Optical device incorporating a tilted bragg grating

A device for measuring a characteristic of light within an operating wavelength range, the device comprising:

• a waveguide for supporting the light propagating therein, the light having a wavelength within the operating wavelength range, the waveguide having an optical axis;
• a Bragg grating formed in the waveguide for coupling at least a portion of the light out of the waveguide through a side surface thereof, and for dispersing thereby formed out-coupled light azimuthally about the optical axis;
• photo-detecting means disposed for detecting an azimuthal distribution of the out-coupled light about the optical axis;
• wherein the Bragg grating has a period selected for providing a maximum out-coupling efficiency at a Bragg wavelength located outside of the operating wavelength range, and so that the azimuthal distribution of the out-coupled light is substantially wavelength dependent and changes when the wavelength is changed within the operating wavelength range;
• and,
• processing means for receiving information from the photo-detecting means and for determining the wavelength from the detected azimuthal distribution of the out-coupled light that was coupled out of the waveguide by the Bragg grating.