Systems and methods are provided for creating a sequence of turn-up processes for amplifiers. A method, according to one implementation, includes determining when a fiber span is initially installed in an optical line system or when an Optical Line Failure (OLF) in the fiber span has recovered. The optical line system includes a first set of amplifiers deployed at an upstream node and a second set of amplifiers deployed at a downstream node, the upstream node connected to the downstream node via the fiber span. In response to determining that the fiber span is initially installed in the optical line system or that an ORL in the fiber span has recovered, the method also includes sending a flag from the upstream node to the downstream node to allow the first set of amplifiers to perform a first turn-up process before the second set of amplifiers perform a second turn-up process.

An optical device includes first and second 45° Faraday rotators. A 45° polarizer is located between the first and second Faraday rotators such that light in a prescribed polarization state that is incident on the first 45° Faraday rotator traverses the first 45° Faraday rotator as well as the 45° polarizer and the second 45° Faraday rotator. In one implementation the optical device is operable to receive a light beam traveling in a first direction and output a light beam that is in a predetermined polarization state. Likewise, the optical device is operable to receive an unpolarized light beam traveling in a second direction opposite the first direction and outputs a light beam that is in a predetermined polarization state. The polarization state in which the two output beams are arranged may be the same or orthogonal to one another.

Systems and methods are provided for amplifying optical signals within one of two optical bands, such as C-band and L-band. An optical amplifying device, according to one implementation, may include a shared optical coil configured to propagate an optical signal. The optical amplifying device may further include a first junction configured to separate the shared optical coil into a first-band optical fiber and a second-band optical coil and a pump device configured to amplify the optical signal in the shared optical coil and the second-band optical coil. The first-band optical fiber may be configured to propagate the optical signal when the optical signal resides in a channel of a first plurality of channels within a first optical band. The second-band optical coil may be configured to propagate the optical signal when the optical signal resides in a channel of a second plurality of channels within a second optical band.

A figure-8 laser is configured in which gain in the uni-directional loop can be removed while maintaining mode-locked operation with gain only in the bi-directional nonlinear amplifying loop. Simplified self-starting and control over pulse characteristics by controlling gain in the bi-directional loop is made possible.

Disclosed is a pulsed laser apparatus and method of generating a laser pulse. The apparatus includes an input coupler configured to receive pumping light from a pumping light source and a seed pulse from a seed pulse generator. The apparatus further includes a doped fiber-optic cable with an input port at a first end configured to receive the pumping light and the seed pulse. The doped fiber-optic cable amplifies the seed pulse to generate an output pulse. Along a first length of the doped fiber optic cable, the pulse spectrum broadens rapidly owing to nonlinearity. Beyond the first length in an extended portion, the output pulse shifts towards longer wavelengths and broadens in both spectral and temporal domains The apparatus also includes an output port at a second end of the doped fiber-optic cable, wherein the output pulse exits the doped fiber-optic cable at the output port.

An optical amplification apparatus includes a first amplification optical fiber, a second amplification optical fiber, a first pumping light source, and a second pumping light source. The first amplification optical fiber includes a first core and a first cladding layer. The first core is doped with an active element using a first active element doping concentration distribution. The first cladding layer is disposed out of the first core and has a refractive index lower than the refractive index of the first core. The second amplification optical fiber is connected to the first amplification optical fiber in a longitudinal direction of the first amplification optical fiber. The second amplification optical fiber includes a second core and a second cladding layer. The second core is doped with active element using a second active element doping concentration distribution that is different from the first active element doping concentration distribution.

A first fiber is connected to a first end of a third fiber doped with a rare earth element, and a second fiber is connected to a second end of the third fiber. In the third fiber doped with the rare earth element, a central portion of a core is more heavily doped with the rare earth element than a peripheral portion of the core is.

Provided is an output adjustment device for a laser lithotripsy apparatus including: a processor including hardware, the processor being configured to: pulse a laser beam; adjust an output of the pulsed laser beam; monotonically increase the output of the laser beam as a first period to generate a bubble binding body containing a plurality of bubbles from a laser emission end; monotonically decrease the output of the laser beam with a gradient larger than a predetermined gradient as a second period following the first period to cause the bubble binding body to disappear so that a crushing target is attracted to the laser emission end; and before the bubble binding body is generated, raise a liquid temperature in a region where the bubble binding body is generated by generating the bubbles and causing the bubbles to disappear.

Provided is a waveform control device for a laser lithotripsy apparatus including: a processor including hardware, the processor being configured to: pulse a laser beam; change an output of the pulsed laser beam; continuously emit the laser beam until a bubble generated from a laser emission end by an irradiation of the laser beam reaches a crushing target; and after the bubble generated from the laser emission end reaches the crushing target, reduce the output of the laser beam or turn off the irradiation of the laser beam during a period in which there is the bubble between the laser emission end and the crushing target, and the bubble does not couple the laser emission end and the crushing target.

An all solid hybrid waveguiding structure provides large mode area, acceptable losses of the desired core mode and very high losses of the undesired next higher order mode in the core. Embodiments of the waveguide include a hybrid of low index barriers providing confinement by total internal reflection, and further include high index rings that support guided modes only at effective indices different from that of the desired core mode.