Wavelength dispersive device with temperature compensation

A fiber optic wavelength dispersive device comprising:

• a front-end unit comprising a first port for launching an input optical signal;
• a wavelength dispersive reflector for receiving the input optical signal, for dispersing the input optical signal into a plurality of sub-beams of light with different central wavelengths, and for directing said sub-beams back at first angles along first optical paths in a dispersion plane;
• a spherical reflector for redirecting the input optical signal launched from the first port to the wavelength dispersive reflector, and for redirecting the sub-beams from the wavelength dispersive reflector back along second spatially separated optical paths;
• and,
• an array of beam receiving elements for receiving each of the sub-beams at a different location along the array according to the central wavelength thereof;
• wherein the wavelength dispersive reflector comprises:
• a transmissive dispersion grating (TDG) for receiving the input optical signal and for transmitting each of the plurality of sub-beams of light at a different angle of diffraction,
• a reflective surface spaced from the TDG for reflecting the plurality of sub-beams of light back through the TDG, and
• a first wedged prism of an optically transparent material for refracting each of the sub-beams of light in the dispersion plane at an angle of refraction dependent on the temperature of the device, the first wedged prism having an apex angle;
• wherein a shift in the angles of refraction of the sub-beams provided by the first wedged prism due to a change in the temperature of the device at least partially compensates for a shift in the angles of diffraction caused by the change in the temperature of the device.