Fabrication of Thick Periodically-poled Lithium Niobate Crystals by Standard Electric Field Poling and Direct Bonding

Abstract

We fabricated 1 mm-thick periodically-poled lithium niobate (PPLN) crystals by using a high-voltage amplifier for standard electric field poling combined with a voltage multiplier. Furthermore, two 1 mm-thick PPLNs were directly bonded to make a 2 mm-thick PPLN. The large aperture allowed broad angular tuning, and a broad spectral range of quasi-phase matched second-harmonic generation can be achieved in a single channel. High-power applications are also expected.

Angle-tuned second-harmonic generation in periodically-poled lithium niobate

“…For detuning in the XZ-plane, however, we fabricated a 2-mm-thick PPLN by direct-bonding of two 1-mm-thick PPLNs. First, we periodically poled 1-mm-thick congruent LiNbO 3 crystals (Crystal Technology) by the standard electric field poling technique with a QPM period of 18.5 µm, and then the two PPLNs were directly bonded in water to make a 2-mm-thick PPLN [6]. The quality of direct-bonding was confirmed by measuring the transmission loss [6] and microscopic images of the bonding interface as shown in Fig.…”

“…Angular tuning was conducted in the XY -and XZ-planes, respectively. For tuning in the XZ-plane, we fabricated a 2-mm-thick PPLN by direct-bonding of two 1-mm-thick PPLNs made of congruent LiNbO 3 [6]. A larger tuning range of SHG was obtained for the detuning in the XZ-plane, continuously shifting the QPM peak of the fundamental wavelength from 1524 to 1594 nm when we changed the detuning angle from 0 • (parallel to the X-axis as conventional QPM) to 23 • .…”

Room temperature direct bonding of LiNbO3crystal layers and its application to high-voltage optical sensing

“…The thin sheets are usually directly bonded to a different material or to another LiNbO 3 substrate. Moreover, direct bonding of periodically pole LiNbO 3 on another LiNbO 3 substrate has been used for quasi-phase-matched second harmonic generation [16][17].…”

Hysteresis-free high-temperature precise bimorph actuators produced by direct bonding of lithium niobate wafers

“…This technology is widely used in MEMS fabrication, optoelectronics, and obtaining heterogeneous wafer stacks. 19,20 It was shown recently that the direct wafer bonding allows to increase the aperture of the periodically poled LN 21 and to produce the buried waveguides. 22 The direct bonding process is based on chemical bonds appearing between two flat surfaces without using any intermediate layers.…”