Patent ID: 8472496

Claim:
A device which is composed of: (a) a reflector providing at least one reflectivity stopband, (b) a gain region with means for generating optical gain introduced into said reflector, said gain region having a gain spectrum overlapping with the spectral range of the reflectivity stopband, (c) a medium attached to said reflector, and (d) an interface between said reflector and said medium, wherein optical emission impinging to the reflector from said medium partially penetrates into the reflector, and wherein the reflectivity of the reflector for a light with a wavelength within the reflectivity stopband is an increasing function of a tilt angle between a propagating direction of the light within said medium and a direction normal to said interface, such that, among a photon propagating within said medium at a first tilt angle and a photon propagating in said medium at a second tilt angle, wherein said second angle is larger than said first angle, amplification of said photon propagating at said first angle by said gain region is stronger than amplification of said photon propagating at said second angle.