A wavelength-variable laser outputting a predetermined wavelength of laser light includes: a quantum well active layer positioned between a p-type cladding layer and an n-type cladding layer in thickness direction; a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer; and an electric-field-distribution-control layer positioned between the separate confinement heterostructure layer and the n-type cladding layer and configured by at least two semiconductor layers having band gap energy greater than band gap energy of a barrier layer constituting the quantum well active layer.

An amplifier includes a first monitor configured to measure first optical power including first signal light and ASS light of a first wavelength band propagated through the amplification medium, and a processor configured to calculate the first ASS light power corresponding to the first excitation light power, based on the determined first model formula, calculate the second ASS light power corresponding to the second excitation light power, based on the determined second model formula, calculate the first signal light power by subtracting the calculated first ASS light power and second ASS light power from the first optical power measured by the first monitor, and calculate a difference between the calculated first signal light power and first target signal light power, and controll a first excitation light source or a second excitation light source to adjust the first excitation light power or the second excitation light power based on the difference.

A method of propagating a laser signal through an optical waveguide and a waveguide laser system provide a novel way of stabilizing the beam emitted by a fiber laser system above the mode instability threshold wherein the beat length of two or more interfering transverse modes of the laser signal in the optical waveguide is modulated in time.

An optical transmission device includes: a first drive unit that drives a VOA adjusting an attenuation amount for an optical signal from an optical amplifier; a second drive unit that drives an excitation light source of the optical amplifier; a first FF control unit that sets a first set value for the first drive unit and performs FF control; a second FF control unit that sets a second set value for the second drive unit and performs the FF control; a first control unit that controls the second drive unit in a manner that causes an optical output power from the optical amplifier to attain a first control target value; and a switch unit that switches to the first control unit when the optical output power corresponding to the second set value is attained as a result of FF control of the second FF control unit.

A laser oscillator of the present invention comprises: a semiconductor laser module; a first optical fiber for propagating a laser beam from the semiconductor laser module; and a first prism including a first input surface fusion-bonded to the first optical fiber and receiving the laser beam having been input from the first optical fiber, a first reflection surface for reflecting the laser beam having been input from the first input surface and for transmitting a stimulated Raman scattered beam, and a first output surface for outputting the laser beam having been reflected on the first reflection surface.

A smart spool is configured to be optically coupled between a pumping light source and optical point-loss sources in an optical fiber transmission line. The smart spool comprises a probe signal transmitter that transmits an optical probe signal into the transmission line. An optical detector receives probe signals scattered in the transmission line. A loss-measuring device is coupled to the optical detector and operable to measure aggregate losses in the transmission line and report the aggregate losses to a network manager. The spool comprises a fiber of sufficient length to offset the aggregated losses to enable a distributed Raman amplifier to pump the transmission line. The smart spool prevents the distributed Raman amplifier from shutting down and allows the distributed Raman amplifier to achieve entitled gain by pumping the fiber in the spool.

A laser diode system includes plurality of laser pumps, each of the plurality of laser pumps including a plurality of laser diode drivers and a plurality of laser diode elements, wherein each of the plurality of laser diode drivers is electrically coupled to power at least two of the plurality of laser diode elements. A combiner electrically is coupled to the plurality of laser diode elements to combine an output of each of the plurality of laser pumps to generate a combined output light. A controller identifies a failed laser pump or a failed laser diode element, receives an encoded key to gain access to the controller, and disables the failed laser pump or the failed laser diode element based at least in part on authenticating the encoded key.

A cascade control system of an optical fiber amplifier includes a target setting parameter module, a primary controller, at least one controlled module and a secondary controller corresponding to the controlled module. The control system adopts two or more cascade control loops so that disturbance entering into the secondary loop can be overcome quickly, thereby the dynamic characteristics of the system may be improved. The primary controller aims to coarse adjustment and overall target control, and the secondary controller aims to fine adjustment and quick convergence of a short-term target, so that the control quality of the cascade control system may be further improved. The cascade control system may define the overall control target directly in the primary loop and avoid impact of aging characteristics of some special parameters on the application.

An optical amplifier that amplifies a wavelength multiplexing optical signal includes a first rare-earth-doped fiber, a second rare-earth-doped fiber connected in series with the first rare-earth-doped fiber, an excitation light combiner that inputs core excitation light to any of a core of the first rare-earth-doped fiber and a core of the second rare-earth-doped fiber and inputs clad excitation light to a clad of the first rare-earth-doped fiber, the clad excitation light having a wavelength different from that of the core excitation light, and an optical filter that is arranged between the first rare-earth-doped fiber and the second rare-earth-doped fiber, and transmits the wavelength multiplexing optical signal and the core excitation light and blocks the clad excitation light.

A burst logging system logs and transmits to a local or remote computing system event data related to errors in and or potential failures of laser system components. The system further provides for capturing data at different rates from different sensors, synchronization of data capture associated with system events and the possibility for aggregation of data from multiple systems, which can in turn be leveraged to predict and or remediate future system events.