Marc Eichhorn

High-pulse-energy actively Q-switched Tm 3+ -doped silica 2 μm fiber laser pumped at 792 nm

A diode-pumped Q-switched Tm3+-doped double-clad silica fiber laser is reported providing average powers of up to 30 W at pulse widths of only 41 ns and repetition rates in the range of 10-125 kHz. Up to 270 μJ pulse energy was produced. Amplified spontaneous emission (ASE) buildup limits the maximum peak power, and the pump power and average output power at the point of ASE induced clamping were found to depend linearly on the repetition rate.

High-efficiency 20–50 kHz mid-infrared orientation-patterned GaAs optical parametric oscillator pumped by a 2 μm holmium laser

We report on what are, to our knowledge, the best results obtained with an orientation-patterned GaAs optical parametric oscillator (OPO) pumped by a Q-switched 2 microm Ho:YAG laser. Up to 2.85 W are obtained for 6.1 W of pump power, corresponding to an optical-to-optical conversion efficiency of 46.5% with a threshold of 1 W. Optical damage occurred at a fluence of about 2 J/cm2. The thickness of the crystal limited the pump power. Slope efficiencies are of the same order as those obtained with ZnGeP2 OPOs pumped with the same Ho:YAG laser.

Actively Q-switched and mode-locked Tm 3+-doped silicate 2 μm fiber laser for supercontinuum generation in fluoride fiber

A diode-pumped actively Q-switched and actively mode-locked Tm3+-doped double-clad silicate fiber laser is reported providing up to 5 W of average output power at ~60 kHz Q-switch envelope repetition rate and ~8 μJ subpulses with up to 2.4 kW peak power. Using this source as a pump laser for supercontinuum generation in a ZBLAN fiber, over 1080 mW of supercontinuum from 1.9 μm to beyond 3.6 μm was obtained at an overall efficiency of 3.3% with respect to the diode pump power.

High-pulse-energy, actively Q-switched Tm 3+ ,Ho 3+ -codoped silica 2μm fiber laser

A diode-pumped Q-switched Tm3+,Ho3+-codoped double-clad silica fiber laser is reported providing average powers of up to 12.3 W at 2072.7 nm and stable pulse widths of only 45 ns and repetition rates in the range 10-100 kHz. Instabilities in pulse shape occur at nonoptimum cavity alignment and were found to be linked to the mechanism responsible for self mode locking.

Q-switched resonantly diode-pumped Er3+:YAG laser with fiberlike geometry

Crystalline fiberlike diode-pumped laser systems offer a convenient way to obtain compact, robust, and efficient operation whenever long active media are required. One of these cases is the diode-pumped Er(3+):YAG laser emitting at 1.6 microm, where long crystals are needed to avoid the upconversion processes. By resonantly pumping the (4)I(13/2) level around 1.53 microm, and by confining the pump radiation into the crystal by total internal reflection, a maximum output power of 14.5 W in cw mode is reached when pumped with approximately 40 W of absorbed power. In Q-switching mode, pulse energies of more than 8 mJ were obtained at a repetition rate of 90 Hz, limited by coating damage.

High-power actively mode-locked sub-nanosecond Tm 3+ -doped silica fiber laser

A diode-pumped actively mode-locked Tm³⁺-doped double-clad silica fiber laser providing up to 11.8 W of average output power and pulse widths in mode-locked operation of 38 ps at a repetition rate of 37.88 MHz is reported. Pulse energies of up to 314 nJ were obtained.

Development of a high-pulse-energy Q-switched Tm-doped double-clad fluoride fiber laser and its application to the pumping of mid-IR lasers.

A diode-pumped Q-switched Tm-doped double-clad fluoride fiber laser is reported providing up to 90 microJ pulse energy (160 ns, 100 kHz, i.e., 9 W of average power). The dependence of the fiber lasers repetition rate on pump power and modulator repetition rate was investigated. By amplification even higher pulse energies of 410 microJ could be generated. In a second stage of the setup the Q-switched fiber laser serves as a pump for a gain-switched tunable Cr2+:ZnSe laser. The pulse energies reported are to the authors knowledge the highest generated by Tm-doped fluoride fiber lasers or amplifiers today.

Optical parametric generation in CdSiP 2 at 6.125 μm pumped by 8 ns long pulses at 1064 nm

A 21.4 mm long noncritically cut CdSiP2 crystal, pumped by 8 ns pulses at 1064 nm in a double-pass configuration for pump, signal, and idler, generated 523 μJ, 5.8 ns idler pulses at 6.125 μm. The average power of 52.3 mW at the repetition rate of 100 Hz is the highest ever achieved at such wavelengths with direct down conversion from the 1 μm spectral range.

High Power Supercontinuum Generation in Fluoride Fibers Pumped by 2

High power supercontinuum generation in fluoride step-index optical fibers pumped with 2- μm pulses delivered by a gain-switched thulium-doped fiber laser and amplifier system is reported. An output average power of 1.25 W in the ~ 1.8-4.15 μm spectral band and 1.82 W in the ~ 1.8-3.65 μm band was achieved for two fluorozirconate fibers of different parameters. The first demonstration of Watt-level supercontinuum generation in a fluoroindate fiber is also demonstrated. The achieved output SC powers are the highest ones ever reported for fluoride fibers pumped with 2- μm gain-switched optical pulses.

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A diode-pumped Tm-doped fiber-optic amplifier that has a small-signal gain of >30 dB at 1870 nm is reported. Output pulses of up to 3-W peak power at a 1-60-kHz repetition rate can be generated by amplification of 20-40-ns laser diode pulses of up to 2-mW launched peak power. The output signal quality, i.e., the ratio of the output pulse energy and the total amplified spontaneous emission (ASE) output energy between two pulses, depends on the relative propagation direction of pump and signal and can be dramatically increased by choice of the correct propagation scheme. In the optimum pump geometry the pulse energy can be raised to as much as 20 times the ASE energy. This is the first report to the authors knowledge of fiber-optic amplification of short diode laser pulses near 1.9 microm with high repetition rates in Tm-doped fibers.