We report the infrared operation of a bulk optical Bragg modulator based on electro-optically induced refractive index gratings in z-cut periodically poled lithium niobate. Efficiencies in the first order of 45% for 1064 nm e-polarized light and 30% for o-polarized light were achieved, with maximum on/off ratios of 15:1 and 9:1, respectively. Field-induced light scattering effects due to poling are observed at higher drive voltages and compromised device performance due to these scattering effects is predicted to limit long-wavelength operation of these devices. © 2002 American Institute of Physics. ͓DOI: 10.1063/1.1510964͔ Many successful technologies exist for laser modulators including acousto-optic and bulk electro-optic devices. However, recently another class of modulators, based on Bragg diffraction in periodically poled materials, has attracted attention. 1,2 Their advantages include lower drive voltages and faster response times than conventional types. These devices are an extension of early work on grating based electrooptic devices such as those by Hammer 3 and Barros, 4 but by making use of periodic poling they allow additional design freedom.Bragg grating devices based on periodically poled LiNbO 3 ͑PPLN͒ were first investigated by Yamada 1 and Gnewuch 2 using visible light at 633 nm, and again by Yamada 5 using violet-blue light at 407 nm. Impressive maximum first order diffraction efficiencies of around 75% were reported by both authors. Gnewuch et al. demonstrated a fivefold reduction in switching time compared to acoustooptic devices, and also that periodic poling suppresses acoustic modes excited via the piezoelectric effect by the electrode capacitance. 6 Yamada et al. demonstrated several different optical functions using electro-optically controlled PPLN, such as focussing, switching, and deflecting, and confirmed that these fundamental operations may be integrated on the same substrate. More recently, Yamada et al. presented results for Bragg gratings used as an optical switch with one input and six outputs, and as a wide band optical modulator for violet-blue light. 5 In this letter we present results on PPLN-based electrooptic Bragg modulators operating at 1064 nm, describe their fabrication, and discuss operating considerations for such devices. We present results of field induced scattering at higher drive voltages, an effect found to result from the periodicpoling process, and our initial investigation of reduced device efficiency at 1064 nm when compared to visible operation. Light redistribution into higher orders and in-plane scatter are measured, and compromised performance at longer wavelengths due to this scatter is predicted.A PPLN-based Bragg modulator device consists of an area of periodically domain inverted regions forming a grating of length, d, and of period, ⌳, with grating k-vector parallel to the x axis of the crystal, an arrangement illustrated in Fig. 1. The devices used in this experiment were fabricated from 500-m-thick z-cut lithium niobate purchased from Yamaju C...

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We report the fabrication of a 12-mum -thick periodically poled LiNbO(3) planar waveguide buried in LiTaO(3) by direct bonding of precision-polished surfaces. Frequency doubling of the 1064-nm output of a cw diode-pumped Nd:YAG laser was performed in a 5.5-mm-long device with a 6.50-mum -period grating at an elevated temperature of 174 degrees C. The resultant green second-harmonic output exhibited fundamental-spatial-mode characteristics at a 4.3%W(-1) conversion efficiency.

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Periodic poling of LiNbO3 to achieve quasi-phase matching for non-linear frequency conversion has generated a great deal of interest due to the fact that it allows the use of a large non-linear coefficient and eliminates walk-off effects. Combining such material with a waveguide geometry to increase average pump intensities is a promising route to the realisation of various compact non-linear devices based on harmonic1 or parametric2 generation. Here we present the first fabrication of a PPLN planar waveguide by direct bonding. This technique, which has previously been used to fabricate laser waveguides3, is based on the precision polishing of bulk material to waveguide dimensions. Hence the full non-linearity of the bulk PPLN should be maintained while offering versatility in the fabrication of exotic waveguide structures.