Various example embodiments relate to the field of fiber laser technology. A fiber laser may comprise an active optical fiber configured to amplify an optical signal and a frequency shifter, which may be optically coupled to the active optical fiber. The frequency shifter may be configured to cause a frequency shift to the optical signal in a first direction. The fiber laser may further comprise a bandpass filter, which may be optically coupled to the frequency shifter. The bandpass filter and the active optical fiber may be configured to induce a reverse frequency shift to the optical signal in a second direction opposite to the first direction.

A novel broadly tunable optical parametric oscillator is described for use in numerous applications including multi-photon microscopy. The optical parametric oscillator includes at least one sub-picosecond laser pump source configured to output a pump signal having a wavelength of about 650 nm or less and at least one type II optical parametric oscillator in optical communication with the pump source and configured to generate a single widely tunable pulsed optical signal. In one application, an optical system is in optical communication with the optical parametric oscillator and configured to direct at least a portion of the optical signal to a specimen, and at least one analyzing device is configured to receive a signal from the specimen in response to the optical signal.

A high-power ytterbium-doped calcium fluoride laser system is disclosed herein which includes at least one pump source, at least one laser cavity formed by at least one high reflector and at least one output coupler, and at least one ytterbium-doped calcium fluoride optical crystal positioned within the laser cavity in communication with the pump source, the ytterbium-doped calcium fluoride optical crystal configured to output at least one output signal of at least 20 W, having a pulse width of 200 fs or less, and a repetition rate of at least 40 MHz.

A method for generating femtosecond vortex beams with high spatial intensity contrast, where a noncollinearly pumped HG beam femtosecond laser generates femtosecond HG beam and a cylindrical lens mode converter converts the femtosecond HG beam to femtosecond LG vortex beam. The HG beam femtosecond laser comprises a pump source, a gain medium, a saturable absorption mirror as mode-locker, and an output coupler with a noncollinear angle between the laser beam and the pump beam in the gain medium, which enables the laser to generate pure, order-tunable femtosecond HG beams. Femtosecond vortex beams obtained after the cylindrical lens converter have high-intensity-contrast, and are topological charge-tunable.

A system for optical comb carrier envelope offset frequency control includes a mode-locked laser and a frequency shifter. The mode-locked laser produces a laser output. The frequency shifter shifts the laser output to produce a frequency shifted laser output based at least in part on one or more control signals. The frequency shifted laser output has a controlled carrier envelope offset frequency. The frequency shifter includes a first polarization converter, a rotating half-wave plate, and a second polarization converter.

Apparatus, systems, and methods of operating a fiber laser having polarization-preserving fibers can be applied as a sensor to detect a physical quantity. In various embodiments, polarization-preserving fibers can provide a laser cavity having an interferometer disposed in the laser cavity. In various embodiments, a fiber optical parametric oscillator can include an interferometer disposed in the cavity of the optical parametric oscillator. Additional apparatus, systems, and methods are disclosed.

A mid-infrared cascading fiber amplifier device having a source configured to generate a first electromagnetic wave output at a first frequency, a fiber coupled to the source and a pump coupled to the fiber and configured to generate a second electromagnetic wave output at a second frequency, wherein the second frequency is higher than the first frequency and causes the fiber to undergo two or more transitions in response to stimulation by the first electromagnetic wave output at the first frequency, wherein the first transition generates the first electromagnetic wave output approximately at the first frequency and the second transition generates the first electromagnetic wave output approximately at the first frequency.

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.

Provided are a saturable absorber including at least one material selected from a group of MXenes, and a Q-switching and mode-locked pulsed laser system using the same.

An unidirectional short-wave infrared fiber laser, comprising a theta cavity, with a gain unit based on rare-earth cations-doped fiber, the theta cavity having a ring cavity with two additional 2 input ports2 output ports directional couplers DC1 and DC2 inserted therein, one port of the directional coupler DC1 connected to another port of the directional coupler DC2, forming an S-shaped feedback; a band-pass filter to select at a laser wavelength by filtering through transmission inside the theta cavity, the band-pass filter is one of the list comprising a grating-based filter, a Fabry-Perot etalon, and a phase shifted fiber-Bragg grating; and a reflective fiber Bragg grating (FBG) to select the laser wavelength by filtering through reflection inside the theta cavity, the Bragg grating is a notch filter, and the fiber Bragg grating (FBG) is attached to an unused port of the directional coupler DC1 or DC2.