A device for generating laser radiation comprises a temperature-controlled optical setup comprising an optically non-linear solid state medium arranged in a resonator and an active region. The outgoing laser radiation is generated from a pump beam introduced into the optically non-linear solid state medium. A first temperature actuator and a second temperature actuator configured to independently adjust temperature values in the active region of the optically non-linear solid state medium. The first temperature actuator is configured regulate a length of the resonator by setting a first temperature value within a first portion of the active region. The second temperature actuator is configured to match phases of wavelengths generated by the outgoing laser radiation and phases of wavelengths of the pump beam radiation by setting a second temperature value within a second portion of the active region.

This invention provides a device for improving laser wavelength conversion efficiency and a laser system configured to provide high-power multi-wavelength femtosecond laser pulses using the device. The device for improving laser wavelength conversion efficiency comprises a wavelength conversion member photonic crystal fiber (PCF), wherein the device for improving laser wavelength conversion efficiency improves wavelength conversion efficiency by shortening the length of the PCF. The device provided in this invention not only reduces the attenuation and dispersion caused by the optical fiber, but also improves the energy conversion efficiency within a specific wavelength range. The use of the technique not only increases the energy of light pulse, but also greatly reduces the amount of fiber used, and can maximize the energy of the desired wavelength according to experimental requirements when using laser input sources of different wavelengths.

In a general aspect, quantum electrodynamic (QED) interactions are generated using a parabolic transmission mirror. In some aspects, a system for generating a QED interaction includes an optical pulse generator and a vacuum chamber. The vacuum chamber includes a parabolic transmission mirror in an ultra-high vacuum region within the vacuum chamber. The parabolic transmission mirror is configured to produce the QED interaction in the ultra-high vacuum region based on an optical pulse from the optical pulse generator. The parabolic transmission mirror includes an optical inlet at a first end and an optical outlet at a second, opposite end. The parabolic transmission mirror also includes a parabolic reflective surface about an internal volume of the parabolic transmission mirror between the first and second ends. The parabolic reflective surface extends from the optical inlet to the optical outlet and defines a focal point outside the internal volume of the parabolic transmission mirror.

A mode control system and method for controlling an output mode of a broadband radiation source including a photonic crystal fiber (PCF). The mode control system includes at least one detection unit configured to measure one or more parameters of radiation emitted from the broadband radiation source to generate measurement data, and a processing unit configured to evaluate mode purity of the radiation emitted from the broadband radiation source, from the measurement data. Based on the evaluation, the mode control system is configured to generate a control signal for optimization of one or more pump coupling conditions of the broadband radiation source. The one or more pump coupling conditions relate to the coupling of a pump laser beam with respect to a fiber core of the photonic crystal fiber.

A dispersion measurement apparatus includes a pulse forming unit, a correlation optical system, a photodetection unit, and an operation unit. The pulse forming unit forms a light pulse train including a plurality of light pulses having time differences and center wavelengths different from each other from a measurement target light pulse output from a pulsed laser light source. The correlation optical system receives the light pulse train output from the pulse forming unit and outputs correlation light including a cross-correlation or an autocorrelation of the light pulse train. The photodetection unit detects a temporal waveform of the correlation light output from the correlation optical system. The operation unit estimates a wavelength dispersion amount of the pulsed laser light source based on a feature value of the temporal waveform of the correlation light.

Disclosed are ideas to produce an add-on device which turns widely used high repetition rate lasers used for 2-photon microscopy into a light source which can be used for 3-photon microscopy. The add-on encompasses a device to reduce the pulse repetition rate of the high repetition rate (>50 MHz) laser source (laser or OPO) to less than 10 MHz which allows for higher pulse energies while maintaining reasonable average powers. If the high repetition sources operate below 1250 nm the add-on shifts or broadens the seed light to cover 1.3 μm to 1.8 μm before amplification. If the high repetition rate source operates at or around 1.3 μm the add-on only needs to amplify the pulse after downshifting the repetition rate. In another implementation the add-on shifts or broadens the 1.3 μm light to cover the spectral range out to 1.8 μm before amplification.

Disclosed by the present invention is an ultra-wideband white noise source based on a slicing super-continuum spectrum. The entropy source used is a super-continuum spectrum photon entropy source having a coverage range of several hundreds of nm, white noise can thus be generated in a wide frequency range, thereby effectively avoiding the bandwidth bottleneck of an electronic device. By separately adjusting the filter centers of two optical filters, the center frequency for generating the white noise can be adjusted so as to get adapted to different working situations. High bandwidth white noise can be generated by simply filtering the super-continuum spectrum and performing photoelectric conversion, and in comparison with the previous solutions, the solution of the present invention is simpler and can be easily implemented.

A cylindrical electrode module of a fiber optic laser system includes an inner cylinder having an inner repeating pattern of longitudinally-aligned positive and negative electrodes on an outer surface of the inner cylinder. The cylindrical electrode mode includes an outer cylinder that encloses the inner cylinder. The outer cylinder that has an outer repeating pattern of longitudinally-aligned negative and positive electrodes on an inner surface of the inner cylinder that are in corresponding and complementary, parallel alignment with the positive and negative electrodes of the inner repeating pattern on the outer surface of the inner cylinder. The cylindrical electrode module includes an optical fiber having an input end configured to align with and be optically coupled to a pump laser. The optical fiber is wrapped around the inner cylinder within the outer cylinder to form a cylindrical fiber assembly. The electrodes are activated to achieve quasi-phase matching.

A nonlinear crystal comprising a first end face and an opposing second end face is described. The first and second end faces are separated along an optical axis of the nonlinear crystal by a length in the range of 0.25 mm and 2 mm. Although the length of the nonlinear crystal results in a reduction in the nonlinear effects induced on an optical field propagating through the crystal it also provides for reduced deviation experienced by the generated optical field when the nonlinear crystal is rotated. Therefore, when the nonlinear crystals are incorporated within an enhancement cavity their reduced length allows for the deviation of the output field to be minimised by servo control electronics arranged to adjust a single cavity mirror. This significantly reduces the complexity, and thus expensive of the servo control electronics when compared to those employed with the prior art enhancement cavities.

An illumination source apparatus (500), suitable for use in a metrology apparatus for the characterization of a structure on a substrate, the illumination source apparatus comprising: a high harmonic generation, HHG, medium (502); a pump radiation source (506) operable to emit a beam of pump radiation (508); and adjustable transformation optics (510) configured to adjustably transform the transverse spatial profile of the beam of pump radiation to produce a transformed beam (518) such that relative to the centre axis of the transformed beam, a central region of the transformed beam has substantially zero intensity and an outer region which is radially outwards from the centre axis of the transformed beam has a non-zero intensity, wherein the transformed beam is arranged to excite the HHG medium so as to generate high harmonic radiation (540), wherein the location of said outer region is dependent on an adjustment setting of the adjustable transformation optics.