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12LS-I-8
Large-aperture quasi-phase-matching stacks of multiple GaAs plates fabricated with the room-temperature bonding for high-power wavelength conversion in mid-IR region
1Chuo University, Department of Electrical, Electronic, and Communication Engineering, Tokyo, Japan
GaAs is an attractive material for mid-infrared wavelength conversion owing to its high optical nonlinearity and transparency up to 17 |im. Since GaAs is optically isotropic, quasi-phase matching (QPM) is essential for highly efficient wavelength conversion. Although epitaxially grown GaAs QPM devices have been reported [1], it is difficult to fabricate thick devices for highpower wavelength conversion. On the other hand, diffusion bonded stacks of GaAs plates were reported as large-apertures QPM devices [2]. However, the high-temperature process degraded the crystal quality and the transmittance. In this work, we report on fabrication of large-aperture QPM stacks of multiple GaAs plates using the room-temperature bonding (RTB) and their wavelength-conversion properties.
The GaAs plates used for bonding were (111) plates with the size of 5.5 mm x 5.0 mm x 106 p,m, the thickness of which corresponds to the first-order QPM second-harmonic generation (SHG) period for the fundamental wavelength of 10.6 p,m. Two plates are set face to face in the vacuum chamber, and their surfaces are irradiated by Ar atom beams to be activated. Then the two plates are atomically bonded when they are touched and pressed, and another plate is supplied by the translation stage after the bonded plates are pulled up. We have succeeded in fabricating a 53 plate-stacked structure, the photograph of which is shown in Fig. 1. The whole thickness is about 5.6 mm.
We performed the SHG measurement using a CO2 laser as a fundamental light source. Figure 1 shows the dependence of the SH power on the fundamental power for the 53-stacked and the previously fabricated 9-stacked devices. The SH power from the 53-plate stack (open circles) was 29 times higher than that from the previously fabricated 9-plate stack (open squares) [3]. We expect to obtain higher conversion efficiency and higher output power by increasing the number of plates.
I. Shoji1
0 2 4 6 8 10 12 Fundamental Power (W) Fig. 1. SH power vs. fundamental power. Inset: 53-plate QPM GaAs stack.
References
[1] S. Koh, T. Kondo, M. Ebihara, T. Ishiwada, H. Sawada, H. Ichinose, I. Shoji, and R. Ito, "GaAs/Ge/GaAs sublattice reversal epitaxy on GaAs (100) and (111) substrates for nonlinear optical devices," Jpn. J. Appl. Phys. 38, L508 (1999).
[2] L. A. Gordon, G. L. Woods, R. C. Eckardt, R. K. Route, R. S. Feigelson, M. M. Fejer, and R. L. Byer, "Diffusion bonded stacked GaAs for quasiphase-matched second-harmonic generation of a carbon dioxide laser," Electron. Lett. 29, 1942 (1993).
[3] T. Kubota, H. Atarashi, and I. Shoji, "Fabrication of quasi-phase-matching stacks of GaAs plates using a new technique: room-temperature bonding," Opt. Mater. Express 7, 932 (2017).
