An all-fiber supercontinuum (SC) optical source utilizes a combination of a seed pulse supply of short-duration optical pulses with a highly non-linear optical medium in the form of two or more concatenated sections of highly non-linear optical fiber (HNLF) of different dispersion values and lengths. The two or more sections of HNLF are configured to include at least one section that exhibits a positive dispersion value and one section that exhibits a negative dispersion value. Non-linear effects such as self-phase modulation (SPM), cross-phase modulation (XPM), Raman amplification, and the like, cause the seed pulses to broaden as they propagate through each section of HNLF, where the differences between the dispersion values, as well as the lengths of each fiber section, are particularly configured to create an SC output that is wide and smooth, exhibiting a stable intensity and high coherence level.

An apparatus includes an amplified spontaneous emission source, which in turn includes an optical fiber. The optical fiber includes a solid core and a first end. The solid core includes a silica matrix. The silica matrix includes a rare-earth element and a glass co-dopant. The rare-earth element includes dysprosium or neodymium. The glass co-dopant includes Al.sub.2O.sub.3. The apparatus further includes a laser pump diode coupled to the first end of the optical fiber. The laser pump diode and the optical fiber cooperate to generate a spontaneous spectral emission confined to the solid core. The spontaneous spectral emission includes a simultaneous plurality of spectral regions.

Techniques for extending distributed acoustic sensing (DAS) range in undersea optical cables are provided. For example, DAS range can be extended by transmitting and amplifying a DAS signal along multiple spans of a first optical fiber, routing or bypassing the DAS signal from the first optical fiber to a second optical fiber different from the first fiber via a high-loss loopback architecture, and returning and amplifying the DAS signal along the same multiple spans back to a DAS device. The DAS device may then receive and process the DAS signal to detect any changes in the DAS environment. The loopback configuration may be based on different types of loopback architecture.

The invention belongs to the field of lasers, more precisely to the field of constructional details of laser devices and laser devices for controlling intensity, frequency, length, polarization or direction of emitted rays. The present invention is an improved gain switched fiber laser, which enables changes of repetition frequency in a large range and which, at the same time, maintains a constant peak power and duration of generated laser pulses. The essence of the laser according to the invention is the pump system which is coupled to an oscillator and pumps the oscillator as well as the amplifier. The pump system comprises a primary and a secondary pump module, each at least with one pump laser diode, wherein the primary module generates short pump pulses and wherein the primary and secondary pump module operate at different peak powers. The power generated by the secondary module can be directly used to decrease the effect of active medium relaxation via spontaneous emission in-between laser pulses, which enables generation of short laser pulses on demand having constant parameters.

An active element-doped optical fiber includes: a core that includes first and second regions. The first region ranges from a central axis to a predetermined radius, and is doped with an active element excited by excitation light. The second region surrounds the first region with no gap, extends to an outer peripheral surface of the core, and is not doped with the active element. The core satisfies 0.1 d<ra<d, where ra is a radius of the first region and d is a radius of the core. The core has, in a region of 0.2 d<r≤0.9 d, a maximum value position at which a refractive index becomes maximum, where r is a distance from a central axis of the core in a radial direction.

The present invention discloses a high-peak-power single-frequency narrow-linewidth nanosecond fiber laser based on a triangular pulse, wherein the laser includes: pulsed laser generated by the laser seed injecting into a first power pre-amplifier through a first isolator, and then injecting into a second pre-amplifier and then injecting into a power amplifier; wherein triangle-shaped pulsed laser with fast rising edge is obtained by using electro-optic and acousto-optic modulator to modulate continuous wave single-frequency laser or a single-frequency semiconductor laser directly modulated by radio frequency signal; single-frequency triangle-shaped pulsed laser is employed as the laser source according to the characteristics of narrow intrinsic linewidth and suppression of linewidth broadening caused by SPM, and the power of pulsed laser is amplified through the MOPA system.

A wavelength-tunable, polarization-maintaining (PM) fiber laser for use in the two micron wavelength region is based upon a ring laser geometry and includes sections of polarization-maintaining (PM) optical fiber for supporting propagation of the circulating laser radiation around the ring. At least one gain module is included in the ring and is formed of polarization-maintaining active optical fiber including a core region that is doped with either Thulium (Tm) or Holmium (Ho), or co-doped with both of these rare earth materials. In the presence of a pump beam operating at a suitable wavelength, the gain module(s) generate laser radiation at a wavelength within the two micron region. A PM-based tunable bandpass filter (BPF) is included within the ring and used to control/adjust the wavelength of the output beam provided by the fiber laser.

Embodiments discussed herein refer to LiDAR systems and methods that enable substantially instantaneous power and frequency control over fiber lasers. The systems and methods can simultaneously control seed laser power and frequency and pump power and frequency to maintain relative constant ratios among each other to maintain a relatively constant excited state ion density of the fiber laser over time.

The present disclosure provides a tunable broadband random optoelectronic oscillator, including: a laser light source configured to generate continuous laser light; a positive feedback loop formed by an intensity modulator, an optical circulator, an optical filter, an optical amplifier, a photodetector, an electric filter and an electric amplifier connected in sequence, wherein the positive feedback loop is configured to receive the continuous laser light to generate a microwave signal and achieve an optic-electro/electro-optic conversion; a Raman laser configured to generate Raman pump light; a wavelength division multiplexer having a first input terminal connected to the Raman laser and a second input terminal connected to the optical circulator; and a dispersion compensation fiber connected to an output terminal of the wavelength division multiplexer; wherein forward transmission laser light passing through the optical circulator and the Raman pump light are coupled into the dispersion compensation fiber through the wavelength division multiplexer.

The technology of this application relates to the field of communication technologies, and an optical fiber raw material composition, an optical fiber, and an optical fiber product. The optical fiber raw material composition includes components of the following molar percentages: AlF.sub.3 10%-50%, BaF.sub.2 3%-20%, CaF.sub.2 3%-20%, YF.sub.3 1%-15%, SrF.sub.2 3%-20%, MgF.sub.2 3%-20%, and TeO.sub.2 1%-35%. The optical fiber prepared by using the optical fiber raw material composition provided in this disclosure can be used in aspects such as a mid-infrared band transmission optical fiber, an optical fiber amplifier, a fiber laser, and an optical fiber sensor.