Due to a wide transparency range (0.9-17 μm), a low absorption loss (~ 0.01 cm-1), and a laser damage threshold
comparable to ZGP crystals (~ 2 J/cm2), combined with excellent nonlinear, thermal and mechanical properties,
quasi-phase-matched orientation-patterned gallium arsenide (OP-GaAs) crystals are well adapted for efficient
mid-infrared optical parametric oscillators (OPOs).
The paper discusses the best results obtained, to our knowledge, with an OP-GaAs OPO pumped by a Qswitched
2.09 μm Ho3+:YAG laser. The compact (33 × 48 cm) high-repetition rate source developed allows to
achieve 4.0 W of average output power in the 3-5 μm range at 40 kHz repetition rate with a 45 % slope
efficiency and a very good beam quality (M2 < 1.8). 6.4 W were obtained at 70 kHz with a 51 % slope
efficiency, and 7.7 W at 100 kHz with a 46 % slope efficiency. At 40 kHz and 70 kHz, an optical damage
occurred at a fluence of 1.9 J/cm2 and 1.5 J/cm2 respectively. The power is limited by the OP-GaAs crystal
thickness and is expected to be scaled in thicker samples recently fabricated.
Improvement in hybrid vapour phase epitaxy growing techniques of quasi-phase-matched orientation-patterned GaAs
(OP-GaAs) allows larger sample thickness and permits efficient operation as a mid-infrared optical parametric oscillator
at Watt-level average output powers [1-3]. Especially its low absorption loss (- 0.01 cm-1), its laser damage threshold
comparable to ZGP (- 2 J/cm2) combined with a large nonlinear coefficient, a good thermal conductivity, excellent
mechanical properties, and a wide transparency range (0.9-17 μm) are suitable properties for efficient non-critical phase
matched OPOs. As there is no natural birefringence in GaAs, phase matching is independent of polarization and
propagation direction, offering the ability to pump OP-GaAs with a variety of polarization states. Thus, even unpolarized
or poorly polarized sources like simple fiber lasers have been efficiently used as pump sources [4-5].
The paper discuss the best OP-GaAs OPO results achieved, to our knowledge, using a Q-switched 2.09 μm Ho:YAG
laser as pump source as well as results obtained with an OP-GaAs OPO directly pumped by a 2.09 μm Q-switched
Tm,Ho:silica fiber laser. With a 2.09 μm Q-switched Ho:YAG fiber laser pump source up to 2.9 W of average output
power was achieved at 20 kHz repetition rate, 3.9 W at 40 kHz and 4.9 W at 50 kHz. With a 2.09 μm Q-switched
Tm3+,Ho3+:silica fiber laser pump source, up to 2.2 W of average output power was achieved at 40 kHz repetition rate,
1.9 W at 60 kHz and 1.3 W at 75 kHz in the mid-infrared range.
Gallium arsenide combines a large nonlinear coefficient, a good thermal conductivity, excellent mechanical properties,
and a wide transparency range (0.9-17μm). Improvement in hybrid vapour phase epitaxy growing techniques of quasiphase-
matched orientation-patterned GaAs (OP-GaAs) allows larger sample thickness and permits efficient operation as
a mid-infrared optical parametric oscillator at Watt-level average output powers.
Especially its low absorption loss (~; 0.01 cm-1), its laser damage threshold comparable to ZGP (~ 2 J/cm2) are suitable
properties for efficient non-critical phase matched OPOs.
As there is no natural birefringence in GaAs, phase matching is independent of polarization and propagation direction,
offering the ability to pump OP-GaAs with a variety of polarization states. Thus, even unpolarized or poorly polarized
sources like simple fiber lasers have been efficiently used as pump sources.
The paper will discuss recent results obtained with an OP-GaAs OPO directly pumped by a 2.09 μm Q-switched
Tm,Ho:silica fiber laser and a study on polarization effects using a Q-switched 2.09 μm Ho:YAG laser as the pump.
With a 2.09 μm Q-switched Tm,Ho:silica fiber laser pump source, up to 2.2 W of average output power was achieved at
40 kHz repetition rate, 1.9 W at 60 kHz and 1.3 W at 75 kHz in the mid-infrared range.
Nonlinear optical materials play a key role in the development of coherent sources of radiation as they permit the
frequency conversion of mature solid-state lasers into spectral ranges where lasers do not exist or perform poorly. The
availability of efficient quasi-phasematched infrared materials is thus considered as important for the development of
several optronics applications.
This paper will review the recent progresses achieved with thick Orientation-Patterned GaAs structures. We will present
results obtained in growing a 500 μm thick layer on 2 cm long structures with low optical losses (less than 0.02 cm-1).
This loss coefficient is low enough to allow the operation of a highly efficient GaAs OPO in the Mid-IR range.
Nonlinear optical materials play a key role in the development of coherent sources of radiation as they permit the
frequency conversion of mature solid-state lasers into spectral ranges where lasers do not exist or perform poorly. The
availability of efficient quasi-phasematched infrared materials is thus considered as important for the development of
several defense optronics applications.
This paper will review the recent progresses we achieved with thick Orientation Patterned-GaAs structures. We will
present results obtained in growing thick-layer (500 µm) on 2 cm long structures with very low optical losses (less than
0.02 cm-1). This loss coefficient is low enough to allow the realization of a high power OPO in the MIR band.
Nonlinear optical materials play a key role in the development of coherent sources of radiation as they permit the frequency conversion of mature solid-state lasers into spectral ranges where lasers do not exist or perform poorly. The availability of efficient Quasi-Phase-Matched infrared materials is thus considered as important for the development of several defense optronics applications. This paper will review the progress we achieved so far with periodically oriented Gallium Arsenide.
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