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.

The present disclosure describes an optical waveguide provided with an incident side reflection film and an emission side reflection film to resonate light incident via the incident side reflection film and formed to penetrate from the incident side reflection film to the emission side reflection film for propagating resonated light. The disclosure also includes a substrate to which the optical waveguide is formed from a top surface thereof and a first protection member and a second protection member formed with a material corresponding to a material of the substrate, wherein the first protection member and the second protection member are arranged on the optical waveguide such that one end facet of the first protection member forms an identical plane with a first end facet of the substrate including an optical incident end.

Provided are a laser device and an optical apparatus including the same. The laser device includes a pump light source configured to provide pump light, a gain medium configured to acquire a gain of seed laser light by using the pump light, a first curved mirror and a second curved mirror, which are provided at both sides of the gain medium to reflect the seed laser light into the gain medium, an output mirror configured to transmit a portion of the seed laser light reflected by the second curved mirror and reflect the other portion of the seed laser light to the gain medium, a first acoustic wave generator connected to the gain medium and configured to provide a first photoacoustic wave in the gain medium, and a second acoustic wave generator connected to the gain medium and configured to provide a second photoacoustic wave in the gain medium.

Provided are a laser device and an optical apparatus including the same. The laser device includes a pump light source configured to provide pump light, a gain medium configured to acquire a gain of seed laser light by using the pump light, a first curved mirror and a second curved mirror, which are provided at both sides of the gain medium to reflect the seed laser light into the gain medium, an output mirror configured to transmit a portion of the seed laser light reflected by the second curved mirror and reflect the other portion of the seed laser light to the gain medium, a first acoustic wave generator connected to the gain medium and configured to provide a first photoacoustic wave in the gain medium, and a second acoustic wave generator connected to the gain medium and configured to provide a second photoacoustic wave in the gain medium.

A measurement apparatus that includes a laser apparatus outputting a frequency-modulated laser beam, a branching part branching the frequency-modulated laser beam into a reference light and a measurement light, a beat signal generation part generating a beat signal by mixing the reference light and a reflected light that is reflected by radiating the measurement light onto an object to be measured, an extraction part extracting a signal component corresponding to a resonator frequency of the frequency-modulated laser beam, a clock signal generation part generating a first clock signal on the basis of the signal component, a conversion part converting the beat signal into a first digital signal using the first clock signal, and a calculation part calculating a difference in a propagation distance between the reference light and the measurement light on the basis of the first digital signal.

An electrically tunable non-reciprocal phase shifter, an electrically tunable polarization filter, a NALM mode-locked laser and a Sagnac loop are provided. The electrically tunable non-reciprocal phase shifter includes a modulation crystal device, a birefringent crystal device, a Faraday rotator, and a fiber coupler. The phase shifter is configured to couple two beams of light to a fast axis and a slow axis of the modulation crystal device, respectively; and change a refractive index difference between the fast axis and the slow axis to introduce different phase delays for the two beams of the light, so as to control a non-reciprocal linear phase shift amount between the two beams of the light.

A synthesizer including a controller configured to receive a first signal. A digital-to-analog converter (DAC) is coupled to the controller and is configured to generate a voltage bias based on the first signal. The voltage bias corresponds to a target resonant frequency. A semiconductor laser is coupled to the DAC and is configured to receive a second signal tone. The semiconductor laser generates a plurality of tone signals having octave multiples of a base sub-harmonic tone of the second signal tone.

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.