Patent ID: 9748726
Date: 2017-08-29
CPC Classifications: H01S

Claim:
1. A source of coherent radiation, comprising: an optical resonant cavity having a gain element with one partially reflecting mirror for reflecting a part of radiation back inside the cavity and partially outputting a laser emission; a directional coupler, the coupler splitting incoming radiation into clockwise and counterclockwise beams: both beams passing through a Sagnac loop: the loop incorporating at least a first, a second and a third microresonator rings interconnected via intermediate bus waveguides so that none of the rings directly couples to one another: the first ring, the second ring and the third ring having different sets of resonant frequencies; and wherein one resonant frequency is common for all three rings and there is no other common resonant frequency over a wavelength range of at least 40 nm; the first ring, the second ring and the third ring circumferences optimized for required laser performance; the clockwise and counterclockwise beams recombine coherently in the directional coupler: the coupler outputs an obtained combined beam into the gain element: the gain element outputting the laser emission that has a linewidth less than 10 kHz, wherein the linewidth is determined by optimized selection of all ring circumferences and coupling coefficients between all rings and all busses.