We report an electro-optically (EO) tunable multi-wavelength optical parametric oscillator (OPO) based on a nonperiodically poled lithium niobate. EO spectral tuning rates of 0.5-0.58 nm/(kV/mm) are obtained with this OPO in the telecom C-L bands.

We demonstrate an electro-optically switchable multi-wavelength optical parametric oscillator (OPO) based on an aperiodically poled Li^D3 (APPLN). The OPO can radiate at 1540nm, 1550nm, or both wavelengths simply by switching the voltage on the APPLN.

We report the first fast switchable multiwavelength optical parametric oscillator based on aperiodic optical superlattice technology. The constructed aperiodically poled lithium niobate (APPLN) integrates the functionalities of two quasi-phase-matching devices on a chip to work simultaneously as an electro-optic (EO) switchable notch-like filter and a multiline optical parametric downconverter. When such an APPLN is built in a 1064-nm-pumped optical resonator system, we achieve the oscillation of dual signals at 1540 and 1550 nm, for a single signal at 1540 nm, and a single signal at 1550 nm in the system when the 3-cm-long APPLN is driven by 0 V, 354 V, and 805 V, respectively. The switching among the three signal spectra is operationally simple and electro-optically fast. The electro-optically switched signals also feature enhanced power spectral density due to the unique EO gain-spectrum filtering mechanism employed in this work.

In this work, we present a systematic experimental study of surface electric field poling for creating periodically poled lithium niobate. We want to control the homogeneity and the duty cycle of the periodic structures as well as domain shape and size in general. The created domain patterns are analyzed by selective etching with subsequent scanning electron microscopy. We investigate theoretically and experimentally how the shape of electrodes influences the poling results. Furthermore, the influence of the temporal waveform and magnitude of the applied poling voltage pulse is studied. Our results enable to identify optimal experimental parameters for high-quality surface poling.

Lithium niobate (LN) is a favourable material for many applications, especially in integrated optics, due to its excellent electro-optic, acousto-optic, and nonlinear optic properties. One promising application of LN is second-harmonic generation (SHG). For enhancing the efficiency of SHG, phase matching between the interacting waves is needed, which is often realized by employing quasi-phase matching (QPM) [1]. QPM is typically realized by periodic poling of LN [2,3], i.e. the periodic flipping of the crystal orientation. The needed period is determined by the wavelengths as well as by the wave vectors of the fundamental- and the second-harmonic waves (FW and SH, respectively). For the case of backward SHG with a fundamental wavelength of 1.55 μm, where the SH wave travels in the opposite direction to the FW, typically sub-micrometer periods of the poled LN are required [4].

Lithium niobate (LN) is widely used and established in nonlinear and integrated optics. Efficient nonlinear frequency conversion is enabled by quasi-phase matching of the interacting waves through periodic poling of the crystal domains. For realizing miniaturized optical devices, the application of lithium niobate on insulator (LNOI) substrates becomes increasingly important. LNOI consists of a LN thin film on top of a silica layer [1]. Using the common electric field poling [2] through an LNOI wafer is impeded by the insulating silica layer. Therefore, only surface poling techniques can be employed [3-5]. Here, the electric field is applied parallel to the substrate surface along the in-plane z-axis of the x-cut LN film. In this work, we present a systematic study of the surface domain engineering of bulk LN and LNOI, aiming to optimize the quality of the domain patterns.

In this paper, we propose an early merge mode decision algorithm for HEVC inter prediction to reduce the computational complexity using early zero-block (ZB) detection. To improve the coding performance degradation introduced in the proposed algorithm, we also propose a new merge candidate decision scheme which suggests using decoder-derived merge candidates for merge mode decision, based upon both sum of absolute bidirectional prediction differences (SABPD) and template matching (TM) criteria. In the proposed scheme, only a 1-bit flag for merge index is required for transmission instead of prefix coded merge index. The experimental results reveal that the proposed algorithm outperforms the inter prediction proposed in HEVC in both coding performance and computational complexity. The results demonstrate that at low bit rates the proposed algorithm achieves average 1.6% BDBR reduction with 38% reduction of total encoding time, compared to the original HEVC inter prediction.

We report on self-suspended micro-resonators patterned in Z-cut lithium niobate on insulator substrates. The fabrication technique consists of two single steps, focused ion beam milling for the micro-and nano-structuring and subsequent SiO2 etching for the realization of thin self-suspended membranes. The fabrication process of a free-standing photonic crystal cavity and a suspended micro-disk is described and the linear and nonlinear optical properties of the micro-resonators are investigated at telecommunication wavelengths. The whispering gallery modes of the micro-disk are measured experimentally and compared to an analytical model. The fundamental transverse-electric polarized mode of the photonic crystal cavity is measured and compared to three dimensional finite difference time domain simulations. Second harmonic generation enhancement due to the field confinement in the cavity mode is demonstrated. These results are promising for the use of Z-cut lithium niobate self-suspended membranes as platforms for highly efficient miniaturized photonic devices for telecommunication applications. (C) 2015 Optical Society of America

We report a unique spectral narrowing and manipulation technique in an optical parametric oscillator (OPO) realized by an integrated periodically poled lithium niobate comprising an optical parametric gain medium sandwiched by two electro-optic polarization-mode converters (EO PMCs). We achieved a manipulation of the gain spectrum of the OPO via EO and/or temperature control of the EO PMCs, in which we obtained single to multiple signal spectral peaks from the OPO with a spectral width reduced by up to 10 times and peak intensity increased by up to 6 times in comparison with the original signal. Fast EO tuning of the narrowed signal spectral peak has also been demonstrated.

We report on an efficient intracavity sum-frequency generator in a dual-wavelength Nd:YVO4 laser optimized with monolithically cascaded PPLN electro-optic Q-switches. >480-W peak-power orange 593-nm light was obtained with this system at 4.8-W diode pump power.