Apparatus and method for achieving a smooth spectral response optical filter

A low-ripple and low-loss spectral response optical filter including one grating means connected to a reflector unit by a set of optical elements substantially periodically spaced by a distance “a”, the grating further characterized in that

• the aperture of each grating is substantially equal to fλ/a, where λ is the wavelength of interest and f is the focal length of the grating means.

A low-ripple and low-loss spectral response optical filter including two waveguide grating routers connected by a set of waveguides, each waveguide grating router comprising a pair of star couplers interconnected by a waveguide grating, each waveguide grating router further characterized in that

• the number of grating arms in the waveguide grating is chosen so as to fill, not substantially more or substantially less, the central Brillouin zone of each star coupler as determined by the set of connecting waveguides for which one desires a low-ripple and low-loss spectral response.

A low-ripple and low-loss spectral response optical filter including waveguide grating routers connected by a set of waveguides to a reflecting means, each waveguide grating router comprising a pair of star couplers interconnected by a waveguide grating, each waveguide grating router further characterized in that

• the number of grating arms in the waveguide grating is chosen so as to fill, not substantially more or substantially less, the central Brillouin zone of each star coupler as determined by the set of connecting waveguides for which one desires a low-ripple and low-loss spectral response.

A method of producing a low-ripple and low-loss spectral response optical filter from two waveguide grating routers connected by a set of waveguides, each waveguide grating router comprising a pair of star couplers interconnected by a waveguide grating, the method including the steps of:

• determining the set of connecting waveguides for which one desires a ripple-free and low-loss spectral response and
• selecting the number of grating arms in the waveguide grating so as to fill, not substantially more or substantially less, the central Brillouin zone of each star coupler, as determined by the set of connecting waveguides.

A method of producing a low-ripple and low-loss spectral response optical filter from a waveguide grating routers connected by a set of waveguides to a reflecting means, each waveguide grating router comprising a pair of star couplers interconnected by a waveguide grating, the method including the steps of:

• determining the set of connecting waveguides for which one desires a ripple-free and low-loss spectral response and
• selecting the number of grating arms in the waveguide grating so as to fill, not substantially more or substantially less, the central Brillouin zone of each star coupler, as determined by the set of connecting waveguides.