Espen Lippert

Midinfrared laser source with high power and beam quality

A simple scheme for generation of high power in the midinfrared is demonstrated. By using a 15 W thulium-doped fiber laser emitting at 1907 nm to pump a Q-switched Ho:YAG laser, we obtained 9.8 W at 2096 nm at a 20 kHz pulse repetition rate with excellent beam quality. The output of this laser was used to pump a doubly resonant zinc germanium phosphide based optical parametric oscillator, and we obtained 5.1 W average power in the 3-5 microm range with M2 approximately = 1.8.

A 22-watt mid-infrared optical parametric oscillator with V-shaped 3-mirror ring resonator

We report on a ZnGeP(2)-based optical parametric oscillator (OPO) with 22 W of output power in the 3-5 µm range and a beam quality factor M(2) ≈1.4. The OPO uses a novel V-shaped 3-mirror ring resonator that allows two passes of the beams through the same nonlinear crystal. The pump is a 39 W hybrid Tm:fiber laser/Ho:YAG laser.

High power and efficient long wave IR ZnGeP2 parametric oscillator

A high power, efficient, and tunable laser source in the 8-10 microm range, based on a ZnGeP(2) optical parametric oscillator (OPO) pumped by a hybrid 2.1 microm laser is demonstrated. The hybrid laser consists of a Q-switched Ho:YAG laser pumped by a 15 W CW thulium fiber laser. With 8.9 W of 2.1 microm pump power we obtained 0.95 W at 8 microm with an M(2)-value of 2.7 from an OPO with two walk-off compensating crystals.

Mid-infrared source with 0.2 J pulse energy based on nonlinear conversion of Q-switched pulses in ZnGeP2.

Mid-infrared (3-5 μm) pulses with high energy are produced using nonlinear conversion in a ZnGeP(2)-based master oscillator-power amplifier, pumped by a Q-switched cryogenic Ho:YLF oscillator. The master oscillator is based on an optical parametric oscillator with a V-shaped 3-mirror ring resonator, and the power amplifier is based on optical parametric amplification in large-aperture ZnGeP(2) crystals. Pulses with up to 212 mJ energy at 1 Hz repetition rate are obtained, with FWHM duration 15 ns and beam quality M(2) = 3.

High-pulse-energy mid-infrared laser source based on optical parametric amplification in ZnGeP2

Nonlinear optical conversion of 1.064 µm pulses from a Q-switched Nd:YAG laser to the mid-infrared is demonstrated. The experimental setup is based on a two-stage master-oscillator/power-amplifier (MOPA) design with a KTiOPO4 based MOPA in the first stage and a KTiOAsO4/ZnGeP2 based MOPA in the second stage. The setup can be tuned to provide output at 8 µm or in the 3–5 µm wavelength region. We obtain more than 8 mJ at 8 µm, and up to 33 mJ at 3–5 µm. The measured beam quality factors are in the range M2=2–4 for both wavelength regions.

Efficient conversion from 1 to 2 µm by a KTP-based ring optical parametric oscillator

Conversion of Q -switched 1.064-microm Nd:YAG laser pulses to the 2-2.2-mu; m region with 46% efficiency is demonstrated with a KTP-based type 2 phase-matched optical parametric oscillator (OPO) with two pairs of walk-off compensating crystals in a ring resonator. With 10 mJ of pump energy, we obtain 2.5 mJ at the 2.06-microm signal and 2.1 mJ at the 2.2-microm idler, with a beam quality of M(2) approximately 1.4 . With a ZnGeP(2) -based OPO pumped by the signal from the KTP OPO we achieved 14% conversion efficiency from 1.064microm to the 3-5-microm range.

Mid-infrared optical parametric oscillator synchronously pumped by an erbium-doped fiber laser

A mid-infrared synchronously pumped optical parametric oscillator pumped by a femtosecond erbium-doped fiber laser is demonstrated and characterised. The idler is tunable from 3.7-4.7 μm, with a maximum average power of 37 mW and a pulse length of ∼ 480 fs at 4 μm. We compare the experimental results with numerical results based on an extensive simulation model.

Fiber laser pumped Mid-IR source

We report on a compact and efficient 3-5 μm laser source, based on a 1.9 μm Tm:fiber laser, pumping a Q-switched 2.1 μm Ho:YAG-laser, which in turn pumps a ZnGeP2 (ZGP) optical parametric oscillator (OPO). Recent advances in Tm:fiber laser technology has resulted in practical high power 1.9 μm sources, which are ideal pump sources for high pulse rate Q-switched Ho:YAG lasers. Using a 15 W commercial Tm:fiber laser we obtained 5.6W average output power from the Ho:YAG laser and 3 W from the ZGP OPO.

High-power fiber-laser-pumped mid-infrared laser sources

We present an efficient, high-power mid-infrared laser source using a Thulium fiber laser as pump source. The CW fiber laser pumps a Q-switched Ho:YAG laser which in turn pumps a ZnGeP2-based OPO. We have built a semi-ruggedized version of the laser for countermeasure field trials, and using a 15 W fiber laser we obtained 5.2 W output power in the 3-5 μm band. We also present work on scaling up the power by using a 65 W fiber laser as the pump. Simulations and initial experiments suggest that the scaled-up version could produce more than 25 W in the mid-IR.

High power multi-wavelength infrared source

μWe report on a high-power semi-ruggedized laser source, which can deliver radiation in all infrared transmission bands from 2 to 10 μm. In the source a 70 W Tm-doped fiber laser pumps a Q-switched Ho:YAG laser, which produces 37 W of output power at 2.1 μm. The Ho-laser pumps two ZnGeP2 OPOs. The first generates a combined power of 14 W at 3.9 μm and 4.5 μm, and the second generates watt-level outputs at 2.8 μm and 8 μm. The OPOs have a novel V-shaped 3-mirror ring resonator design, which gives high efficiency and beam quality.