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.

An optical system allows sharing of optical components and seed and pump light to achieve desired optical amplification in laser light while reducing the number of optical components and complexity of the overall optical system and achieving improved performance in lasers and reduced cost in fabrication and final lasers for large scale production of such lasers. Different optical gain sections can be used to allow for sharing of seed and pump light and sharing of optical components while providing multi-stage optical amplification.

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.

A sensing method for in-situ non-perturbing measurement of characteristics of laser beams at the exit of the laser beam delivery fiber tips include measuring power of a laser beam transmitted through delivery fiber tip in fiber-optics systems. A sensing devices for in-situ non-perturbing sensing and control of multiple characteristics of laser light transmitted through light delivery fiber tips includes a fiber-tip coupler comprised of a shell with enclosed delivery fiber having a specially designed angle-cleaved endcap and one or several tap fibers that are specially arranged and assembled at back side of the endcap and other variations. Methods and system architectures for in-situ non-perturbing control of characteristics of laser beams at the exit of the laser beam delivery fiber tips include fiber-tip couplers and sensing modules that receive laser light from tap fibers, and systems for optical processing to enhance light characteristics suitable for in-situ measurement.

A multi-clad optical fiber is provided. The fiber includes, concentrically and radially outwards from the center of the optical fiber, a core doped with at least one rare-earth dopant material, a pedestal cladding structure, an inner cladding and an outer cladding. The pedestal cladding structure includes a pedestal layer having a refractive index smaller than a refractive index of the core, and a raised index layer having a refractive index larger than the refractive index of the pedestal layer. The raised index layer has a thickness and a refractive index which preserve the confinement of the core mode in the core and minimize the overlap of one or more pedestal modes with the core.

The present disclosure provides a waveguide integrated optical modulator, which is made of a bismuth film, an antimony film, or a tellurium film. A thickness of the bismuth film, the antimony film, or the tellurium film is between 10 nm and 200 nm, and the bismuth film, the antimony film, or the tellurium film is produced by physical vapor deposition method. The waveguide integrated optical modulator can directly add the symmetrical electrode on the surface of the bismuth film, the antimony film, or the tellurium film, and apply an external bias voltage of different amplitudes to the bismuth film, the antimony film, or the tellurium film by adjusting the power source. Thus, the waveguide integrated optical modulator can actively control the nonlinear optical characteristics of the saturable absorber by changing the magnitude of the external voltage, and further actively modulate the laser characteristics of the pulse.

A fiber-based optical amplifier for operation at an eye-safe input signal wavelength λ.sub.S within the 2 μm region is formed to include a section of Holmium (Ho)-doped optical gain fiber. The pump source for the fiber amplifier is particularly configured to provide pump light at a wavelength where the absorption coefficient of the Ho-doped optical gain fiber exceeds its gain coefficient (referred to as an “absorption-dominant pump wavelength”), and is typically within the range of 1800-1900 nm. The selection of an absorption-dominant pump wavelength limits the spontaneous emission of the pump from affecting the amount of gain achieved at the higher wavelength end of the operating region. The amount of crosstalk between the signal wavelength and pump wavelength is also reduced (in comparison to using the conventional 1940 nm pump wavelength).

A higher-order mode (HOM) fiber is configured as a polarization-maintaining fiber by including a pair of stress rods at a location within the cladding layer that provides for a sufficient degree of birefringence without unduly comprising the spatial mode profile of the propagating higher-order modes. An optical imaging system utilizing polarization-maintaining HOM fiber allows for different wavelength probe signals to be directed into different modes, useful in applications such as STED microscopy, 2D sensing, and the like.

The present invention provides an active fiber package for use in a fiber laser, amplifier, or ASE source comprising: a plate-shape base comprising a groove having a configuration of at least two spirals for receiving and fixedly holding an active fiber therein, said at least two spirals are coplanar enabling visibility of said active fiber, the outer loop of one spiral transitioning smoothly to the outer loop of another spiral, and the inner loop of each one of said spirals transitioning smoothly into a relatively short straight section; wherein a portion of said straight section of one of said spirals spliced to a coupling fiber, and wherein multiple inner loops of each one of said spirals in proximity to said straight section having a relatively low radius of curvature for enabling tight coiling of said active fiber, thus, for reducing thermal modal instability (TMI) and increasing lasing power.

Disclosed is an all-fiber optical vortex laser based on resonance of orbital angular momentum modes. The all-fiber optical vortex laser has an annular cavity structure, and includes a narrow-linewidth pump laser, an optical amplifier, an orbital angular momentum mode generator, a first polarization controller, an optical fiber circulator, an optical fiber coupler, a second polarization controller and a vortex optical fiber. The orbital angular momentum mode generator (3) realizes directional conversion from a fundamental transverse mode in a single-mode optical fiber into an orbital angular momentum mode with a specific topological charge in a vortex optical fiber. The optical fiber coupler can realize directional coupling from an orbital angular momentum mode in one vortex optical fiber to an orbital angular momentum mode in another vortex optical fiber; the vortex optical fiber is an optical fiber supporting stable transmission of an orbital angular momentum model.