Disclosed herein is an all-fiber, easy to use, wavelength tunable, ultrafast laser based on soliton self-frequency-shifting in an Er-doped polarization-maintaining very large mode area (PM VLMA) fiber. The ultrafast laser system may include an all polarization-maintaining (PM) fiber mode-locked seed laser with a pre-amplifier; a Raman laser including a cascaded Raman resonator and an ytterbium (Yb) fiber laser cavity; an amplifier core-pumped by the Raman laser, the amplifier including an erbium (Er) doped polarization maintaining very large mode area (PM Er VLMA) optical fiber and a passive PM VLMA fiber following the PM Er VLMA, the passive PM VLMA for supporting a spectral shift to a longer wavelength.

An optical assembly provides dispersion control, modelocking, spectral filtering, and/or the like in a laser cavity. For example, the optical assembly may comprise a diffraction grating pair arranged to temporally and spatially disperse a beam on a forward pass through the optical assembly, a reflective device at an end of the optical assembly, and a focusing optic arranged to create a beam waist at the reflective device. The beam waist created at the reflective device may cause the beam to be inverted on a reverse pass through the optical assembly, and a temporal dispersion and a spatial dispersion of the beam may be doubled on the reverse pass through the optical assembly to form a temporally and spatially dispersed output from the optical assembly.

The present disclosure is related to field of Fiber Feedback (FFB) technology, and provides a method and system for estimating the distance between a fiber end and a target. The method includes illuminating, by a Light Emitting, Transmitting and Detecting (LETD) system, the target with laser light of different wavelengths having low and high water absorption coefficients, using different laser light sources, as well as receiving a returned signal corresponding to the incident laser light of different wavelengths, and detecting the returned signal to measure intensity values of the returned signal of a specific wavelength. Using the measured intensity values, a processing unit may estimate distance between the fiber end and the target. The present disclosure enables accurate estimation of distance between a fiber end and the target. The present disclosure also provides a robust distance estimation technique which is compatible with different types of targets.

Methods and apparatus for providing spectrally beam-combined fiber-based transmitters and/or receivers for laser communications, LiDAR, and similar devices. A transmitter can include a launch array configured to spatially position each output beam of pulsed lasers, a transform optical component to correct deflection of the output beams of the pulsed lasers from the launch array, and a dispersive optical element to combine beams from the transform optical element and generate a spectrally combined beam. A receiver can include spectral comb filters to spectrally discriminate multi-wavelength detected signals from background illumination.

The disclosure describes aspects of laser cavity repetition rate tuning and high-bandwidth stabilization of pulsed lasers. In one aspect, an output optical coupler is described that includes a cavity output coupler mirror, a piezoelectric actuator coupled to the cavity output coupler mirror, a locking assembly within which the cavity output coupler mirror and the piezoelectric actuator are positioned, and one or more components coupled to the locking assembly. The components are configured to provide multiple positional degrees of freedom for tuning a frequency comb spectrum of the pulsed laser (e.g., tuning a repetition rate) by adjusting at least one position of the locking assembly with the cavity output coupler mirror. A method of adjusting an output optical coupler in a pulsed laser is also described. These techniques may be used in different applications, including quantum information processing.

A system includes a processor communicatively coupled to an Amplifier Stimulated Emission (ASE) source and an optical receiver, wherein the processor is configured to cause transmission of one or more shaped ASE signals, from the ASE source, on an optical fiber, obtain received spectrum of the one or more shaped ASE signals from the optical receiver connected to the optical fiber, and characterize the optical fiber based in part on a nonlinear skirt and/or center dip depth in the received spectrum of the one or more shaped ASE signals. The one or more shaped ASE signals can be formed by the ASE source communicatively coupled to a Wavelength Selective Switch (WSS) that is configured to shape ASE from the ASE source to form the one or more shaped ASE signals with one or two or multiple peaks and with associated frequency.

A femtosecond laser multimodality molecular imaging system includes a near-infrared pulse generation device for providing near-infrared pulses with a central wavelength of 1010 nm to 1100 nm and a spectral width of less than 25 nm. The near-infrared pulses can excite an optical medium with strong nonlinearity to generate the femtosecond laser pulses with ultra-wide spectrum. A pulse measurement compression and control module measures and compensates the accumulated dispersion of the femtosecond laser pulses arriving at the tissue sample, so as to eliminate the “time domain broadening” effect as much as possible. The obtained shortest pulses can interact with the tissue sample to generate spectral signals from different modalities, thus providing a variety of nonlinear molecular image modalities.

A fiber laser system based in solitonic passive mode-locking, including a laser diode to emit and deliver an optical signal of a first wavelength; a single-fiber laser cavity including a dichroic mirror, a SESAM and a polarization maintaining highly-doped active fiber, to receive the emitted signal and to emit a pulsed optical signal of a second wavelength, generating laser light in the form of mode-locked ultrashort pulses; a unit coupling the laser diode to the single-fiber laser cavity; and an isolator device protecting the cavity from back reflections. The solitonic mode-locked ultrashort pulses are comprised in a range of 100 fs<10 ps with repetition rates of hundreds MHz to tens of GHz.

Examples of compact control electronics for precision frequency combs are disclosed. Application of digital control architecture in conjunction with compact and configurable analog electronics provides precision control of phase locked loops with reduced or minimal latency, low residual phase noise, and/or high stability and accuracy, in a small form factor.

An apparatus can be provided which can include a laser arrangement which can be configured to provide a laser radiation, and can include an optical cavity. The optical cavity can include a dispersive optical first arrangement which can be configured to receive and disperse at least one first electro-magnetic radiation so as to provide at least one second electro-magnetic radiation. Such cavity can also include an active optical modulator second arrangement which can be configured to receive and modulate the at least one second radiation so as to provide at least one third electro-magnetic radiation. The optical cavity can further include a dispersive optical third arrangement which can be configured to receive and disperse at least one third electro-magnetic radiation so as to provide at least one fourth electro-magnetic radiation. For example, actions by the first, second and third arrangements can cause a spectral filtering of the fourth electro-magnetic radiation(s) relative to the first electro-magnetic radiation(s). The laser radiation can be associated with the fourth radiation(s), and a wavelength of the laser radiation can be controlled by the spectral filtering caused by the actions by the first, second and third arrangements.