Optical heterodyne detection in optical cavity ringdown spectroscopy

An optical apparatus including:

• a continuous-wave laser source for emitting radiation;
• a ringdown cavity cell, said cell defining a resonant optical cavity in optical communication with said laser;
• means for directing a portion of said radiation emitted from said light source into said optical cavity of said ringdown cavity cell;
• means for coupling and decoupling said radiation into said optical cavity without using an optical switch or modulator;
• means for generating a frequency shift of the radiation in the optical cavity without using an optical modulator;
• means for optically combining a portion of said radiation emitted from said laser source and which has not been emitted from said optical cavity with frequency shifted ringdown cavity radiation which is emitted from the optical cavity, wherein the combined radiation is capable of optical heterodyne detection;
• and
• means for optical heterodyne detection of said combined radiation.

A method for optical detection including:

• emitting radiation from a continuous-wave laser source;
• directing a portion of said radiation emitted from said laser into a resonant optical cavity of a ringdown cavity cell, said resonant optical cavity in optical communication with said laser,
• coupling and decoupling said radiation into said optical cavity without using an optical switch or modulator;
• generating a frequency shift of the radiation in the optical cavity without using an optical modulator;
• optically combining a portion of said radiation emitted from said laser source and which has not been emitted from said optical cavity with frequency shifted ringdown cavity radiation which is emitted from the optical cavity, wherein the combined radiation is capable of optical heterodyne detection;
• and
• optically heterodyne detecting said combined radiation.

An optical apparatus including:

• at least two continuous-wave laser sources for emitting laser radiation, each source operating at a different wavelength;
• a ringdown cavity cell, said cell defining a resonant optical cavity in optical communication with said at least two lasers;
• means for directing a portion of said laser radiation emitted from said at least two lasers into said optical cavity of said ringdown cavity cell;
• means for coupling and decoupling said laser radiation into said optical cavity;
• means for generating a frequency shift of the laser radiation in the optical cavity without using an optical modulator;
• means for optically combining a portion of said laser radiation emitted from said laser source and which has not been emitted from said optical cavity with frequency shifted ringdown cavity laser radiation which is emitted from the optical cavity, wherein the combined radiation is capable of optical heterodyne detection;
• and
• means for optical heterodyne detection of said combined radiation.

An optical apparatus including:

• at least one continuous-wave laser source for emitting laser radiation at a specified wavelength;
• at least two ringdown cavity cells, each cell defining a resonant optical cavity in optical communication with at least one of said continuous-wave lasers;
• means for directing a portion of said laser radiation emitted from said laser into an optical cavity of at least one of the ringdown cavity cells;
• means for coupling and decoupling said laser radiation to said optical cavity;
• means for generating a frequency shift of the laser radiation in the optical cavity without using an optical modulator;
• means for optically combining a portion of said laser radiation emitted from said laser source and which has not been emitted from said optical cavity with frequency shifted ringdown cavity laser radiation which is emitted from the optical cavity, wherein the combined radiation is capable of optical heterodyne detection;
• and
• means for optical heterodyne detection of said combined radiation.