Optical device and optical apparatus

An optical apparatus, comprising:

• an optical device including a demultiplexing unit that performs demultiplexing into a plurality of optical signals having wavelengths different from each other;
• and
• a controller coupled to the optical device;
• wherein
• the demultiplexing unit includes:
• a plurality of optical filters that are coupled in multiple stages and in which a period of a peak wavelength of a transmission spectrum differs among different stages;
• a monitoring optical filter coupled to one of the plurality of optical filters;
• a monitoring photodetector coupled to the output side of the monitoring optical filter;
• and
• a plurality of wavelength adjustment units that are provided individually for the plurality of optical filters and the monitoring optical filter and cause wavelength shifts of an equal amount in a same direction;
• and
• the controller performs control for the plurality of wavelength adjustment units based on a value detected by the monitoring photodetector.