We report on electro-optic beam deflection using an annealed proton exchange waveguide in lithium niobate (LN) with microstructured serrated array electrodes. Due to the electro-optic effect of the LN material, the experimental results show that the beam deflection and modulation of the LN waveguide can be realized with relatively low voltages. The total length of the serrated prism array electrodes structure is $\sim 5\mathrm{mm}$. With 20 V applied to the electrodes of 50, 100, and 150 μm wide waveguides, $\sim 1.28$, $\sim 0.96$, and $\sim 0.64\mathrm{\mu m}$ beam deflections were obtained, respectively, which are in accordance with theoretical simulation. This configuration can be potentially applied in optical beam scanning, high-speed switches, and optical beam smoothing technology.

A high-efficiency broadband orange laser is demonstrated by use of double-pass sum-frequency mixing in a step-chirped MgO-doped periodically poled lithium niobate (MgO:PPLN) crystal (ᴧ = 10.1-10.4 µm). The temperature-gradient technique is used to enhance the bandwidth of the output spectrum. A maximum orange output power of 129 mW (~65% conversion efficiency) was achieved at room temperature operation, and up to ~7.2 nm bandwidth at a temperature difference of 20 ᵒC was realized. This scheme presents an attractive approach for the generation of high power and broadband short-wavelength lasers from a single crystal, which may extend the potential biomedical and spectroscopic applications.

Integrated photonic devices are essential for on-chip optical communication, optical-electronic systems, and quantum information sciences. To develop a high-fidelity interface between photonics in various frequency domains without disturbing their quantum properties, nonlinear frequency conversion, typically steered with the quadratic (χ2) process, should be considered. Furthermore, another degree of freedom in steering the spatial modes during the χ2 process, with unprecedent mode intensity is proposed here by modulating the lithium niobate (LN) waveguide-based inter-mode quasi-phase-matching conditions with both temperature and wavelength parameters. Under high incident light intensities (25 and 27.8 dBm for the pump and the signal lights, respectively), mode conversion at the sum-frequency wavelength with sufficient high output power (−7 – 8 dBm) among the TM₀₁, TM₁₀, and TM₀₀ modes is realized automatically with characterized broad temperature (ΔT ≥ 8 °C) and wavelength windows (Δλ ≥ 1 nm), avoiding the previous efforts in carefully preparing the signal or pump modes. The results prove that high-intensity spatial modes can be prepared at arbitrary transparent wavelength of the χ2 media toward on-chip integration, which facilitates the development of chip-based communication and quantum information systems because spatial correlations can be applied to generate hyperentangled states and provide additional robustness in quantum error correction with the extended Hilbert space.

In this study, simultaneous second-harmonic generation (SHG), sum frequency generation (SFG), and Raman conversion based on MgO-doped periodically poled lithium niobate (MgO:PPLN) for multi-wavelength generation is demonstrated. The approach used is based on a single MgO:PPLN crystal poled with a uniform period of 10.2 µm that phase matches SHG and SFG, simultaneously. Using a simplified double-pass geometry, up to 0.8 W of blue light at 487 nm is achieved by a frequency-doubling 974 nm laser diode pump, and 0.5 W of orange light at 598 nm is generated by frequency mixing 974 nm pump with C-band (1527–1565 nm) tunable laser source. At high pump powers of the 974 nm laser source, other unexpected peaks at 437, 536, 756, 815 and 1038 nm were observed, of which the 1038 nm line is due to Stimulated Raman Scattering within the MgO:PPLN crystal. The resulting multi-wavelength light source may find a wide range of applications in biomedicine and basic research.

We have demonstrated sum-frequency generation of a compact continuous-wave orange laser in a step-chirped magnesium oxide doped periodically poled lithium niobate in single-pass mode. A 974 nm laser diode was mixed with a C-band amplified spontaneous emission laser source to yield a triple-wavelength operation at 594.9, 596.9, and 598.6 nm with a maximum output power of 9.3 mW and broad bandwidth of ~4.4 nm. The triple-wavelength output power stability was ~2.5% in 30 min. This technique provides a path to generate broadband laser sources at shorter wavelengths which are potentially useful for biomedical and spectroscopic applications.