Grating periods measurement of multi-pitched grating using Littrow configuration external cavity diode laser
Shuzo Masui, Shuhei Goda, Shotaro Kadoya, Masaki Michihata, Satoru Takahashi
Abstract
A simple measurement technique is proposed for multi-pitched grating inserted in an external cavity diode laser. Measuring grating rotation and variation of multiple resonant wavelengths enables us to estimate grating periods and Littrow angles simultaneously. We experimentally determined that sufficient variation of resonant wavelength (i.e. ∼1.6 nm) could be obtained even with a grating rotation less than 0.05°. The grating periods and Littrow angles of two dual-period holographic gratings were successfully measured with less than 1% error. This technique can be applied to the motionless measurement of multi-pitched gratings, diffractive optics, and metasurfaces in the future.