A hollow-core antiresonant fiber (HC-ARF) with nested supporting rings (NSRs) has a fiber structure that includes from the inside out a fiber core, a first silica antiresonant ring (SARR), a first air antiresonant ring (AARR), a second SARR, a second AARR and an external silica wall. The fiber structure further includes a first NSR within the first AARR and a second NSR within the second AARR. The HC-ARF with NSRs has advantages and benefits of low confined loss (CL), large bandwidth, simple structure and very good bending characteristics. Therefore, the application fields of HC-ARF are greatly expanded.

A monitorable hollow core (HC) optical fiber comprises one or more hollow core anti-resonant fiber (HC-ARF) segments and one or more monitoring segments alternatingly connected with the HC-ARF segments, and where each monitoring segment comprises one or more non-HC-ARF constituents. A method for monitoring a monitorable HC optical fiber comprises transmitting one or more first optical signals on the monitorable HC optical fiber, detecting one or more second optical signals on the monitorable HC optical fiber, and monitoring one or more optical properties of the monitorable HC optical fiber using the first optical signals and the second optical signals, where the monitoring is enabled as a result of interactions between the first optical signals and the non-HC-ARF constituents of the monitoring segments.

A monitorable hollow core (HC) optical fiber comprises one or more hollow core anti-resonant fiber (HC-ARF) segments and one or more monitoring segments alternatingly connected with the HC-ARF segments, and where each monitoring segment comprises one or more non-HC-ARF constituents. A method for monitoring a monitorable HC optical fiber comprises transmitting one or more first optical signals on the monitorable HC optical fiber, detecting one or more second optical signals on the monitorable HC optical fiber, and monitoring one or more optical properties of the monitorable HC optical fiber using the first optical signals and the second optical signals, where the monitoring is enabled as a result of interactions between the first optical signals and the non-HC-ARF constituents of the monitoring segments.

An optical fiber, an apparatus for receiving input radiation and broadening a frequency range, a radiation source, a metrology arrangement and a lithographic apparatus are provided. The optical fiber comprises a hollow core, a cladding portion and a support portion. The cladding portion surrounds the hollow core and comprises a plurality of anti-resonance elements for guiding radiation through the hollow core. The support portion surrounds and supports the cladding portion and comprises an inner support portion, an outer support portion and a deformable connecting portion that connects the inner support portion to the outer support portion.

A hollow-core antiresonant fiber (HC-ARF) with nested supporting rings (NSRs) has a fiber structure that includes from the inside out a fiber core, a first silica antiresonant ring (SARR), a first air antiresonant ring (AARR), a second SARR, a second AARR and an external silica wall. The fiber structure further includes a first NSR within the first AARR and a second NSR within the second AARR. The HC-ARF with NSRs has advantages and benefits of low confined loss (CL), large bandwidth, simple structure and very good bending characteristics. Therefore, the application fields of HC-ARF are greatly expanded.

An anti-resonant hollow core optical fiber having multiple resonant layers. The optical fiber comprises a low-refractive index core region (1) and a high-refractive index cladding region. The high-refractive index cladding region comprises an inner cladding region (4) and an outer cladding region (5). The outer cladding region (5) clads the inner cladding region (4) and the core region (1). The inner cladding region (4) comprises a first anti-resonant layer (2) and a second anti-resonant layer (3), and the first anti-resonant layer (2) and the second anti-resonant layer (3) surround the core region (1); and the first anti-resonant layer (2) comprises several layers of microcapillary tubes, and the second anti-resonant layer (3) supports the first anti-resonant layer (2). The optical fiber adopts a double-cladding structure and uses two or more anti-resonant layers such that theoretically simulated loss is reduced to 0.1 dB/km, and has the features of ultralow transmission loss, wide spectral bandwidth, low bending loss, low transmission loss, high damage threshold and single-mode transmission.

A photonic-crystal-fiber-delivered laser-triggered high-voltage gas switch can deliver a peak irradiance of greater than 5.110.sup.11 W/cm.sup.2 to the AK gap for a laser having a wavelength of 1064 nm. The switch is capable of operating at pressures up to 2200 psi; voltages across the gap of greater than 200 kV; operation at less than 70% self-break voltage; shot-to-shot jitter of less than 3 ns; AK gap distances of 3 mm or smaller; and triggering via a fiber-delivered laser pulse energy of as low as 500 J.

A hollow-core photonic crystal fiber (HC-PCF)(10) for guiding at least one mode of a light field(1) along a mode guiding section(11) of the HC-PCF(10), comprises an outer jacket(12), an inner cladding(13) and a hollow core(14), which extend along the HC-PCF(10), wherein the inner clad-ding(13) is arranged on an interior surface of the outer jacket(12) and comprises anti-resonant structures(15) surrounding the hollow core(14), and the hollow core(14) has a mode guiding core diameter(d) provided along the mode guiding section of the HC-PCF(10), and wherein at least one fiber end (16) of the HC-PCF(10) has a light field coupling section(17) in which the hollow core(14) is tapered over an axial coupling section length from a fiber end core diameter(D) at the at least one fiber end (16) to the mode guiding core diameter(d). Furthermore, methods of using the HC-PCF and manufacturing the HC-PCF are described.

The present disclosure provides a hollow-core microstructure optical fiber preform, an optical fiber, and a method for manufacturing thereof. An objective of the present disclosure is to introduce a support sheet into a nested structure unit of the hollow-core microstructure optical fiber preform, which not only increases the number of reflection surfaces without increasing the number of nested layers of glass tubes, but also achieves a more accurate positioning by the support sheet and improves manufacturing accuracy as compared to a tangential structure of nested glass tubes, such that the following technical problems, difficulty in controlling a curvature of reflection surfaces, low manufacturing accuracy, large difference between actual loss and theoretical loss, or poor batch consistency, in related anti-resonance optical fibers, caused by increasing the number of layers of nested microstructure units in order to increase the number of reflection surfaces, are solved.

The disclosed embodiments generally relate to extruding multiple layers of micro- to nano-polymer layers in a tubular shape. In particular, the aspects of the disclosed embodiments are directed to a method for producing a Bragg reflector comprising co-extrusion of micro- to nano-polymer layers in a tubular shape.