20–50 kHz mid-infrared OP-GaAs OPO

Polarization effects and fiber-laser-pumping of a 2-µm-pumped OP-GaAs OPO

“…With respect to the fiber laser output power, the corresponding slope efficiency was determined to 31% (see figure 11b). This low value compared to that achieved with Q-switched Ho:YAG laser pumping (56% at 20 kHz [17,18] is attributed to the lower beam quality of the slightly multimode fiber used as well as the to possible non-optimized superposition of the two pump beams. At 20 kHz the optical-to-optical efficiency is 11% with a pump threshold of ∼3.5 W. The temporal pulse shape of the fiber laser pump, OPO output and non-converted pump beams are shown on figure 11a for 5.3 W of pump power.…”

“…Then, HVPE (Hybrid Vapor Phase Epitaxy) is efficient in growing hundreds of µm thick high-quality layers that preserve the grating at high growth rates and finally, efficient demonstrations of harmonic generation [13], difference frequency generation, and optical parametric oscillation [11,[14][15][16] were performed. Particularly, ZGP and OP-GaAs OPO exhibited almost identical performance for similar pump scheme [17][18][19][20]. As OP-GaAs presents linear optical isotropy and high symmetry of the nonlinear susceptibility, interesting polarization behavior has already been theoretically studied and experimentally demonstrated [14,15,17,21,22], suggesting that OP-GaAs can be efficiently pumped by sources of various polarizations including unpolarized sources such as some fiber lasers.…”

“…Particularly, ZGP and OP-GaAs OPO exhibited almost identical performance for similar pump scheme [17][18][19][20]. As OP-GaAs presents linear optical isotropy and high symmetry of the nonlinear susceptibility, interesting polarization behavior has already been theoretically studied and experimentally demonstrated [14,15,17,21,22], suggesting that OP-GaAs can be efficiently pumped by sources of various polarizations including unpolarized sources such as some fiber lasers. Because of the 0.9 µm band gap of GaAs, it will be difficult to pump GaAs samples with high peak power lasers having wavelengths under 1.8 µm due to twophoton absorption (β=10-20 cm/GW).…”

OP-GaAs OPO pumped by 2μm Q-switched lasers: Tm;Ho:silica fiber laser and Ho:YAG laser

“…We previously demonstrated that performance obtained with OP-GaAs crystal pumped by a 2.09 µm Ho:YAG laser was comparable to that obtained with the well known ZnGeP 2 non linear crystal in a similar pump scheme [11]. Interesting OP-GaAs polarization behavior has already been theoretically studied and experimentally demonstrated [7,8,10,14,15] suggesting that this crystal can be efficiently pumped by sources of various polarizations including unpolarized sources such as some fiber lasers. Due to two-photon absorption (β=10-20 cm/GW) OP-GaAs OPO should be pumped with high peak power lasers having wavelengths longer than 1.8 µm.…”

“…Then, a near-equilibrium technique, the atmospheric-pressure hydride vapor-phase epitaxy (HVPE), allows depositing additional material onto the pre-orientated substrates with perfect conservation of initial template crystallographic inversion with growth rates up to 30 µm/h. 500 μm-thick OP-GaAs samples are produced by this technique and have already shown good performance in OPO cavities [10][11][12][13]. We previously demonstrated that performance obtained with OP-GaAs crystal pumped by a 2.09 µm Ho:YAG laser was comparable to that obtained with the well known ZnGeP 2 non linear crystal in a similar pump scheme [11].…”