A bidirectional mode-locked fiber laser includes first and second passive optical fibers, a doped optical fiber, first and second polarization controllers, and first and second polarized beamsplitters that are arranged as a ring cavity with clockwise (CW) and counter-clockwise (CCW) directions. The laser imparts different nonlinear phase shifts in the CW and CCW directions, corresponding to CW and CCW repetition rates that are slightly different. When the normalized difference in repetition rates is less than approximately 10.sup.−5, both directions can be mode-locked simultaneously, thereby preventing one direction from inhibiting mode-locking of the other direction. Optical-fiber nonlinearity implements an intra-cavity bidirectional artificial saturable absorber based on nonlinear polarization rotation. The laser uses only components with normal group-velocity dispersion (GVD), thereby achieving higher pulse energies than mode-locked lasers utilizing negative GVD. The combination of artificial saturable absorber and normal GVD components increases pulse energy, which improves the efficiency of spectral broadening.

A bidirectional mode-locked fiber laser includes first and second passive optical fibers, a doped optical fiber, first and second polarization controllers, and first and second polarized beamsplitters that are arranged as a ring cavity with clockwise (CW) and counter-clockwise (CCW) directions. The laser imparts different nonlinear phase shifts in the CW and CCW directions, corresponding to CW and CCW repetition rates that are slightly different. When the normalized difference in repetition rates is less than approximately 10.sup.−5, both directions can be mode-locked simultaneously, thereby preventing one direction from inhibiting mode-locking of the other direction. Optical-fiber nonlinearity implements an intra-cavity bidirectional artificial saturable absorber based on nonlinear polarization rotation. The laser uses only components with normal group-velocity dispersion (GVD), thereby achieving higher pulse energies than mode-locked lasers utilizing negative GVD. The combination of artificial saturable absorber and normal GVD components increases pulse energy, which improves the efficiency of spectral broadening.

A high-precision repetition rate locking apparatus for an ultra-fast laser pulse includes: an electronic controlling component comprising: a standard clock, configured to provide a high-precision frequency standard; a pulse generator (PG), configured to provide an electrical pulse signal with adjustable repetition rate, pulse width and voltage magnitude; and a signal generator (SG), connected to the standard clock and the PG, and configured to provide a stable frequency signal for the PG, a phase-shift adjusting component, connected to the electronic controlling component and configured to implement phase modulation through electrically induced refractive index change; a resonant cavity component, comprising a phase shifter, a doped fiber, a laser diode, a wavelength division multiplexer and a reflector, and configured to generate a mode-locked pulse; and a detection system, configured to measure a repetition rate of an output pulse.

Systems and methods for temporal amplitude modulation of an optical beam. An exemplary system may include a birefringent fiber positioned between two polarizers, or between a polarized input light source and an output polarizer. Light may enter the birefringent fiber as linearly polarized. Depending on birefringence and orientation of the birefringent fiber, the polarization state changes as the light propagates through the birefringent fiber. This changed polarization state then enters the output polarizer, for which transmission is a function of the polarization state and the relative orientation of the polarization axis. The polarization state emerging from the birefringent fiber may be changed by modulating the fiber birefringence, for example through application of an external stress. Net transmittance of the system may be varied according to a magnitude of an external force (e.g., pressure) to some or all of the birefringent fiber.

A method of generating an optical pulse train using spectral extension by optical phase modulation, spectral narrowing by optical phase demodulation, and narrow linewidth optical filtering is disclosed. It is also described that the wavelength selection of light using a chromatic dispersion element between the optical phase modulator can enrich the method. Systems include an in-line optical setup and a ring-type laser cavity for mode-locked laser outputs. The duration with which the electrical signals driving the modulators are opposed determines the line width of the optical pulses, and the opposite repetition of the electrical signals defines the rate of repetition of an optical pulse train generated. Four different arrangements of electrical signals in the time domain or phase domain make it possible to control the generation of optical pulses and the wavelength selection of the light. (i) A signal arrangement comprising sinusoidal electrical signals with a slight frequency difference. (ii) A signal arrangement comprising a phase-shift between electrical signals. (iii) A signal arrangement comprising a phase-shift between electrical signals depending on the amplitude of the bits. (iv) A signal arrangement comprising random electric waves that repeat themselves over a predefined period to allow the insertion of controllable time delays between each other.

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.

Disclosed herein is a single pulse laser apparatus that includes: a resonator having a first mirror, a second mirror, a gain medium, an electro-optic modulator (EOM) configured to perform single pulse switching, and an acousto-optic modulator (AOM) configured to perform mode-locking; a photodiode configured to measure a laser beam oscillated in the resonator; a synchronizer configured to convert an electrical signal, which is generated by measuring the laser beam, into a transistor-transistor logic (TTL) signal; a delay unit configured to set a delay time for the TTL signal to synchronize the EOM and the AOM and output a trigger TTL signal according to the delay time; an AOM driver configured to input the trigger TTL signal to the AOM that performs mode-locking and drive the AOM; and an EOM driver configured to input the trigger TTL signal to the EOM that performs single pulse switching and drive the EOM.

Provided is a single pulse laser apparatus. The apparatus including a resonator having a first mirror, a second mirror, a gain medium, and electro-optic modulators (EOMs) which perform each mode-locking and Q-switching, the apparatus includes a photodiode which measures laser light that oscillates from the resonator, a synchronizer which converts an electrical signal generated by measuring the laser light into a transistor-transistor logic (TTL) signal, a delay unit which sets a latency determined in order to synchronize a mode-locked pulse with a Q-switched pulse to the TTL signal, and outputs a trigger TTL signal according to the latency, and a Q-driver which inputs the trigger TTL signal to the EOM which performs Q-switching, and causes the EOM to operates.

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.

A laser for emitting simultaneously a first and second laser lights having respectively first and second wavelength differing from each other. The laser comprises: an optical resonator defining a first optical path and a second optical path, the first laser light travelling along the first optical path and the second laser light travelling along the second optical path; a modulated gain element inserted in the optical resonator for amplifying the first and second laser lights as the first and second laser lights propagate in the optical resonator respectively along the first and second optical paths, the modulated gain element having a variable gain modulated with a modulation period, round trip times of the first and second laser lights along respectively the first and second optical paths being respective integer multiples of the modulation period; and an output port for releasing the first and second laser lights from the optical resonator.