overview of recent development of high-efficiency 50-W CW TE/TM polarized 808-nm diode laser
bar at Lasertel. Focused development of device design and MBE growth processes has yielded significant improvement
in power conversion efficiency (PCE) of 50-W CW TE/TM polarized 808-nm laser bars. We have achieved CW PCEs of
67 % to 64 % at heat-sink temperature of 5 °C and 25 °C, respectively. Ongoing life-testing indicates that the reliable
powers of devices based on the new developments exceed those of established, highly reliable, production designs.