16-µm infrared generation by difference-frequency mixing in diffusion-bonded-stacked GaAs

Abstract

Tunable 90-ps 15.6-17.6-microm coherent radiation was generated by means of difference-frequency mixing in diffusion-bonded-stacked GaAs. The sample consisted of 24 alternately rotated layers with a total length of 6 mm and with low optical loss to achieve third-order quasi-phase matching. The wavelength-tuning curve was close to the theoretical prediction, demonstrating that the bonding process maintained nonlinear optical phase matching over the entire interaction length. Maximum conversion efficiency of 0.7%, or 5% internal quantum efficiency, was measured at 16.6 microm, consistent with the theoretical predictions.

All-epitaxial fabrication of thick, orientation-patterned GaAs films for nonlinear optical frequency conversion

“…This QPM problem was solved first by the stack of plates approach 2 and made practical with the addition of wafer bonding. 3,4 This approach proved successful and capable of generating crystals of large aperture, but remains limited, as it is a serial fabrication process. In addition, fabricating very short period gratings by these techniques is extremely challenging.…”

Optical Parametric Generators and Amplifiers

“…Two-photon absorption is especially important for MIR devices which employ semiconductor crystals as gain media. For instance, AgGaS 2 , HgGa 2 S 4 should be pumped at wavelengths longer than 1.1 µm [68,69,79], for OP-GaAs, wavelengths above 1.55 µm should be used [51,80], while for ZnGeP 2 , pump wavelengths should be longer than 2 µm [71,81]. In oxide materials, including structured ferroelectrics, the fundamental bandgap is in the ultraviolet spectral region.…”

Wafer-fused orientation-patterned GaAs

“…Zinc-blende semiconductor compounds, such as GaAs, are excellent candidates for nonlinear optical frequency conversion in the infrared by QPM, if periodic crystal domain inversions are incorporated in those otherwise optically isotropic materials. The effective nonlinear optical coefficient of GaAs is higher than ferroelectric materials, such as periodically-polled LiNbO 3 . GaAs is also attractive for its high thermal conductivity, high laser damage threshold, and transparency from 0.8 µm to 17 µm and in the very far infrared to terahertz.…”

“…Second harmonic generation (SHG) in a QPM GaAs was first demonstrated using a 10.6 µm laser in 1976. 2 Wavelength conversion by difference frequency generation (DFG) in QPM GaAs and AlGaAs was also realized for long-wavelength infrared (LWIR) 3 and short-wavelength infrared (SWIR), 4 respectively. Most recently, Vodopyanov et al demonstrated room temperature terahertz generation in QPM GaAs using femtosecond laser pulses.…”

“…This freedom in choice of the orientation can be further explored for QPM and integrated device applications. [3][4][5][6][7][8]11 From the refractive index measurements for GaAs at 25°C, 12 the calculated relationships between idler and signal wavelengths (λ) across a range of QPM periods and for three pump wavelengths are shown in Fig. 1.…”