Systems and methods for controlling the optical path length between a laser and an optical cavity

Inventors

Koulikov, Serguei

Assignees

Li Cor Inc

Abstract

Systems and methods for controlling the optical path length between a feedback enabled laser and a cavity, and hence the optical feedback phase. A phasor element, positioned along an optical path between the laser and the cavity coupling mirror, includes a gas medium within a volume defined by the phasor element. The phasor element is configured to adjust or control an optical path length of the laser light between the laser and the cavity coupling mirror by adjusting or controlling a density of the gas medium within the phasor volume.

Core Innovation

The invention provides an optical spectroscopy system that uses an optical feedback responsive laser with a resonant optical cavity having at least two cavity mirrors, one of which is a cavity coupling mirror. Mode matching optics couple the laser light to the cavity through the cavity coupling mirror, while the laser is responsive to optical feedback light emerging from the cavity. A detector measures an intensity of intracavity optical power of light circulating in the cavity and generates a signal representing the intracavity optical power of light circulating in the cavity.

The optical path length between the laser and the cavity coupling mirror is controlled using a phasor element positioned along an optical path between the laser and the cavity coupling mirror. The phasor element includes a gas medium within a volume defined by the phasor element, and adjusts or controls the optical path length of the laser light by adjusting or controlling a density of the gas medium within the volume.

Changing the gas medium density varies the laser-cavity optical distance and thereby controls the optical feedback phase without piezo actuators. The cavity is described in multiple geometries including V-shaped, linear, and ring cavities, and the detector is configured to measure intracavity optical power including ring-down events. The system enables trace gas analysis based on cavity loss differences, using the detector signal representing the intracavity optical power circulating in the cavity.

Claims Coverage

The partial set identifies two independent claims that cover an optical spectroscopy system and a method for controlling an optical path length, with additional dependent claim refinements specifying detector operation, laser type, cavity geometry, and how the gas-medium density is controlled.

Across the identified independent claims, the main claim coverage is directed to controlling the optical path length between a laser and a cavity coupling mirror by using a phasor element containing a gas medium whose density is adjusted, while using mode-matching optics to couple a cavity-feedback responsive laser to a resonant cavity and measuring intracavity optical power to generate a signal.

Stated Advantages

Documented Applications