Diffraction-grating-type phase converters for conversion of Hermite-Laguerre-Gaussian mode into Gaussian mode.

Diffraction gratings that can be used to convert the Hermite-Laguerre-Gaussian (HLG) mode into the Gaussian mode were obtained; these modes are space modes of light beams. The HLG mode is intermediate between the Hermite-Gaussian and the Laguerre-Gaussian modes. Generally, gratings produced from interfering two beams as holograms contain information of not only the phase modulation factor but also the amplitude modulation factor. Thus, they cannot be expected to provide high conversion efficiency. To produce high-efficiency gratings, the interference equation is divided into two factors. The gratings produced by considering only the phase factors act as phase converters.