Continuous tuning of a continuous-wave periodically poled lithium niobate optical parametric oscillator by use of a fan-out grating design

We report on a new periodically poled lithium niobate grating design with a continuous grating-period change (fan-out). We observed $350 {\mathrm{cm}}^{-1}$ (80 nm at $1.5 \mathit{\mu }\mathrm{m}$) of complete spectral coverage at a constant temperature in a cw optical parametric oscillator. Complete spectral coverage is demonstrated by measurement of an absorption band of ${\mathrm{CO}}_2$.