Murray K. Reed

High-power optically pumped semiconductor lasers

Optically pumped, external-cavity, surface emitting semiconductor lasers (also known as optically pumped semiconductor lasers, OPS lasers, and vertical external cavity surface emitting lasers, VECSELs) generate near-diffraction limited beams from low brightness diode-array pumps. We have demonstrated 30 W cw at 980 nm and 15 W cw at 488 nm in a single spatial mode from these emitters and believe they can be scaled to > 100 W. Potential applications we have explored for such devices include wavelength conversion, spectral and spatial brightness conversion.

Widely tunable femtosecond optical parametric amplifier at 250 kHz with a Ti:sapphire regenerative amplifier

A Ti:sapphire mode-locked regenerative amplifier system pumped with a single argon-ion laser produces 4-μJ, 170-fs pulse of 800-nm wavelength at a 250-kHz repetition rate. Part of this output is used to generate a high-beam-quality white-light continuum, while the rest is doubled to 400 nm and used to parametrically amplify visible components of this continuum to more than 100 nJ. Synchronized with the visible signal pulse tunable from 460 to 700 nm is an infrared idler pulse tunable from 2.4 to 0.9 μm.

Recent advances in optically pumped semiconductor lasers

Optically pumped semiconductor lasers offer significant advantages with respect to all traditional diode-pumped solid state lasers (including fiber lasers) in regards to wavelength flexibility, broad pump tolerance, efficient spectral and spatial brightness conversion and high power scaling. In this talk we will describe our recent progress in the lab and applying this technology to commercial systems. Results include diversified wavelengths from 460 to 570nm, power scaling to >60W of CW 532nm, and the launch of a low cost 5W CW visible source for forensic applications.

Blue and green optically pumped semiconductor lasers for display

We discuss a compact RGB source with ouput power of several watts per color consisting of a red (638 nm) diode and OPS lasers with blue (460 nm) and green (530) nm output. Suitability for display applications is shown by replacing the lamp of a standard Rear Projection TV.

Double Gires-Tournois interferometer negative-dispersion mirrors for use in tunable mode-locked lasers.

We report the implementation and operation of novel superhigh-reflectivity negative-dispersion dielectric mirrors for use in tunable ultrafast laser systems. The mirror structure is divided into two distinct regions: an underlying superhigh-reflectivity dielectric quarter-wavelength stack and an overlying negative-dispersion section consisting of only a few layers and forming simple multiple Gires-Tournois interferometers. The example that we present was designed for operation from 800 to 900 nm and has a near-constant group-delay dispersion of -40 fs(2) and a peak reflectivity greater than 99.99%. We show a comparison of the predicted and the measured mirror performance and application of these mirrors in a mode-locked Ti:sapphire laser tunable from 805 to 915 nm.

Tunable ultraviolet generation using a femtosecond 250 kHz Ti:sapphire regenerative amplifier

A mode-locked Ti:sapphire regenerative amplifier system pumped with a single argon ion laser produces /spl mu/J energy 100 femtosecond pulses of 800 nm wavelength at 250 kHz repetition rate. Pumping a Type II BaB/sub 2/O/sub 4/ (BBO) optical parametric amplifiers (OPA) with this output generates 500 nJ infrared pulses and continuous tuning from 1.1 /spl mu/m to beyond 2.5 /spl mu/m. Difference frequency generation of the signal idler output from this OPA source in AgGaS/sub 2/ produces 60 nJ mid infrared pulses and continuous tuning from 2.4 /spl mu/m to beyond 12 /spl mu/m.

All-solid-state generation of 100-kHz tunable mid-infrared 50-fs pulses in type I and type II AgGaS(2).

We report the operation of an all-solid-state system for the generation of tunable mid-infrared sub-50-fs pulses. A Ti:sapphire regenerative amplifier, pumped by 10 W of power from 532-nm, diode-pumped, frequency-doubled Nd:YVO(4) lasers, produced 4-muJ energy, sub-50-fs pulses at 800 nm with a 100-kHz repetition rate. This output was used to drive a beta-BaB(2)O(4) optical parametric amplifier followed by a difference-frequency generator based on a AgGaS(2) crystal. Continuous tuning of ultrafast pulses from 2.4m to longer than 12mum was obtained. A performance comparison of difference-frequency generation in type I and type II phase-matched AgGaS(2) is reported.

30-fs pulses tunable across the visible with a 100-kHz Ti:sapphire regenerative amplifier.

A 100-kHz mode-locked Ti:sapphire-seeded regenerative amplifier pumping an optical parametric amplifier generates femtosecond pulses tunable from 470 to 710 nm. This output was compressed with a pair of prisms to bandwidth-limited pulses of 80- to 40-fs duration and more than 150 nJ of energy. These tunable pulses were then bandwidth expanded through self-phase modulation in bulk material and further compressed to less than 30-fs duration.

Robust hard-solder packaging of conduction cooled laser diode bars

We present the reliability of high-power laser diodes utilizing hard solder (AuSn) on a conduction-cooled package (HCCP). We present results of 50 W hard-pulse operation at 8xx nm and demonstrate a reliability of MTTF > 27 khrs (90% CL), which is an order of magnitude improvement over traditional packaging. We also present results at 9xx nm with a reliability of MTTF >17 khrs (90% CL) at 75 W. We discuss finite element analysis (FEA) modeling and time dependent temperature measurements combined with experimental life-test data to quantify true hard-pulse operation. We also discuss FEA and measured stress profiles across laser bars comparing soft and hard solder packaging.

Power-scaling of optically pumped semiconductor lasers

Power-scaling of optically pumped semiconductor lasers (OPSLs) using a resonator with multiple OPS chips is demonstrated. With a 3-chip cavity and intra-cavity second harmonic generation, we obtain 55W of TEM00 mode output at 532 nm and 66 W in multi-transverse mode. In addition, we describe the design of a periodic dynamically stable resonator that allows scaling to more than 4 chips and demonstrate that the output power scales with the number of chips in the cavity.