A control system includes a field-programmable gate array (FPGA), a digital-to-analog conversion (DAC) circuit, an external TEC driver, and a pump chip. The field-programmable gate array (FPGA) includes a pump driver and a thermoelectric-cooler (TEC) controller. The digital-to-analog conversion (DAC) circuit is coupled to the FPGA. The external TEC driver is external to the FPGA and coupled to the FPGA. The pump chip includes a pump and a TEC and is coupled to the DAC circuit and the external TEC driver.

Provided are a method and system for controlling a Raman fiber amplifier. The method comprises: according to a target gain and a tilt, calculating an expected output power of a pump by using a feedforward formula, and obtaining an actual output power of the pump through detection (201); locking the actual output power of the pump to the expected output power through first-stage feedback control (202); according to the target gain and the tilt, calculating an expected ASE power of the pump by using an ASE formula, and obtaining an actual out-of-band ASE power of the pump through detection (203); if the out-of-band ASE is not locked, determining gain compensation and tilt compensation of the pump through second-stage feedback control, and feeding the compensation back to the feedforward formula and the ASE formula for recalculation (204); and repeatedly performing the first-stage feedback control and the second-stage feedback control until the gain and the tilt are locked (205). In the system, a combination of feedforward and multi-closed loop feedback control is used to realize rapid locking of a pump power and locking of the gain and the tilt compensation, which improves the control precision of the gain and the tilt and accelerates a response speed.

This application discloses an optical amplifier including a Raman fiber amplifier (RFA), a dynamic gain equalizer (DGE), a filter, an erbium-doped fiber amplifier (EDFA), an RFA gain controller, an EDFA gain controller, and an optical amplifier controller. The optical amplifier controller is configured to provide instructions to and receive feedback from the RFA and EDFA gain controllers. The RFA and the EDFA are configured to amplify an optical signal. The RFA gain controller is configured to control the RFA to adjust a gain. The EDFA gain controller is configured to control the EDFA to adjust a gain. The DGE adjusts insertion loss. The filter is configured to filter an amplified spontaneous emission signal produced in an optical amplification process of the RFA.

An amplification fiber includes a core which is doped with an erbium ion and a cladding which surrounds the core and has a refractive index lower than a refractive index of the core, and a relative refractive index difference Δn.sub.51 between the core and the cladding is not more than a smaller one of values of a relative refractive index difference Δn.sub.1 expressed as a predetermined expression related to a radius a of the core and a relative refractive index difference Δn.sub.2 expressed as a predetermined expression related to the radius a of the core.

In a laser system according to a viewpoint of the present disclosure, a first amplifier amplifies first pulsed laser light outputted from a first semiconductor laser system into second pulsed laser light, a wavelength conversion system converts the second pulsed laser light in terms of wavelength into third pulsed laser light, and an excimer amplifier amplifies the third pulsed laser light. The first semiconductor laser system includes a first current controller that controls current flowing through a first semiconductor laser in such a way that first laser light outputted from the first semiconductor laser is caused to undergo chirping and a first semiconductor optical amplifier that amplifies the first laser light into pulsed light. The laser system includes a control section that controls the amount of chirping performed on the first pulsed laser light in such a way that excimer laser light having a target spectral linewidth is achieved.

A low-noise amplifier includes a gain medium and two or more amplifier stages. Each amplifier stage includes an optical filter to pass all wavelengths of a respective input optical signal in a given propagation direction over the gain medium and reflect wavelengths above a respective threshold wavelength received in the opposite direction, and a respective Raman pump to inject a pump light centered at a wavelength lower than the threshold wavelength onto the gain medium for transmission in the given direction. A first amplifier stage outputs a first combined optical signal including all wavelengths of the respective input optical signal and a pump light injected by the respective Raman pump. The second amplifier stage receives the first combined optical signal as its input and outputs a second combined optical signal including all wavelengths of the first combined optical signal and a pump light injected by the respective Raman pump.

The present invention relates to a device for generating laser radiation.

A problem addressed by the present invention is that of specifying a device for generating laser radiation using a nonlinear crystal, which device has a simple construction and low optical losses.

The device according to the invention comprises an optical amplifier having an active zone, wherein the optical amplifier has a front facet and a rear facet, between which the active zone extends; and a resonator having a first resonator element and a second resonator element, between which the optical amplifier extends, wherein the first resonator element is arranged on a side of the active zone facing away from the front facet and the second resonator element is arranged on a side of the active zone facing the front facet, and wherein the second resonator element comprises a nonlinear crystal having periodic poling.

A laser light-source apparatus includes a seed light source 10, fiber amplifiers 20 and 30 and a solid state amplifier 50 configured to amplify pulse light output from the seed light source, nonlinear optical elements 60 and 70 configured to perform wavelength conversion on the pulse light output from the solid state amplifier 50 and output the resultant pulse light, a semiconductor optical amplifier 15 disposed between the seed light source 10 and the solid state amplifier 50 and configured to amplify the pulse light output from the seed light source 10, and a control unit 100 configured to execute gain switching control processing in which the seed light source 10 is driven at a desired pulse rate, and semiconductor optical amplifier control processing in which an injection current to the semiconductor optical amplifier 15 is controlled depending on the pulse rate of the seed light source 10, and thus, generation of a giant pulse can be reliably prevented, regardless of the pulse rate of the seed light source.

A method of reducing the power consumption of an optical fiber amplifier by which the optical output of a first optical fiber is filtered to prevent a detrimental portion of the optical output from reaching a second optical fiber, to transmit a signal for amplification, and to transmit a portion of the optical output that can contribute to optical pumping of the second optical fiber. By propagating an optical pumping portion output from the first optical fiber, as well as optical pumping from an independent source, the independent source's power level can be reduced. In a sequence of optical fibers, each fiber can provide some pumping output to one or more other fibers, as long as its optical output is properly filtered with appropriate optical components, such as a band-stop filter. A sequence can be terminated by a low-pass filter in order for a final output to contain the amplified signal free from any other optical output.

An optical amplifier comprises a gain medium having an input surface and an output surface wherein the output surface is larger than the input surface. The gain medium may be frustum shaped. The optical amplifier includes a negative diverging lens to receive an extraction laser beam and to cause the laser beam to expand as the beam passes through the gain medium. The amplifier further comprises a positive collimating lens configured to receive the expanding amplified beam and reduce the divergence. The gain medium can be pumped by counter-propagating radiation. The fluence of the laser beam within the gain medium is configured to be near constant along the length of the gain medium and may be within 1.5-2.0 F.sub.SAT. The gain medium may be doped with dopant to provide gain, with larger concentration of dopants proximal the input surface and smaller concentration proximal the output surface.