CW demonstration of SHG spectral narrowing in a PPLN waveguide generating 2.5 W at 780 nm

Abstract

Periodically poled lithium niobate (PPLN) waveguides are a proven and popular means for efficient wavelength conversion. However, conventional PPLN waveguides typically have small mode field diameters (MFD) (≲6 µm) or significant insertion and/or propagation losses, limiting their ability to operate at multi-watt power levels. In this work we utilise zinc indiffused PPLN ridge waveguides that have a larger MFD, favourable pump/SHG modal overlap, and low insertion losses. Here for the first time, we have demonstrated continuous wave (CW) spectral narrowing from a PPLN waveguide; both with high efficiency and multi-watt second harmonic generation (SHG). 2.5 W of 780 nm has been produced by SHG of an amplified 1560 nm telecom laser with a device efficiency of 58% in a 4.0 cm-long ridge waveguide. We have modelled conversion efficiency and applied experimentally measured waveguide parameters to show excellent agreement to the SHG spectra. Spectral narrowing of the full width half maximum (FWHM) of 35.7% has been measured as the nonlinear drive is increased. This work demonstrates that single-pass, multi-watt, CW SHG at 780 nm is feasible from our PPLN waveguide in the large conversion regime.

375-400nm SHG Alexandrite laser using Zn-indiffused MgO:PPLN ridge waveguides

“…Znindiffused MgO-doped PPLN waveguides have recently emerged as a scalable approach for generating highefficiency watt-level visible laser output. 2 We believe that combining these two technologies can provide a compact and efficient single-stage SHG laser system with wide wavelength flexibility in the UVA range.…”

Single PPLN SHG waveguide for full C band tuning range with watt level output through the engineered QPM structure

“…MgO-doped periodically poled lithium niobate (MgO:PPLN) ridge waveguide technology for nonlinear wavelength conversion is attractive due to the high conversion efficiency and moderate power handling, which is highly suitable to combine with the common watt-level CW fiber laser in C band to generate watt-level SHG output in the 780nm region [1,2]. Through the state of the art fiber pigtailed technology, compact and robust fiber input/output optical device can be easily fabricated, which plays an important role for applications such as quantum computing and laser cooling.…”

Efficient watt-level 0.775 μm SHG and 3.3 μm DFG in annealed and reverse proton exchanged diced PPLN ridge waveguides

“…Regarding frequency doubling of 1550 nm light, impressive peak conversion efficiencies of up to 4600 %/W have been reported [1,2]. On the other hand, watt-level second-harmonic generation (SHG) outputs, have been demonstrated in PPLN waveguides with relatively low efficiencies of (50 -100) %/W [3,4]. PPLN waveguides both with channel and ridge geometries, have been also used for generation of mid-infrared (MIR) light in the (3.2 -4) µm wavelength range through difference frequency generation (DFG) of the two pump waves with wavelengths around 1050 nm and 1550 nm.…”