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We report the theory and experiment for an amplitude modulator and wavelength converter based on an electrode-coated asymmetric-duty-cycle periodically poled lithium niobate (PPLN). In a 56%/44% domain-duty-cycle PPLN crystal, we modulated the amplitude of the 532-nm second-harmonic output and measured a normalized half-wave voltage of 1.1 V×d (μm)/leff (cm), where d is the separation of the electrodes and leff is the effective electrode length defined by the PPLN length multiplying the deviation of the domain-duty-cycle from the 50% value. A modulation depth of 85% was obtained in the linear modulation regime. We also derived a unified theory to describe the half-wave voltage for two types of PPLN-based amplitude modulators. [Copyright &y& Elsevier]

A novel organic nonlinear optical material 4-methoxy benzaldehyde-N-methyl-4-stilbazolium tosylate has been synthesized and good optical quality crystals were grown by slow cooling solution growth technique. Powder X-ray diffraction studies have been carried out and the lattice parameters were calculated. FTIR spectra were recorded to identify the various functional groups present in the crystal. NMR spectrum studies have also been done. The powder second harmonic generation studies were done with Kurtz powder technique and the results were compared with urea. [Copyright &y& Elsevier]

We report simultaneous second harmonic generation (SHG) of a 1.064 μm laser and amplitude modulation of the 532 nm signal in a monolithic periodically-poled lithium niobate (PPLN) by electrically controlling the relative phase between the fundamental and the SHG waves in a lithium-niobate dispersion section sandwiched between two 2 – cm PPLN sections. When applying an electric field to the 1 – cm dispersion section, we measured a half-wave voltage of 525 V with an electrode separation of 0.5 mm. [Copyright &y& Elsevier]