Abstract: Apparatus for monitoring the output of an optical system. The apparatus comprises first and second fibre optic sections, a reflective coating, and a detector. The first fibre optic section has a first cladding and a first core, and is configured to receive light from the optical system at one end and has at the other end a first angled, polished face. The second fibre optic section has a second cladding and a second core, and has at one end a second angled, polished face. The first and second fibre optic sections are arranged such that the first and second angled, polished faces are substantially parallel and adjacent and the first and second cores are substantially aligned. The reflective coating is applied to the first or second angled, polished face, and is configured to reflect a portion of light transmitted through the first core. The detector is arranged to receive the reflected light.

Abstract: Embodiments of the present disclosure provide etch-variation tolerant optical coupling components and processes for making the same. An etch-variation tolerant geometry is determined for at least one waveguide of an optical coupling component (e.g., a directional coupler). The geometry is optimized such that each fabricated instance of an optical component design with the etch-variation tolerant geometry has substantially the same coupling ratio at any etch depth between a shallow etch depth and a deep etch depth.

Abstract: A method (100) of encoding communications traffic bits onto an optical carrier signal in a pulse amplitude modulation, PAM, format. The method comprises: receiving (102) bits to be transmitted; receiving (104) an optical carrier signal comprising optical pulses having an amplitude and respective phases; performing (106) PAM of the optical pulses to encode at least one respective bit in one of a pre-set plurality of amplitudes of a said optical pulse; and performing (108) phase modulation of the optical pulses to encode at least one further respective bit in a phase difference between a said optical pulse and a consecutive optical pulse.

Abstract: Examples of diffractive devices comprise a cholesteric liquid crystal (CLC) layer comprising a plurality of chiral structures, wherein each chiral structure comprises a plurality of liquid crystal molecules that extend in a layer depth direction by at least a helical pitch and are successively rotated in a first rotation direction. Arrangements of the liquid crystal molecules of the chiral structures vary periodically in a lateral direction perpendicular to the layer depth direction to provide a diffraction grating. The diffractive devices can be configured to reflect light having a particular wavelength range and sense of circular polarization. The diffractive devices can be used in waveguides and imaging systems in augmented or virtual reality systems.

Abstract: An apparatus and method for calculating the frequency of the light.

Abstract: Aspects of the present disclosure describe optical phased array structures and devices in which hyperbolic phase envelopes are employed to create focusing and diverging emissions in one and two dimensions. Tuning the phase fronts moves focal point spot in depth and across the array. Grating emitters are also used to emit light upward (out of plane). Adjusting the period of the gratings along the light propagation direction results in focusing the light emitted from the gratings. Changes in the operating wavelengths employed moves the focal spot along the emitters.

Abstract: A device includes a first and a second part, relatively rotatable, and data transmission structures for contactless transmission of data. The data transmission structures include a transmit and/or receive facility a coupling facility on the two parts. The transmit and/or receive facility extends over a small angle and the coupling facility extends over a complete circle. Data is transmitted between the facilities at a transmission frequency. The two parts include walls encompassing a tunnel interior space extending completely around the axis of rotation. The data transmission structures are arranged in the tunnel interior space. The walls are electrically conductive structures reflecting electromagnetic alternating fields in the transmission frequency range. An absorber structure is arranged at least on a part of the walls toward the tunnel interior space and the absorber structure absorbs electromagnetic alternating fields in the range of the transmission frequency.

Abstract: A method for chromatic dispersion pre-compensation in an optical communication network includes (1) distorting an original modulated signal according to an inverse of a transmission function of the optical communication network, to generate a compensated signal, (2) modulating a magnitude of an optical signal in response to a magnitude of the compensated signal, and (3) modulating a phase of the optical signal, after modulating the magnitude of the optical signal, in response to a phase of the compensated signal.

Abstract: An optical sensor system may include a light source. The optical sensor system may include a concentrator component proximate to the light source and configured to concentrate light from the light source with respect to a measurement target. The optical sensor system may include a collection component that includes an array of at least two components configured to receive light reflected or transmitted from the measurement target. The optical sensor system may include may a sensor. The optical sensor system may include a filter provided between the collection component and the sensor.

Abstract: Optical telecommunication receivers and transmitters are described comprising dispersive elements and adjustable beam steering elements that are combined to provide optical grid tracking to adjust with very low power consumption to variations in the optical grid due to various changes, such as temperature fluctuations, age or other environmental or design changes. Thus, high bandwidth transmitters or receivers can be provides with low power consumption and/or low cost designs.

Abstract: A system for monitoring a signal on an optical fiber includes a fiber optic connector having a housing couplable to a receptacle. An optical fiber that transmits a first optical signal has first fiber core at least partially surrounded by a cladding and has a first end terminating proximate the housing. The first optical signal is transmitted along the first fiber core. An optical tap has a first tap waveguide arranged and is configured to receive at least part of the first optical signal as a first tap signal. The first tap waveguide comprises an output port for the first tap signal for directing the tap signal to a detector unit. In other embodiments, a detector unit detects light from the optical signal that is propagating along the fiber cladding.

Abstract: An approach for realizing low-power, high-port-count optical switching systems, such as OXCs, WXCs, and ROADMs is presented. Optical switching systems in accordance with the present disclosure include arrangements of frequency-filter blocks, each of which includes a cascaded arrangement of tunable couplers and tunable Mach-Zehnder Interferometers (MZIs) that provides a substantially flat-top broadband transfer function for the frequency-filter block. The tunability for these devices is achieved by operatively coupling a low-power-dissipation phase controller, such as a stress-optic phase controller or liquid-crystal-based phase controller with one arm of the device, thereby enabling control over the coupling coefficient of the device.

Abstract: A figure-8 laser is configured in which gain in the uni-directional loop can be removed while maintaining mode-locked operation with gain only in the bi-directional nonlinear amplifying loop. Simplified self-starting and control over pulse characteristics by controlling gain in the bi-directional loop is made possible.

Abstract: Aspects described herein include an optical apparatus comprising an input port configured to receive an optical signal comprising a plurality of wavelengths, and a plurality of output ports. Each output port is configured to output a respective wavelength of the plurality of wavelengths. The optical apparatus further comprises a first plurality of two-mode Bragg gratings in a cascaded arrangement. Each grating of the first plurality of two-mode Bragg gratings is configured to reflect a respective wavelength of the plurality of wavelengths toward a respective output port of the plurality of output ports, and transmit any remaining wavelengths of the plurality of wavelengths.

Abstract: In a general aspect, a photonic crystal maser includes a dielectric body having an array of cavities ordered periodically to define a photonic crystal structure in the dielectric body. The dielectric body also includes a region in the array of cavities defining a defect in the photonic crystal structure. An elongated slot through the region extends from a slot opening in a surface of the dielectric body at least partially through the dielectric body. The elongated slot and the array of cavities define a waveguide of the dielectric body. The dielectric body additionally includes an input coupler aligned with an end of the elongated slot and configured to couple a reference radiofrequency (RF) electromagnetic radiation to the waveguide. The photonic crystal maser also includes a vapor or source of the vapor in the elongated slot and an optical window covering the elongated slot.

Abstract: A display waveguide configured for conveying image light to a viewer has a waveguide body whose refractive index varies in the thickness direction to include a high-index region between lower-index regions. Multi-layer and gradient index implementations are described. The waveguide transmits a portion of image light within the high-index region of the waveguide to provide a wider field of view.

Abstract: A wavelength demultiplexing device configured so as to spatially distributing the spectral contributions of an incident light beam, when in use, and which includes a linear waveguide and a planar waveguide, formed in a coplanar way and adapted to be optically coupled with one another along a coupling line, by evanescent coupling. Such a device may further include diffraction gratings located in the planar waveguide, to extract light out of the latter.

Abstract: Disclosed is a frequency swept source apparatus including a mode locking laser that outputs an input optical signal having first to n-th frequency components, a transmission delay controller that generates first to m-th sub-optical signals, each of which includes at least one component of the first to n-th frequency components, and outputs a delay optical signal obtained by sequentially delaying the first to m-th sub-optical signals. The transmission delay controller includes a demultiplexer that outputs the first to m-th sub-optical signals to first to m-th channels based on the input optical signal, respectively, a path delay unit that adjusts lengths of optical paths of the first to m-th channels so as to be different from one another, a refractive index controller that adjusts a refractive index of each of the first to m-th channels, and a multiplexer that combines the first to m-th sub-optical signals.

Abstract: An optical device includes a first semiconductor substrate, a reference laser configured to generate coherent light, a plurality of first optical components, a plurality of second optical components, one or more first controllers configured to apply phase control signals to said plurality of first optical components to apply a phase shift, and one or more second controllers configured to apply pulse control signals to said plurality of second optical components such that a light pulse is outputted during a period of time that coherent light is received. The relative phase between emitted light pulses from the plurality of second optical components is controlled by the relative phase shifts applied by the one or more first controllers.

Abstract: A parallel optical fiber angled coupling component, which is used for parallel coupling of optical signal between the optical fiber array and the laser array, comprises an optical fiber positioning substrate, a cover plate and a plurality of optical fibers. The end face of the optical fiber is polished into a bevel with an inclination of 42.5° or 47.5°, and the bevel of the optical fiber is coated with a metal reflective film. This invention has the following beneficial effects: The end face of the optical fiber is polished into a bevel with an inclination of 42.5° or 47.5° to reduce inter-modal dispersion and increase the transmission distance of the optical signal in the subsequent optical fiber; the bevel of the optical fiber is coated with a metal reflective film, so as to ensure high reflectivity even if the bevel of the optical fiber is covered with glue.

Abstract: A biological information measurement apparatus comprises: a light source which illuminates a measurement target with light; a light receiving portion which receives a light amount of reflected light of the light from the measurement target; and a selecting unit which, based on a light amount received by the light receiving portion at each of a plurality of wavelengths of the reflected light, selects a wavelength to be used to measure biological information from the plurality of wavelengths.

Abstract: A link extender configured to extend a range of an optical transceiver module is provided. The link extender includes an array of semiconductor optical amplifiers (SOAs) configured to amplify an optical signal received from the optical transceiver module, a first plurality of variable optical attenuators (VOAs) configured to control a power output of the amplified optical signal output from the array of SOAs, and a plurality of dispersion compensation and filtering (DC&F) devices configured to compensate for chromatic dispersion of the optical signal.

Abstract: A wavelength converting material includes a luminous core and a first protective layer. The first protective layer covers the luminous core, in which the first protective layer includes silicon dioxide, and in silicon atoms of the silicon dioxide, the silicon atom of the zeroth configuration (Q0) does not connect with any siloxy group, and the silicon atom of the first configuration (Q1) connects with one siloxy group, and the silicon atom of the second configuration (Q2) connects with two siloxy groups, and the silicon atom of the third configuration (Q3) connects with three siloxy groups, and the silicon atom of the fourth configuration (Q4) connects with four siloxy groups, in which a total amount of the silicon atoms of the third configuration and the fourth configuration is greater than a total amount of the silicon atoms of the zeroth configuration, the first configuration and the second configuration.

Abstract: A mirror system including a primary mirror, and a secondary mirror with different coefficients of thermal expansion. A negative CTE strut can include a main body portion, a first coupling portion and a second coupling portion disposed opposite one another about the main body portion and defining a strut length. The first and second coupling portions can each interface with an external structure. The negative CTE strut can include an offsetting extension member having a first end coupled to the main body portion and a second end coupled to the first coupling portion by an intermediate extension member. The first and second ends can define an offset length parallel to the strut length. When the negative CTE strut increases in temperature, the offset length can be configured to increase due to thermal expansion of the offsetting extension member sufficient to cause the strut length to decrease.

Abstract: An optical switch includes a bus waveguide and an optical antenna supported by a substrate, a first and second coupling waveguide, a first and second actuation electrode, and a first and second reaction electrode. The first coupling waveguide is disposed parallel with the substrate and aligned with the bus waveguide. The first reaction electrode is coupled with, and adjacent to, the first coupling waveguide. The second coupling waveguide is optically connected with the first coupling waveguide and suspended over and configured to optically couple with the optical antenna. The second reaction electrode is coupled with, and adjacent to, the second coupling waveguide. The first and second actuation electrodes are supported by the substrate and configured to control the position of the first and second coupling waveguide, respectively, relative to the bus waveguide and optical antenna, via the first and second reaction electrodes.

Abstract: An optical switch includes a bus waveguide supported by a substrate, a coupling waveguide suspended over the bus waveguide, a reaction electrode coupled with, and adjacent to, the coupling waveguide, an actuation electrode supported by the substrate and configured to control a position of the coupling waveguide relative to the bus waveguide via the reaction electrode, and an optical antenna coupled with the coupling waveguide and disposed at a fixed distance from the bus waveguide. When a voltage difference between the reaction electrode and the actuation electrode is less than a lower threshold, the coupling waveguide is positioned a first distance from the bus waveguide, when the voltage difference between the reaction electrode and the actuation electrode is greater than an upper threshold, the coupling waveguide is positioned a second distance from the bus waveguide, and the second distance is less than the first distance.

Abstract: An optical circuit includes: a multicast-and-select (MCS) switch and multiple optical selective devices coupled to output ports of the MCS switch. The selective devices may select a single optical channel by blocking some of wavelengths of light passing therethrough and passing at least one other wavelength. The selective devices may be wave blockers or tunable optical filters. The optical circuit further includes an optical amplifying array, wherein each amplifier has an input port optically coupled to one of the selective devices. At least some of the amplifiers have pump light ports for receiving at least a portion of the pump light from one or more laser pumps or from another of the optical amplifiers, wherein the pumps are capable of providing pump light sufficient to fully saturate all of the rare earth doped optical fibers in the array.

Abstract: An improved waveguide is disclosed. The waveguide utilizes a luminescent material disposed within or around its perimeter to introduce additional light into the waveguide. For example, the waveguide may include a plurality of planar layers having different refractive indexes. A luminescent material may be disposed along the outer edge of these layers. When light from within the waveguide strikes the luminescent material, it emits light, thereby adding to the light in the waveguide. Not only does the luminescent material introduce more light into the waveguide, it also introduces more light sources, thereby making it more difficult to introduce a probe without blocking at least a portion of the light destined for the image sensor. The luminescent material may be a phosphor.

Abstract: Examples of diffractive devices comprise a cholesteric liquid crystal (CLC) layer comprising a plurality of chiral structures, wherein each chiral structure comprises a plurality of liquid crystal molecules that extend in a layer depth direction by at least a helical pitch and are successively rotated in a first rotation direction. Arrangements of the liquid crystal molecules of the chiral structures vary periodically in a lateral direction perpendicular to the layer depth direction to provide a diffraction grating. The diffractive devices can be configured to reflect light having a particular wavelength range and sense of circular polarization. The diffractive devices can be used in waveguides and imaging systems in augmented or virtual reality systems.

Abstract: A semiconductor photomultiplier includes a microcell, a photosensitive diode, and an anti-reflective coating. The microcell has an insulating layer formed over an active region. The photosensitive diode is formed in the active region beneath the insulating layer. The anti-reflective coating is provided on the insulating layer.

Abstract: An optical waveguide structure has a waveguide core including an inner and an outer layer with different refractive indices, and a refractive index ratio of the different refractive indices is greater than or equal to 1.15. A dispersion controlling method using the optical waveguide structure includes: first, obtaining a dispersion curve having up to 5 zero-dispersion wavelengths by calculating based on a set of preset structural size parameters of the optical waveguide; and then, adjusting one or more of the width (W) of a contact surface between the inner layer and the substrate, the thickness (H) of a higher refractive index material, and the thickness (C) of a lower refractive index material, so as to implement dispersion control.

Abstract: Systems and methods for performing coherent diffraction in an optical device are disclosed. An optical device may include a grating medium with a first hologram having a first grating frequency. A second hologram at least partially overlapping the first hologram may be provided in the grating medium. The second hologram may have a second grating frequency that is different from the first grating frequency. The first and second holograms may be pair-wise coherent with each other. A manufacturing system may be provided that writes the pair-wise coherent holograms in a grating medium using a signal beam and a reference beam. Periscopes may redirect portions of the signal and reference beams towards a partial reflector, which combines the beams and provides the combined beam to a detector. A controller may adjust an effective path length difference between the signal and reference beams based on a measured interference pattern.

Abstract: Compact optical spectrometers are provided to measure optical spectral composition of light.

Abstract: A bidirectional optical repeater having two unidirectional optical amplifiers and a supervisory optical circuit connected to optically couple the corresponding two optical paths through the repeater. In an example embodiment, the supervisory optical circuit is symmetrical in the sense that it enables the two optical input/output port pairs of the repeater to be interchangeable and functionally equivalent at least with respect to two supervisory wavelengths and some in-band and/or out-of-band wavelengths. This symmetry can advantageously be used, e.g., to improve the installation process directed at installing such optical repeaters in an undersea cable system. For example, a single directional orientation of the optical repeaters does not need to be maintained throughout the cable system, which can significantly reduce the risk and/or cost of installation errors.

Abstract: Disclosed herein is an integrated photonics device including a frequency stabilization subsystem for monitoring and/or adjusting the wavelength of light emitted by one or more light sources. The device can include one or more selectors that can combine, select, and/or filter light along one or more light paths, which can include light emitted by a plurality of light sources. Example selectors may include, but are not limited to, an arrayed waveguide grating (AWG), a ring resonator, a plurality of distributed Bragg reflectors (DBRs), a plurality of filters, and the like. Output light paths from the selector(s) can be input into one or more detector(s). The detector(s) can receive the light along the light paths and can generate one or more signals as output signal(s) from the frequency stabilization subsystem.

Abstract: An optical coupler comprises an adiabatic waveguide structure having a proximal end and a distal end, with the adiabatic waveguide structure comprising: a first waveguide comprising an input section at the proximal end; a first coupling section contiguous with the input section and extending toward the distal end; and a first laterally displaced section contiguous with the first coupling section. The first waveguide narrows along the first coupling section, from the input section to the first laterally displaced section. A second waveguide is separate from the first waveguide and comprises a second laterally displaced section adjacent to the proximal end; a second coupling section contiguous with the second laterally displaced section and extending toward the distal end; and an output section contiguous with the second coupling section. The second waveguide widens along the second coupling section, from the second laterally displaced section to the output section.

Abstract: An optical dispersion compensator integrated with a silicon photonics system including a first phase-shifter coupled to a second phase-shifter in parallel on the silicon substrate characterized in an athermal condition. The dispersion compensator further includes a third phase-shifter on the silicon substrate to the first phase-shifter and the second phase-shifter through two 2×2 splitters to form an optical loop. A second entry port of a first 2×2 splitter is for coupling with an input fiber and a second exit port of a second 2×2 splitter is for coupling with an output fiber. The optical loop is characterized by a total phase delay tunable via each of the first phase-shifter, the second phase-shifter, and the third phase-shifter such that a normal dispersion (>0) at a certain wavelength in the input fiber is substantially compensated and independent of temperature.

Abstract: Mechanisms for customizing a refractive index of an optical component are disclosed. In one example, sub-wavelength openings are formed in a top layer of anti-reflective (AR) material of an optical component to tailor transmission characteristics of the AR material over a range of angles of incidence and a range of wavelengths. In another example, sub-wavelength openings are formed at different filling fractions in the surface of the optical component.

Abstract: Examples of diffractive devices comprise a cholesteric liquid crystal (CLC) layer comprising a plurality of chiral structures, wherein each chiral structure comprises a plurality of liquid crystal molecules that extend in a layer depth direction by at least a helical pitch and are successively rotated in a first rotation direction. Arrangements of the liquid crystal molecules of the chiral structures vary periodically in a lateral direction perpendicular to the layer depth direction to provide a diffraction grating. The diffractive devices can be configured to reflect light having a particular wavelength range and sense of circular polarization. The diffractive devices can be used in waveguides and imaging systems in augmented or virtual reality systems.

Abstract: A system and method for a tunable optical delay line. The tunable optical delay line comprises a coarse delay portion that provides a coarse delay amount, the coarse delay portion including a coarse delay selection element in conjunction with a coarse delay element, the coarse delay selection element incorporated on-chip into a photonic integrated circuit (IC) component, the coarse delay element being disposed off-chip of the photonic IC component and interconnected with the coarse delay selection element; and a fine delay element that provides a fine delay amount, the fine delay element interconnected in series with the coarse delay selection element, the optical delay line being tunable to a target delay amount by agglomerating the coarse and fine delay amounts.

Abstract: A wavelength tunable interference filter includes a movable section having a mirror region that faces a first mirror in a first direction and an electrode so provided in a region outside the mirror region in a plan view viewed in the first direction as to surround the mirror region along the circumferential direction thereof, the electrode configured to displace the movable section in the first direction when voltage is applied to the electrode, and the width of the electrode in the plan view varies in the circumferential direction.

Abstract: An apparatus and method for calculating the frequency of the light.

Abstract: An improved waveguide is disclosed. The waveguide utilizes a luminescent material disposed within or around its perimeter to introduce additional light into the waveguide. For example, the waveguide may include a plurality of planar layers having different refractive indexes. A luminescent material may be disposed along the outer edge of these layers. When light from within the waveguide strikes the luminescent material, it emits light, thereby adding to the light in the waveguide. Not only does the luminescent material introduce more light into the waveguide, it also introduces more light sources, thereby making it more difficult to introduce a probe without blocking at least a portion of the light destined for the image sensor. The luminescent material may be a phosphor.

Abstract: A system, in an active reflector device, adjusts a first amplification gain of each of a plurality of radio frequency (RF) signals received at a receiver front-end from a first equipment via a first radio path of an NLOS radio path. A first phase shift is performed on each of the plurality of RF signals with the adjusted first amplification gain. A combination of the plurality of first phase-shifted RF signals is split at a transmitter front-end. A second phase shift on each of the split first plurality of first phase-shifted RF signals is performed. A second amplification gain of each of the plurality of second phase-shifted RF signals is adjusted.

Abstract: A system, in an active reflector device, adjusts a first amplification gain of each of a plurality of radio frequency (RF) signals received at a receiver front-end from a first equipment via a first radio path of an NLOS radio path. A first phase shift is performed on each of the plurality of RF signals with the adjusted first amplification gain. A combination of the plurality of first phase-shifted RF signals is split at a transmitter front-end. A second phase shift on each of the split first plurality of first phase-shifted RF signals is performed. A second amplification gain of each of the plurality of second phase-shifted RF signals is adjusted.

Abstract: A system, in an active reflector device, adjusts a first amplification gain of each of a plurality of radio frequency (RF) signals received at a receiver front-end from a first equipment via a first radio path of an NLOS radio path. A first phase shift is performed on each of the plurality of RF signals with the adjusted first amplification gain. A combination of the plurality of first phase-shifted RF signals is split at a transmitter front-end. A second phase shift on each of the split first plurality of first phase-shifted RF signals is performed. A second amplification gain of each of the plurality of second phase-shifted RF signals is adjusted.

Abstract: Provided a two-dimensional photonic crystal device in which are inserted three waveguides and one resonant cavity by the creation of linear and local defects. Due to the photonic band gap related to the photonic crystal, electromagnetic signals are confined to the interior of waveguides and resonant cavity. By exciting dipole modes in the resonant cavity, with orientation that depends on the intensity of the applied DC magnetic field, the present circulator device can provide the nonreciprocal transmission of signals in the clockwise and counterclockwise directions. It can fulfill the isolation function and it is fork-shaped, providing greater flexibility in the design of integrated optical communication systems.

Abstract: A system for continuously phase tuning an optical signal includes one optical switch coupled to a phase modulator having a first waveguide with a first phase shifter and a second waveguide with a second phase shifter. The optical switch alternately switches between the first and second phase shifters to phase shift the optical signal, respectively. The continuously phase tuning system further includes a loop mirror that alternately receives the phase shifted optical signal from the first and second waveguides in accordance with the switching, via corresponding first and second mirror inputs, respectively, and reflects the phase shifted optical signal back to the same first or second mirror input at which the phase shifted optical signal was received. First and second phase values of the first and second phase shifters are determined such that overall phase change continues to accumulate substantially linearly.

Abstract: There is provided a method for manufacturing an optical-fibre sensor device, including an enclosure defining a cavity and an optical-fibre sensor including an optical-fibre and a device for holding the sensor rigidly connected to the optical fibre, the optical fibre passing through the holding device between two attachment points. The method comprises: positioning the optical-fibre sensor in the enclosure to pass the fibre through two passage openings provided on the enclosure, which defines two optical-fibre portions in the enclosure, on either side of the holding device, each fibre portion extending between one of the attachment points and one of the passage openings; holding the optical-fibre sensor in position; performing a differential elongation of the enclosure relative to the optical-fibre sensor in the longitudinal direction and towards the outside of the enclosure, the optical-fibre sensor remaining held in position; attaching the optical fibre to the enclosure at the passage openings.

Abstract: Apparatus for generating ultraviolet (UV) pulsed laser-radiation for material-processing includes a laser-source providing infrared (IR) pulsed laser-radiation and a frequency-conversion module. A lithium tetraborate (Li2B4O7) crystal located within the frequency-conversion module converts the IR pulsed laser-radiation to UV pulsed laser-radiation by non-linear harmonic generation. The frequency-conversion module is an airtight enclosure that may be evacuated or contain a dry gas. A flexible optical fiber-assembly transports the IR pulsed laser-radiation from the laser-source to the frequency-conversion module.