Methods, apparatus, and systems for active saturable absorbance of an optical beam. An active saturable absorber may comprise an optical input to receive an optical beam, and one or more lengths of fiber between the optical input and an optical output. At least one of the lengths of fiber comprises a confinement region that is optically coupled to the output. The active saturable absorber may further comprise an optical detector to sense a characteristic of the optical beam, such as power. The active saturable absorber may further comprise a perturbation device to modulate, through action upon the one or more lengths of fiber, a transmittance of the beam through a fiber confinement region from a lower transmittance level to a higher transmittance level based on an indication of the characteristic sensed while the transmittance level is low.

Methods, apparatus, and systems for modulation of a laser beam. An optical modulator may comprise an optical input to receive an optical beam, and one or more lengths of fiber between the optical input and an optical output. At least one of the lengths of fiber comprises a confinement region that is optically coupled to the output. The optical modulator may further comprise a perturbation device to modulate, through action upon the one or more lengths of fiber, a transmittance of the beam through the confinement region from a first transmittance level at a first time instance to a second transmittance level at a second time instance. The optical modulator may further comprise a controller input coupled to the perturbation device, wherein the perturbation device is to act upon the one or more lengths of fiber in response to a control signal received through the controller input.

Apparatuses and methods are disclosed for applying laser energy having desired pulse characteristics, including a sufficiently short duration and/or a sufficiently high energy for the photomechanical treatment of skin pigmentations and pigmented lesions, both naturally-occurring (e.g., birthmarks), as well as artificial (e.g., tattoos). The laser energy may be generated with an apparatus having a resonator with the capability of switching between a modelocked pulse operating mode and an amplification operating mode. The operating modes are carried out through the application of a time-dependent bias voltage, having waveforms as described herein, to an electro-optical device positioned along the optical axis of the resonator.

Apparatuses and methods are disclosed for applying laser energy having desired pulse characteristics, including a sufficiently short duration and/or a sufficiently high energy for the photomechanical treatment of skin pigmentations and pigmented lesions, both naturally-occurring (e.g., birthmarks), as well as artificial (e.g., tattoos). The laser energy may be generated with an apparatus having a resonator with the capability of switching between a modelocked pulse operating mode and an amplification operating mode. The operating modes are carried out through the application of a time-dependent bias voltage, having waveforms as described herein, to an electro-optical device positioned along the optical axis of the resonator.

The disclosed method and apparatus for stabilizing a mode-locked regime of a fiber ring oscillator based on a NPR include tapping a portion of light, which has a broad spectral bandwidth, from a fiber ring resonator into at least first and second control channels. The control channels are configured to guide respective first and second fractions of the tapped portion. One of the control channels is provided with a bandpass filter operative to extract a region from the broad spectral bandwidth. The fractions with respective full spectral bandwidth and region thereof are then evaluated in a central processing unit which is operable to generate a control signal if a predetermined criterion is not met. The control signal is received by one or more polarization controller units operative to dynamically modulate a state of polarization of light in the fiber ring resonator until the evaluation meets the predetermined criterion.

A stabilized laser source includes a fiber-ring Brillouin laser that incorporates a circulator for non-reciprocal operation and for launching of a pump optical signal. Most of the pump optical signal is launched in a forward direction and drives Brillouin laser oscillation in the backward direction, a portion of which exits via an optical coupler as the optical output of the laser source. A small fraction of the pump optical signal is launched in the backward direction via the optical coupler, and a fraction of that backward-propagating pump optical signal exits via the optical coupler as an optical feedback signal. A frequency-locking mechanism receives the optical feedback signal and controls the pump optical frequency to maintain resonant propagation of the backward-propagating pump optical signal. A second pump optical signal can be launched in the forward direction to generate a second Brillouin laser oscillation.

A mode-locked laser (MLL) that produces ultra-low phase noise optical and RF outputs, includes two nested resonant optical cavities including an optical fiber-based cavity and an etalon, and a three bandwidth Pound-Drever-Hall (PDH) frequency stabilizer assembly incorporating three different optical bandpass filters. The optical fiber-based cavity is characterized by a free spectral range, FSR.sub.fiber, and the etalon is characterized by a free spectral range, FSR.sub.filter, wherein FSR.sub.filter/FSR.sub.fiber is an integer equal to or greater than 2. A method of generating ultra-low phase noise optical and RF outputs is disclosed. Optical and RF outputs have a phase noise that is less than 100 dBc/Hz at 1 Hz and less than 150 dBc at 10 KHz.

According to aspects of the disclosure, an apparatus, system and method for stabilising the length of a plurality of optical cavities is provided. The apparatus comprises an optical light source configured to output an incident light beam. The apparatus also includes a separating means configured to receive the incident light beam output from the optical source and split the received incident light beam so as to output two or more light beams. The apparatus further includes a plurality of optical cavities, where each optical cavity of the plurality of optical cavities is configured to receive one of the light beams output from the separating means and transmit or reflect a portion of light indicative of whether the optical cavity is on resonance with the optical light source. Each optical cavity is also configured to contain a matter qubit within the optical cavity. Each matter qubit is configured to capture photons to distribute quantum entanglement, where a rate of entanglement is enhanced by the Purcell effect. Each optical cavity is further configured to be connected to an actuator. The actuator is configured to tune the length of the optical cavity based on the portion of light transmitted or reflected from the optical cavity to be on resonance with the optical source in order to lock the optical cavity to the optical source. The matter qubit is the same for each optical cavity. The incident light beam is detuned by a ratio of two integers, a and b where a b denotes a fixed fraction, from a transition wavelength of the matter qubit to ensure that, for each optical cavity, there is at least one point within a travel range of the actuator where a dual-resonance condition is met such that the optical cavity is simultaneously resonant with the matter qubit and the incident light beam.

According to aspects of the disclosure, an apparatus, system and method for stabilising the length of a plurality of optical cavities is provided. The apparatus comprises an optical light source configured to output an incident light beam. The apparatus also includes a separating means configured to receive the incident light beam output from the optical source and split the received incident light beam so as to output two or more light beams. The apparatus further includes a plurality of optical cavities, where each optical cavity of the plurality of optical cavities is configured to receive one of the light beams output from the separating means and transmit or reflect a portion of light indicative of whether the optical cavity is on resonance with the optical light source. Each optical cavity is also configured to contain a matter qubit within the optical cavity. Each matter qubit is configured to capture photons to distribute quantum entanglement, where a rate of entanglement is enhanced by the Purcell effect. Each optical cavity is further configured to be connected to an actuator. The actuator is configured to tune the length of the optical cavity based on the portion of light transmitted or reflected from the optical cavity to be on resonance with the optical source in order to lock the optical cavity to the optical source. The matter qubit is the same for each optical cavity. The incident light beam is detuned by a ratio of two integers, a and b where a b denotes a fixed fraction, from a transition wavelength of the matter qubit to ensure that, for each optical cavity, there is at least one point within a travel range of the actuator where a dual-resonance condition is met such that the optical cavity is simultaneously resonant with the matter qubit and the incident light beam.

A method and a system for automatically controlling mode-locking of an optical frequency comb, where the stored control parameters of the working condition in the mode-locked state is combined with the collected working feedback parameters of the optical frequency comb system to dynamically adjust and control the working power of the pump source or/and the temperature of the working environment of the pump source, which not only greatly shortens the control time for stable mode-locking and realizes a fast mode-locking control, but also reduces unnecessary power consumption, thereby further guaranteeing the energy-saving effect of power adjustment control process. The present disclosure well maintains the stable working conditions of the optical comb system, and realizes the mode-locking optimization control of an update mode for the big data, thereby effectively improving the mode-locking control process of the optical frequency comb system, and providing higher operation stability and measurement accuracy.