Patent ID: 7983314
Filing Date: 2011-07-19
Classification: H01S

Abstract:
1. A laser, comprising: an optical polarization beam splitter (PBS) having a first port, a second port and a third port, wherein light at a first optical polarization transmits through the PBS between the first port and the second port, and light at a second optical polarization orthogonal to the first optical polarization that enters the first port is directed to the third port; a first optical path having a first end and a second end, the first end optically coupled to the first port of the PBS to direct light into the first port of the PBS and to receive light in the first optical polarization that transmits through the PBS from the second port to the first port; a polarization reflector coupled to the second end of the first optical path to reflect light received from the first optical path back to the first optical path with a reflected optical polarization that is orthogonal to a polarization of the light that initially enters the first optical path upon exiting the first port of the PBS; a second optical path having a first end and a second end, the first end optically coupled to the third port of the PBS to receive light in the second optical polarization from the third port and to direct the received light to the second; an optical circulator having a first port, a second port and a third port to direct light received at the first port to output at the second port and to direct light received at the second port to output at the third port, the first port being optically coupled to the second end of the second optical path to direct light from the second optical path to the second port; an optical unit optically coupled to the second port of the optical circulator to receive light and to direct a returned light beam back to the second port of the optical circulator; a third optical path connected between the third port of the optical circulator and the second port of the PBS to direct the returned light beam from the optical unit at the third port of the optical circulator to the second port of the PBS which directs the light in the first optical polarization in the third optical path from the second port of the PBS to the first port of the PBS; an optical amplifier coupled in at least one of the first, second and third optical paths to amplify light to cause a laser oscillation in light circulating from the polarization reflector, to the PBS via the first optical path, to the optical circulator via the second optical path, to the optical unit, to the optical circulator, to the PBS via the third optical path, and to the polarization reflector an optical monitor module coupled to one of the first, second and third optical paths to receive a fraction of the light to split the received fraction of the light into a first monitor light beam and a second monitor light beam, the optical monitor module including (1) an optical power detector to receive the first monitor light beam to produce an output indicating a power level of the light and (2) a laser frequency monitor to receive the second monitor light beam to measure a laser frequency of the light.