A nonlinear crystal including stacked strontium tetraborate SrB.sub.4O.sub.7 (SBO) crystal plates that are cooperatively configured to create a periodic structure for quasi-phase-matching (QPM) is used in the final frequency doubling stage of a laser assembly to generate laser output light having a wavelength in the range of about 180 nm to 200 nm. One or more fundamental laser beams are frequency doubled, down-converted and/or summed using one or more frequency conversion stages to generate an intermediate frequency light with a corresponding wavelength in the range of about 360 nm to 400 nm, and then the final frequency converting stage utilizes the nonlinear crystal to double the frequency of the intermediate frequency light to generate the desired laser output light at high power. Methods, inspection systems, lithography systems and cutting systems incorporating the laser assembly are also described.

A nonlinear crystal including stacked strontium tetraborate SrB.sub.4O.sub.7 (SBO) crystal plates that are cooperatively configured to create a periodic structure for quasi-phase-matching (QPM) is used in the final frequency doubling stage of a laser assembly to generate laser output light having a wavelength in the range of about 180 nm to 200 nm. One or more fundamental laser beams are frequency doubled, down-converted and/or summed using one or more frequency conversion stages to generate an intermediate frequency light with a corresponding wavelength in the range of about 360 nm to 400 nm, and then the final frequency converting stage utilizes the nonlinear crystal to double the frequency of the intermediate frequency light to generate the desired laser output light at high power. Methods, inspection systems, lithography systems and cutting systems incorporating the laser assembly are also described.

According to one embodiment, a nitride crystal includes first, second, and third nitride crystal regions. The third nitride crystal region includes Al, and is provided between the first and second nitride crystal regions. A third oxygen concentration in the third nitride crystal region is greater than a first oxygen concentration in the first nitride crystal region and greater than a second oxygen concentration in the second nitride crystal region. A third carbon concentration in the third nitride crystal region is greater than a first carbon concentration in the first nitride crystal region and greater than a second carbon concentration in the second nitride crystal region. A <0001> direction of the first nitride crystal region is one of a first orientation from the second nitride crystal region toward the first nitride crystal region or a second orientation from the first nitride crystal region toward the second nitride crystal region.

According to one embodiment, a nitride crystal includes first, second, and third nitride crystal regions. The third nitride crystal region includes Al, and is provided between the first and second nitride crystal regions. A third oxygen concentration in the third nitride crystal region is greater than a first oxygen concentration in the first nitride crystal region and greater than a second oxygen concentration in the second nitride crystal region. A third carbon concentration in the third nitride crystal region is greater than a first carbon concentration in the first nitride crystal region and greater than a second carbon concentration in the second nitride crystal region. A <0001> direction of the first nitride crystal region is one of a first orientation from the second nitride crystal region toward the first nitride crystal region or a second orientation from the first nitride crystal region toward the second nitride crystal region.

A solid-state laser system according to an aspect of the present disclosure includes a first non-linear crystal that generates first wavelength-converted light based on a first laser beam, a first adjustment unit configured to perform phase matching of the first wavelength-converted light in the first non-linear crystal, a second non-linear crystal that generates second wavelength-converted light based on a second laser beam and the first wavelength-converted light, a second adjustment unit configured to perform phase matching of the second wavelength-converted light in the second non-linear crystal, a light detection unit configured to detect light having a selected wavelength, and a processor configured to control the first adjustment unit based on intensity of at least one of the first wavelength-converted light and the first laser beam and to control the second adjustment unit based on intensity of at least one of the second wavelength-converted light and the first wavelength-converted light.

A solid-state laser system according to an aspect of the present disclosure includes a first non-linear crystal that generates first wavelength-converted light based on a first laser beam, a first adjustment unit configured to perform phase matching of the first wavelength-converted light in the first non-linear crystal, a second non-linear crystal that generates second wavelength-converted light based on a second laser beam and the first wavelength-converted light, a second adjustment unit configured to perform phase matching of the second wavelength-converted light in the second non-linear crystal, a light detection unit configured to detect light having a selected wavelength, and a processor configured to control the first adjustment unit based on intensity of at least one of the first wavelength-converted light and the first laser beam and to control the second adjustment unit based on intensity of at least one of the second wavelength-converted light and the first wavelength-converted light.

A solid-state laser system may include a first solid-state laser unit, a second solid-state laser unit, a wavelength conversion system, a wavelength detector, and a wavelength controller. The wavelength conversion system may receive a first pulsed laser light beam with a first wavelength and a second pulsed laser light beam with a second wavelength, and output a third pulsed laser light beam with a third wavelength converted from the first and second wavelengths. The wavelength controller may control the first solid-state laser unit to vary the first wavelength on a condition that an absolute value of a difference between a value of a target wavelength and a value of the third wavelength detected by the wavelength detector is equal to or less than a predetermined value, and control the second solid-state laser unit to vary the second wavelength on a condition that the absolute value exceeds the predetermined value.

A solid-state laser system may include a first solid-state laser unit, a second solid-state laser unit, a wavelength conversion system, a wavelength detector, and a wavelength controller. The wavelength conversion system may receive a first pulsed laser light beam with a first wavelength and a second pulsed laser light beam with a second wavelength, and output a third pulsed laser light beam with a third wavelength converted from the first and second wavelengths. The wavelength controller may control the first solid-state laser unit to vary the first wavelength on a condition that an absolute value of a difference between a value of a target wavelength and a value of the third wavelength detected by the wavelength detector is equal to or less than a predetermined value, and control the second solid-state laser unit to vary the second wavelength on a condition that the absolute value exceeds the predetermined value.

A harmonic light-generating metasurface includes a base substrate and a plurality of structures, that include nonlinear material, that are disposed in a pattern on a surface of the base substrate. Each structure of the plurality of structures individually supports a magnetic dipole mode. An electromagnetic field enhancement of the magnetic dipole mode induces generation of a harmonic signal by the plurality of structures. Alternatively, a harmonic light-generating metasurface, includes a base substrate, a supporting substrate that includes a nonlinear material, and a plurality of paired structures disposed in a pattern on a surface of the supporting substrate. Each paired structure, of the plurality of paired structures, collectively supports a toroidal dipole mode. An electromagnetic field enhancement of the toroidal dipole mode penetrates the supporting substrate to induce generation of a harmonic signal by the supporting substrate.

A harmonic light-generating metasurface includes a base substrate and a plurality of structures, that include nonlinear material, that are disposed in a pattern on a surface of the base substrate. Each structure of the plurality of structures individually supports a magnetic dipole mode. An electromagnetic field enhancement of the magnetic dipole mode induces generation of a harmonic signal by the plurality of structures. Alternatively, a harmonic light-generating metasurface, includes a base substrate, a supporting substrate that includes a nonlinear material, and a plurality of paired structures disposed in a pattern on a surface of the supporting substrate. Each paired structure, of the plurality of paired structures, collectively supports a toroidal dipole mode. An electromagnetic field enhancement of the toroidal dipole mode penetrates the supporting substrate to induce generation of a harmonic signal by the supporting substrate.