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.

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 demonstrate bandwidth broadening in cascaded MgO-doped periodically poled lithium niobate (MgO:PPLN) crystals ($\mathrm{\Lambda }=10.3\mathrm{\mu m}$) using the temperature-gradient technique. Up to 2.8 nm bandwidth at 600 nm spectral region is achieved using two 50 mm long cascaded MgO:PPLN crystals via sum frequency generation. This technique combines the merits of high conversion efficiency attributed to cascaded nonlinearity and the reconfigurability of temperature-gradient-induced chirp for broadening of the input wavelength acceptance range.

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.

We demonstrate a compact blue and orange-two color continuous wave laser source emitting at 487 nm and from 597.4 to 600.3 nm, respectively. The temperature tunable coherent orange radiation is achieved by frequency mixing 974 nm laser diode (LD) and a C-band amplified spontaneous emission laser source while the temperature insensitive blue radiation is generated by second-order quasi-phase-matching frequency doubling of 974 nm LD. We implement the simultaneous nonlinear processes in a single magnesium oxide doped periodically poled lithium niobate bulk crystal without the need of an aperiodic design.

We report on simultaneous sum-frequency mixing and doubling of C-band and ∼ 980 n m laser sources using a single segmented periodically poled lithium niobate (PPLN) crystal in a single-pass configuration. Our theoretical analysis on the spectral outputs show that a proper design of a five-segment single PPLN crystal has potential to generate violet, blue, green, and orange wavelengths by simultaneous sum-frequency and second-harmonic generation processes. Such a design has promising potential for a compact, tunable multicolored laser that can find various applications such as in biomedicine, visible light communications, laser-based color displays, and sensing.