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We develop a highly efficient quasi-phase-matched adhered ridge waveguide (QPM-ARW) in LiNbO _3 as a nonlinear material, and demonstrate tunable wavelength conversion without spectral inversion (SI) and parametric tunable dispersion compensation for a single-mode fiber (SMF) link. The QPM-ARW module with a second harmonic generation efficiency of 700 %/W achieves tunable wavelength conversion with a wavelength-tuning range of at least 25 nm through cascaded sum- and difference-frequency generation (SFG-DFG) process in which the signal and pumps are located symmetrically around the phase matching wavelength. The power penalty of the wavelength conversion is less than 0.6 dB for 43-Gb/s nonreturn-to-zero on–off-keying (NRZ-OOK) signals. We then apply the tunable wavelength conversion without SI to the parametric tunable dispersion compensation scheme, and achieve successful optical tunable dispersion compensation in 43-Gb/s NRZ-OOK transmissions over 53.2-km SMF. [ABSTRACT FROM PUBLISHER]

Second harmonic generation interference tomography which enables us to obtain three-dimensional images of ferroelectric antiparallel domain structures is devised. Periodically poled domains (PPDs) inside a LiTaO3 quasiphase matching crystal (QPM) are observed by this microscope. Section images perpendicular to the polar z axis show that the PPD structure is maintained throughout the top quarter of the sample but it starts to lose the periodic nature in the bottom half of the sample. Corresponding degradation of the QPM performance is observed along the z direction of the sample. [ABSTRACT FROM AUTHOR]

Uniform periodically poled domains were demonstrated in an insulator-sandwiched structure with z-cut lithium niobate wafers for an adhered ridge waveguide. Efficient quasi-phase-matched second harmonic generation was achieved in a mechanically defined ridge waveguide. Strong confinement in the waveguide produced second-harmonic-generation normalized conversion efficiency of 370%/W cm2 in the 1.5 μm wavelength region. [ABSTRACT FROM AUTHOR]

Uniform periodically poled domains were demonstrated in an insulator-sandwiched structure with z-cut lithium niobate wafers for an adhered ridge waveguide. Efficient quasi-phase-matched second harmonic generation was achieved in a mechanically defined ridge waveguide. Strong confinement in the waveguide produced second-harmonic-generation normalized conversion efficiency of 370%/W cm2 in the 1.5 μm wavelength region. [ABSTRACT FROM AUTHOR]

A low-threshold, nanosecond, optical parametric generator (OPG) was produced by using a 70-mm-long, periodically poled, Mg-doped, stoichiometric LiNbO3 (PPMgSLN). The periodically poled structure was obtained by applying an electric field of 1.8 kV/mm, which is lower than the coercive field of 3.9 kV/mm. The PPMgSLN OPG pumped with a 6 ns, 6.8 kHz, Nd:YAG microchip laser had a generation threshold of 12 MW/cm2 and a slope efficiency of 37% of signal at 1.61 μm. [ABSTRACT FROM AUTHOR]

Effective optical parametric oscillation (OPO) at room temperature was demonstrated by a periodically poled 1.0 mol% MgO-doped stoichiometric lithium tantalate (Mg:SLT) crystal. The slope conversion efficiency of total output power was ∼65% and the maximum output power was 655 mW at 1.3 W pumping without photorefraction. The difference of the OPO performance was investigated between 0.5 and 1.0 mol % Mg:SLT crystals, and a 1.0 mol % MgO-doped device exhibited better OPO performance and high resistance of photorefraction. The effective nonlinear coefficient of deff was found to be 10 pm/V by single-pass first-order quasiphase matched second-harmonic generation at 1064 nm. [ABSTRACT FROM AUTHOR]

Effective optical parametric oscillation (OPO) at room temperature was demonstrated by a periodically poled 1.0 mol% MgO-doped stoichiometric lithium tantalate (Mg:SLT) crystal. The slope conversion efficiency of total output power was ∼65% and the maximum output power was 655 mW at 1.3 W pumping without photorefraction. The difference of the OPO performance was investigated between 0.5 and 1.0 mol % Mg:SLT crystals, and a 1.0 mol % MgO-doped device exhibited better OPO performance and high resistance of photorefraction. The effective nonlinear coefficient of deff was found to be 10 pm/V by single-pass first-order quasiphase matched second-harmonic generation at 1064 nm. [ABSTRACT FROM AUTHOR]

Titanium-doped near-stoichiometric LiNbO3 (SLN) crystals were grown from lithium-rich solutions with a Ti concentration of up to approximately 20 mol% by a top-seeded solution-growth (TSSG) method. Ti-doped SLN (Ti:SLN) crystals with a Ti concentration of up to 9 mol% were free from inclusions, voids, cracks, or mechanical twins. The effective distribution coefficient keff for Ti in the Ti:SLN crystals was found to be approximately 0.45±0.05 for the Nb atom in the above composition range. The Ti-doping effects on Curie temperature, UV absorption edge, changes in the ordinary and extraordinary refractive indexes (Δno and Δne), and lattice constants were investigated. The Curie temperature for the Ti:SLN crystals linearly decreased with increasing Ti concentration up to 9 mol%. Both Δno and Δne linearly increased with increasing Ti concentration up to 9 mol%, and Δne was much larger than Δno over the entire wavelength range from 440 to 1550 nm. The UV absorption edge for the Ti:SLN crystals shifted to longer wavelengths with increasing Ti concentration. The a- and c-axes lattice constants in the Ti:SLN crystals decreased with increasing Ti concentration. In addition, a photoelastic effect on the refractive-index changes in the Ti:SLN crystal was estimated from the lattice-constant data. [Copyright &y& Elsevier]