Methods, systems and apparatus are disclosed for delivery of pulsed treatment radiation by employing a pump radiation source generating picosecond pulses at a first wavelength, and a frequency-shifting resonator having a lasing medium and resonant cavity configured to receive the picosecond pulses from the pump source at the first wavelength and to emit radiation at a second wavelength in response thereto, wherein the resonant cavity of the frequency-shifting resonator has a round trip time shorter than the duration of the picosecond pulses generated by the pump radiation source. Methods, systems and apparatus are also disclosed for providing beam uniformity and a sub-harmonic resonator.

An optical device includes first and second 45° Faraday rotators. A 45° polarizer is located between the first and second Faraday rotators such that light in a prescribed polarization state that is incident on the first 45° Faraday rotator traverses the first 45° Faraday rotator as well as the 45° polarizer and the second 45° Faraday rotator. In one implementation the optical device is operable to receive a light beam traveling in a first direction and output a light beam that is in a predetermined polarization state. Likewise, the optical device is operable to receive an unpolarized light beam traveling in a second direction opposite the first direction and outputs a light beam that is in a predetermined polarization state. The polarization state in which the two output beams are arranged may be the same or orthogonal to one another.

An optical device includes first and second 45° Faraday rotators. A 45° polarizer is located between the first and second Faraday rotators such that light in a prescribed polarization state that is incident on the first 45° Faraday rotator traverses the first 45° Faraday rotator as well as the 45° polarizer and the second 45° Faraday rotator. In one implementation the optical device is operable to receive a light beam traveling in a first direction and output a light beam that is in a predetermined polarization state. Likewise, the optical device is operable to receive an unpolarized light beam traveling in a second direction opposite the first direction and outputs a light beam that is in a predetermined polarization state. The polarization state in which the two output beams are arranged may be the same or orthogonal to one another.

Methods, systems and apparatus are disclosed for delivery of pulsed treatment radiation by employing a pump radiation source generating picosecond pulses at a first wavelength, and a frequency-shifting resonator having a losing medium and resonant cavity configured to receive the picosecond pulses from the pump source at the first wavelength and to emit radiation at a second wavelength in response thereto, wherein the resonant cavity of the frequency-shifting resonator has a round trip time shorter than the duration of the picosecond pulses generated by the pump radiation source. Methods, systems and apparatus are also disclosed for providing beam uniformity and a sub-harmonic resonator.

Example embodiments relate to lasers that include loop resonators. One example laser includes a loop resonator forming a closed loop light path. The loop resonator includes an optical gain medium configured to lase. The loop resonator is configured to, during lasing, present a pair of modes: a mode of light propagating in a clockwise direction in the closed loop light path of the loop resonator (termed CW mode) and a mode of light propagating in a counter-clockwise direction in the closed loop light path of the loop resonator (termed CCW mode). The laser also includes a first light output configured to output laser light from the laser. Additionally, the laser includes an optical power modulating unit. The optical power modulation unit is configured to modulate an optical power of the CW mode of the loop resonator and an optical power of the CCW mode of the loop 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.

An ultrafast mode-locked laser comprising circuitry configured to drive an electro-optic modulator (EOM) in the mode-locked laser with a drive waveform, the drive waveform being a phase-coherent sinusoidal waveform at a frequency equal to a repetition rate of the mode-locked laser, a phase-coherent pulsed waveform at a frequency equal to the repetition rate of the mode-locked laser, or a phase-coherent sinusoidal waveform at a frequency equal to half of the repetition rate of the mode-locked laser.

Free-space optical (FSO) wireless transmission, including optical communications, remote-sensing, power beaming, etc., can be enhanced by replacing conventional laser sources that operate in the infrared portion of the optical spectrum with ultra-short pulsed laser (USPL) sources having peak pulse powers of one kWatt or greater and pulse lengths of less than one picosecond. Specifically, it has been observed that under these conditions the attenuation of an USPL beam having the same average optical power as a conventional laser in a lossy medium, such as the atmosphere, is substantially less than the attenuation of a conventional laser beam having a lower peak pulse power and/or a longer pulse width. The superior system performance when using an USPL can be translated into an increased distance between a laser source in a transmitter and a photodetector in receiver and/or a higher reliability of system operation in inclement weather conditions.

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 (e.g., a Pockels cell) positioned along the optical axis of the resonator.

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.