A method for operating a laser device (1), wherein an optical frequency comb can be stabilized and the frequencies of the modes thereof are describable by the formula f.sub.m=mf.sub.rep+f.sub.0, where f.sub.rep is a mode spacing, f.sub.0 is an offset frequency and m is a natural number. At least one signal (S1, S2, S3, S4) is determined, which correlates with an actual value of a degree of freedom (F), wherein the degree of freedom (F) is a linear combination of the offset frequency f.sub.0 and the mode spacing f.sub.rep of the frequency comb. The actual value of the degree of freedom (F) is set in a predetermined capture range (F) of a second control unit (40) using a first control unit (10) on the basis of the signal. As soon as the capture range (F.sub.capture) of the second control unit (40) is reached, the second control unit (40) is activated and the actual value is regulated to an intended value (F.sub.intended) with the aid of the second control unit (40).

A fingerprint sensor-compatible overlay material which uses anisotropic conductive material to enable accurate imaging of a fingerprint through an overlay is disclosed. The anisotropic conductive material has increased conductivity in a direction orthogonal to the fingerprint sensor, increasing the capacitive coupling of the fingerprint to the sensor surface, allowing the fingerprint sensor to accurately image the fingerprint through the overlay. Methods for forming a fingerprint sensor-compatible overlay are also disclosed.

Phase modulation of an output optical signal from a phase-sensitive amplifier may be used to perform phase adjustment for optimal phase-sensitive amplification. Specifically, when the optical pump is phase modulated to suppress SBS, a second phase modulator may be used to counter dither the first phase modulator. Both phase modulators may be controlled by a phase shifter. Intensity modulation of the output optical signal may also be performed to reduce noise. In this manner, the OSNR of the output optical signal may be increased.

An optical amplifier is provided which can suppress, without measuring signal beam power at individual wavelengths, wavelength-dependence of gain with respect to a signal beam into which multiple signal beams having respective wavelengths different from each other are multiplexed. The optical amplifier (100) according to the present invention can suppress wavelength-dependence of gain by giving loss in accordance with a linear-loss slope to an amplified signal beam. The optical amplifier is provided with a variable tilt equalizer (11) for varying a loss slope value representing the slope of the loss slope and a tilt control unit (22) for controlling a loss slope value of the variable tilt equalizer.

A laser apparatus includes a light source configured to output excitation light, an optical resonator in which laser medium. is excited by the excitation light, the optical resonator being configured to output laser beam, a temperature regulator configured to adjust temperature of the light source to a standard temperature, an optical detector configured to detect output power of the laser beam, and a controller configured to change the standard temperature based on the detected output power of the laser beam.

A speckle-free imaging light source based on a random fiber laser (RFL) using a strong-coupling multi-core optical fiber, relating to a field of optical fiber laser illumination light source, is provided, mainly including a pumping source and an optical fiber loop mirror, and further including the strong-coupling multi-core optical fiber with/without a single-mode optical fiber. Through directly adopting the strong-coupling multi-core optical fiber or combining the single-mode optical fiber with the strong-coupling multi-core optical fiber to serve as a main device in the RFL-based illumination light source, the generated RFL has multiple transvers modes and low spatial coherence which prevent speckle formation during illumination, which provides an ideal illumination light source for high-speed full-field speckle-free imaging technology.

The present invention relates to a device and a method for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb, and more particularly, to a device and a method for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb capable of stabilizing an overall range of frequencies of the femtosecond laser optical comb by using optical modes directly extracted from the optical comb and generating a cw laser and pulse having an excellent frequency stability and linewidth from the stabilized optical comb.

An optical power monitoring device detects an optical power propagating through an optical fiber including at least a core and a cladding. The optical power monitoring device includes: a first optical fiber; a second optical fiber having a larger core diameter than the first optical fiber; a connection part where an end surface of the first optical fiber and an end surface of the second optical fiber are spliced; a first leakage part for leakage of a beam from the first optical fiber to the outside; a second leakage part for leakage of a beam from the second optical fiber to the outside; a first photodetector that detects an optical power leaking from the first leakage part; and a second photodetector that detects an optical power leaking from the second leakage part.

A laser apparatus includes a plurality of laser modules, and includes a function for preventing a defect arising when switching the number of laser modules to be driven. The laser apparatus includes the plurality of laser modules, a combiner configured to combine laser beams from the plurality of laser modules, an optical output command section configured to generate a first optical output command for a combined laser beam, and a laser module selection/command section configured to select a laser module to be driven from the plurality of laser modules, based on the first optical output command and to generate a second optical output command for each of the laser modules that have been selected. The laser module selection/command section is configured to set a threshold value for a first optical output command to be different between when increasing and reducing the number of laser modules to be driven.

A laser apparatus including plural laser modules, and capable of preventing a defect occurring when a number of the modules to be driven is changed. The apparatus includes plural laser modules, an optical output command section for generating a first optical output command with respect to a combined laser beam from a combiner, and a laser module selection/command section for selecting a laser module to be driven and generating a second optical output command for each laser module. The laser module selection/command section outputs the second optical output command, in a period from when the number is changed to when a predetermined period of time elapses, to at least one of the laser modules that has been laser-oscillating before the number is changed, such that the combined laser beam having an output corresponding to the first optical output command is outputted only by the at least one laser module.