A supercontinuum radiation source comprises: a radiation source, an optical amplifier and a non-linear optical medium. The radiation source is operable to produce a pulsed radiation beam. The optical amplifier is configured to receive the pulsed radiation beam and increase an intensity of the pulsed radiation beam. The non-linear optical medium is configured to receive the amplified pulsed radiation beam and to broaden its spectrum so as to generate a supercontinuum radiation beam. The optical amplifier may supply a pump radiation beam to a gain medium, an intensity of the pump radiation beam being periodic and having a pump frequency that is an integer multiple of the frequency of the pulsed radiation beam. The optical amplifier may supply pump energy to a gain medium only when the pulses of the pulsed radiation beam propagate through the gain medium.

A microstructured optical fiber including a core region and a cladding region which surrounds the core region. The cladding region includes a plurality of cladding features within a cladding background material, wherein the cladding region includes an inner cladding region with at least one inner ring of cladding features and an outer cladding region with at least three outer cladding rings of outer cladding features. The inner cladding features have a first characteristic diameter and the outer cladding region includes a plurality of outer cladding features having a characteristic diameter smaller than the first characteristic diameter. The first characteristic diameter is at least about 10% larger than an average diameter of the outer cladding features and the core region has a diameter of at least about 2 ?m. A cascade optical fiber with at least one fiber as described, as well as a source of optical supercontinuum generation.

Provided are an optical fiber that has a short zero-dispersion wavelength, has high nonlinearity, and can cause broadband supercontinuum light to be generated with high efficiency, and a light source device that can output broadband supercontinuum light by using the optical fiber. A light source device includes a seed light source that outputs light with a central wavelength 1000 nm or more and 1650 nm or less and an optical fiber that receives the light output from the seed light source, allows the light to propagate therethrough, causes broadband light with an expanded band to be generated in accordance with a nonlinear optical phenomenon while the light propagates therethrough, and outputs the broadband light. The optical fiber is composed of silica glass, has a zero-dispersion wavelength of 1290 nm to 1350 nm, and has an effective area of 14 m.sup.2 or smaller at a wavelength of 1550 nm.

A broadband light source device (100) for creating broadband light pulses (1) comprises a hollow-core fiber (10) of non-bandgap type including a filling gas and being arranged for creating the broadband light pulses (1) by an optical nonlinear broadening of pump laser pulses (2), wherein the hollow-core fiber (10) has an axial hollow light guiding fiber core (11), which supports core modes of a guided light field, and an inner fiber structure (12), which surrounds the fiber core (11) and which supports transverse wall modes of the guided light field, and a pump laser source device (20) being arranged for creating and providing the pump laser pulses (2) at an input side (13) of the hollow-core fiber (10), wherein the transverse wall modes include a fundamental transverse wall mode and second and higher order transverse wall modes, the broadband light pulses (1) have a core mode spectrum being determined by a fiber length, a fiber core diameter, at least one pump pulse and/or beam parameter of the pump laser pulses (2) and at least one gas parameter of the filling gas, and the inner fiber structure (12) of the hollow-core fiber (10) is configured such that at least the second and higher order transverse wall modes and the core mode spectrum have a spectral displacement relative to each other. Furthermore, a method of creating broadband light pulses is described.

A system for modulating a terahertz beam includes a multiferroic nanoparticle heterostructure through which a terahertz beam can be propagated, and means for applying an external direct current (DC) magnetic field to the multiferroic nanoparticle heterostructure and the terahertz beam propagating through it, wherein application of the DC magnetic field modulates one or both of an amplitude and a phase of the terahertz beam.

A supercontinuum light source can include a seed laser arranged to provide seed pulses with a pulse frequency F.sub.seed; a pulse frequency multiplier (PFM) arranged to multiply the seed pulses by converting pulses having the pulse frequency F.sub.seed to pump pulses with a pulse frequency F.sub.pump, where F.sub.pump is larger than F.sub.seed; and a non-linear element arranged to receive said pump pulses and convert said pump pulses to pulses of supercontinuum light. The PFM can further include a splitter for splitting pulses into first and second sub beams each having the same pulse frequency, where the PFM is configured such that the sub beams experience different delays; and a combiner for combining said first and second sub beams into a beam having the pulse frequency that is greater than said same pulse frequency. The splitter can have an uneven splitter ratio. The disclosure includes other embodiments as well.

A supercontinuum radiation source for an alignment mark measurement system comprises: a radiation source; illumination optics; a plurality of waveguides; and collection optics. The radiation source is operable to produce a pulsed radiation beam. The illumination optics is arranged to receive the pulsed pump radiation beam and to form a plurality of pulsed sub-beams, each pulsed sub-beam comprising a portion of the pulsed radiation beam. Each of the plurality of waveguides is arranged to receive at least one of the plurality of pulsed sub-beams beam and to broaden a spectrum of that pulsed sub-beam so as to generate a supercontinuum sub-beam. The collection optics is arranged to receive the supercontinuum sub-beam from each of the plurality of waveguides and to combine them so as to form a supercontinuum radiation beam.

A multiple wavelength light source device and associated method for generating output radiation that has a plurality of discrete output wavelength bands. The multiple wavelength light source device includes a pump radiation source arrangement configured to generate input radiation including at least a first frequency component and a second frequency component; and a hollow-core photonic crystal fiber configured to confine a working medium. The hollow-core photonic crystal fiber is configured to receive the input radiation and to generate the plurality of discrete output wavelength bands distributed over a wavelength range of interest via a seed-assisted cascaded four wave mixing (FWM) process in the working medium.

A supercontinuum radiation source comprises: a radiation source, an optical amplifier and a non-linear optical medium. The radiation source is operable to produce a pulsed radiation beam. The optical amplifier is configured to receive the pulsed radiation beam and increase an intensity of the pulsed radiation beam. The non-linear optical medium is configured to receive the amplified pulsed radiation beam and to broaden its spectrum so as to generate a supercontinuum radiation beam. The optical amplifier may supply a pump radiation beam to a gain medium, an intensity of the pump radiation beam being periodic and having a pump frequency that is an integer multiple of the frequency of the pulsed radiation beam. The optical amplifier may supply pump energy to a gain medium only when the pulses of the pulsed radiation beam propagate through the gain medium.

A holographic observation method includes: casting a light beam generated by driving a semiconductor laser light source with an electric current with an alternating-current component superimposed or a light beam having a predetermined spectral width and predetermined spectral intensity to have predetermined coherency to an observation object; forming a hologram by causing a light beam transmitted through or reflected by the observation object to interfere with a reference light beam; and obtaining information on the observation object by performing image processing on the hologram.