Abstract: There is provided a laser, and/or a reflector for a laser cavity comprising: a ring resonator structure; and a Fabry-Perot filter connected in cascade to the ring resonator structure by a coupling waveguide. The coupling waveguide is configured to propagate light having a frequency corresponding to any of the resonant frequencies of the ring resonator structure to the Fabry-Perot filter, and the Fabry-Perot filter is configured to select one or more frequencies and return light having a frequency matching any of the selected frequencies to the ring resonator structure via the coupling waveguide.

Abstract: A signal generator for a phased array antenna comprises a laser light source arranged to provide an optical spectrum comprising a plurality of spaced wavelengths. The signal generator further comprises a dispersion unit arranged to introduce a delay to a plurality of spectral components of the optical spectrum associated with the spaced wavelengths. The delay is dependent on the wavelength of the spectral components of the optical spectrum. The signal generator further comprises a heterodyning device configured to generate a signal for the phased array antenna by heterodyning the spectral components associated with different ones of the spaced wavelengths of the laser light source.

Abstract: A signal generator for a phased array antenna comprises a laser light source arranged to provide an optical spectrum comprising a plurality of spaced wavelengths. The signal generator further comprises a dispersion unit arranged to introduce a delay to a plurality of spectral components of the optical spectrum associated with the spaced wavelengths. The delay is dependent on the wavelength of the spectral components of the optical spectrum. The signal generator further comprises a heterodyning device configured to generate a signal for the phased array antenna by heterodyning the spectral components associated with different ones of the spaced wavelengths of the laser light source.