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Publication Number
US-11441944-B2
Publication Date
2022-09-13
Expiration Date
Abstract
Systems and methods for controlling optical feedback in an optical system. A resonant optical cavity includes at least two cavity mirrors, one of which is a cavity coupling mirror, and has a plurality of optical resonance cavity modes. A radiation source emits a beam of continuous wave radiation and is capable of being scanned whereby a mean optical frequency of the continuous wave radiation beam is adjustable over a range of frequencies, wherein the radiation source is responsive to optical feedback radiation emerging from the cavity, and wherein the mode matching optics couples the beam of continuous wave radiation to the cavity via the cavity coupling mirror. The radiation source and the mode matching optics are aligned so that a mode fill ratio is reduced relative to a maximum mode fill ratio, wherein the laser beam is coupled with a fundamental cavity mode.
Core Innovation
The invention controls optical feedback in an optical system by aligning a radiation source and mode matching optics that couple continuous wave radiation into a resonant optical cavity having at least two cavity mirrors and a cavity coupling mirror. The resonant optical cavity supports a plurality of optical resonance cavity spatial modes, and the radiation source is responsive to optical feedback radiation emerging from the cavity and impinging on the radiation source. The radiation source emits continuous wave radiation and is capable of being scanned so that the mean optical frequency is adjustable over a range of frequencies.
In the method, aligning is performed to control an amount of optical feedback radiation emerging from the resonant optical cavity so that a mode fill ratio of optical feedback spectral modes is reduced relative to a maximum mode fill ratio. The maximum mode-fill ratio is defined as coupling of the continuous wave radiation to a fundamental cavity spatial mode. By reducing the mode fill ratio relative to that maximum condition, optical feedback in the optical system is controlled to mitigate the participation of optical feedback spectral modes.
An optical system and a gas analyzer are also provided that implement the same principle using mode matching optics and an adjustment mechanism configured to adjust a relative position of the radiation source relative to the at least one component of the mode matching optics. The adjustment mechanism is configured to control the amount of optical feedback radiation emerging from the resonant optical cavity, thereby reducing the mode fill ratio of optical feedback spectral modes relative to a maximum mode fill ratio associated with coupling to a fundamental cavity spatial mode. A detector measures the intensity of intracavity optical power and generates a signal representing the intracavity optical power circulating in the resonant optical cavity.
Claims Coverage
The document includes three independent claims (one method claim, two apparatus claims: an optical system and a gas analyzer). Across these independent claims, the coverage consistently features controlling optical feedback by aligning/adjusting mode matching into a resonant optical cavity so that the mode fill ratio of optical feedback spectral modes is reduced relative to a maximum condition defined by coupling to a fundamental cavity spatial mode; the optical system and gas analyzer further include an adjustment mechanism and, in the gas analyzer, a detector for intracavity optical power.
Aligning to reduce mode fill ratio of optical feedback spectral modes
A method of controlling optical feedback by aligning a radiation source and mode matching optics so that continuous wave radiation, scanned to adjust mean optical frequency and responsive to optical feedback radiation emerging from the cavity, is coupled via a cavity coupling mirror into a resonant optical cavity; the alignment controls an amount of optical feedback radiation such that a mode fill ratio of optical feedback spectral modes is reduced relative to a maximum mode fill ratio, where for the maximum mode-fill ratio the beam is coupled with a fundamental cavity spatial mode.
Adjustment mechanism for relative position control to reduce mode fill ratio
An optical system having a resonant optical cavity with at least two cavity mirrors (including a cavity coupling mirror) and a plurality of optical resonance cavity modes, a continuous wave radiation source scanned to adjust mean optical frequency and responsive to optical feedback radiation, and mode matching optics that couple the beam to the cavity via the cavity coupling mirror; an adjustment mechanism coupled with at least one component of the mode matching optics and/or the radiation source adjusts a relative position of the radiation source relative to the mode matching optics to control an amount of optical feedback radiation emerging from the resonant optical cavity, reducing a mode fill ratio of optical feedback spectral modes relative to a maximum mode fill ratio, where for the maximum mode-fill ratio the beam is coupled with a fundamental cavity spatial mode.
Gas analyzer with intracavity power detector and mode fill ratio reduction
A gas analyzer including a resonant optical cavity configured to receive a gaseous medium including one or more analyte species, a continuous wave radiation source scanned to adjust mean optical frequency and responsive to optical feedback radiation emerging from the cavity, and mode matching optics coupling the continuous wave radiation to the resonant optical cavity via the cavity coupling mirror; an adjustment mechanism adjusts a relative position of the radiation source relative to the mode matching optics to control optical feedback radiation such that a mode fill ratio of optical feedback spectral modes is reduced relative to a maximum mode fill ratio, where for the maximum mode-fill ratio the beam is coupled with a fundamental cavity spatial mode; and a detector measures intensity of intracavity optical power of radiation circulating in the resonant optical cavity and generates a signal representing the intracavity optical power.
Across the independent claims, the core inventive theme is controlling optical feedback by aligning/adjusting mode matching between a continuous-wave, frequency-scannable radiation source and a resonant cavity so that the mode fill ratio of optical feedback spectral modes is reduced relative to a maximum mode-fill ratio corresponding to coupling to a fundamental cavity spatial mode.
Stated Advantages
Provides controlling of optical feedback in an optical system by reducing the mode fill ratio of optical feedback spectral modes relative to a maximum mode fill ratio.
In a gas analyzer, enables measurement of intracavity optical power via a detector that generates a signal representing the intracavity optical power circulating in the resonant optical cavity.
Documented Applications
Gas analyzer for receiving a gaseous medium including one or more analyte species and using the resonant optical cavity, continuous-wave scanned radiation, and mode fill ratio reduction to control optical feedback.
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