Optical fiber device, optical system, and optical measurement method

Abstract

The invention relates to an optical fiber device (10) for an optical system (100). The fiber optic device (10) includes a first fluid container (12) having a fluid inlet (12a), a fluid outlet (12b) and a light transmissive window (12c). The fiber optic device (10) also includes a second fluid container (14) having a fluid inlet (14a), a fluid outlet (14b) and a light transmissive window (14c). The fiber optic device (10) further comprises a hollow-core fiber (16) fluidly connecting the fluid outlet (12b) of the first fluid container (12) with the fluid inlet (14a) of the second fluid container (14) and arranged for directing light incident on the light-transmissive window (12c) of the first fluid container (12) to the light-transmissive window (14c) of the second fluid container (14), where the hollow-core fiber (16) is preferably a twisted single-ring hollow-core fiber. The invention also relates to an optical system (100) comprising such an optical fiber device (10) and to a method for performing optical measurements using such an optical system (100).

Description

Technical Field

[0001] This invention relates to an optical fiber device for use in an optical system. It also relates to an optical system incorporating such an optical fiber device, and an optical measurement method preferably using this optical system. The invention can be applied to the field of chiral optical sensing, for example, measuring the optical rotation, circular dichroism, and / or helical dichroism of fluid samples to, for example, detect the purity of samples containing enantiomeric molecules. In particular, the invention can be used in the pharmaceutical industry to analyze the optical rotation, circular dichroism, and / or helical dichroism of small-volume fluid samples. Background Technology

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[16] Ni, J.; Liu, S.; Hu, G.; Hu, Y.; Lao, Z.; Li, J.; Zhang, Q.; Wu, D.; Dong, S.; Chu, J.; Qiu, C.-W., “Giant Helical Dichroism of Single Chiral Nanostructures with Photonic Orbital Angular Momentum”, ACS Nano, 2021, Vol. 15, No. 2, pp. 2893-2900, https: / / doi.org / 10.1021 / acsnano.0c08941

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[19] Davtyan, S.; Chen, Y.; Frosz, MH; Russell, PSJ; Novoa, D., “Robust Excitation and Raman Conversion of Guided Vortices in a Chiral Gas-Filled Photonic Crystal Fiber”, Optics Letters, 2020, Vol. 45, No. 7, pp. 1766-1769, https: / / doi.org / 10.1364 / OL.383760

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[21] Uebel, P.; Günendi, MC; Frosz, MH; Ahmed, G.; Edavalath, NN; Ménard, J.-M.; Russell, PSJ, “Broadband Robustly Single-Mode Hollow-Core PCF by Resonant Filtering of Higher-Order Mode”, Optics Letters, 2016, Vol. 41, No. 9, pp. 1961-1964, https: / / doi.org / 10.1364 / OL.41.001961

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[35] EP3649090B1

[36] EP3136143A1

[37] EP4030230A1

[38] EP4163715 A1

[39] F. Schorn et al., “Measurement of Minute Liquid Volumes of Chiral Molecules Using In-Fiber Polarimetry”, Analytical Chemistry, 2023, Vol. 95, No. 6, pp. 3204-3209.

[40] F. Schorn et al., “Analysis of the chemical composition of chiral components by in-fiber polarimetry,” 55th Annual Meeting of the German Catalytic Chemists, No. B.11.14

[0003] Chiral optical effects provide a convenient way to optically distinguish the two enantiomers of chiral media and control the polarization of light. The well-established circular dichroism (CD) technique has long been used to characterize chemical and biological samples and to realize optical elements that select the helicity of circularly polarized light (also known as spin angular momentum (SAM)) [1]. In recent years, advances in understanding and fabrication techniques of nanostructures, metamaterials and optical fibers have led to new optical devices with customized, broadband and enhanced chiral optical properties, as well as platforms for enhancing enantioselectivity [2-8].

[0004] In contrast, helical dichroism (HD), similar to CD based on orbital angular momentum (OAM), has been less studied and has only begun to attract attention in the last two decades. Nevertheless, this effect has been observed in a variety of systems, both natural (e.g., molecules [9, 10]) and artificial

[11] , and some studies have reported its application in distinguishing point-like (relative to light wavelength) enantiomers with opposite chirality [12, 13]. Defining OAM dichroism is more complex than CD because different combinations of SAM and topological charge (i.e., OAM value) can lead to different responses

[14] . In recent years, an increasing number of research teams have reported nanostructures and metasurfaces exhibiting HD properties, and these nanostructures and metasurfaces have achieved high extinction ratios by designing their feature dimensions to be comparable to (or even greater than) the light wavelength [15-17]. On the other hand, helical dichroic waveguides have not yet been reported. Although it is possible to design them to have strong CD and excellent waveguide performance for carrying OAM modes, and to provide a promising alternative platform for modulating the properties of light and enhancing the interaction of chiral light with matter [18-20].

[0005] To measure chiral optical effects in fluid samples, known measuring devices typically use cuvettes to hold the sample and perform measurements during polarized light irradiation. For this purpose, cuvettes are made of transparent materials such as plastic, glass, or fused silica so that light can pass through both the cuvette and the sample.

[0006] The drawback of these traditional apparatuses is that cuvettes typically have a relatively large volume in order to ensure sufficient interaction distance between the light and the sample. This is especially true in the field of pharmacology, where only a small amount of the analyte (e.g., a drug) is usually available. Summary of the Invention

[0007] Therefore, the object of the present invention is to provide an improved method for measuring the chiral optical effects of fluid samples, wherein the disadvantages and limitations of conventional techniques are preferably avoided. In particular, the object of the present invention is to provide a solution for measuring the chiral optical effects of fluid samples that can analyze small-volume samples and / or provide a longer light-sample interaction length.

[0008] These objectives are achieved by fiber optic devices, optical systems, and methods, each incorporating the features of the independent claims. Preferred embodiments and applications of the invention are given in the dependent claims.

[0009] According to a first general aspect of the invention, an optical fiber device is provided for optical systems (e.g., for chiral optical sensing, such as measuring the optical rotation, circular dichroism, and / or helical dichroism of a fluid sample).

[0010] The fiber optic device includes a fluid container (e.g., a fluid pool), which, for ease of distinction, will be referred to hereinafter as a "first" fluid container. The first fluid container has (e.g., a first) fluid inlet (e.g., an inlet port and / or inlet opening), (e.g., a first) fluid outlet (e.g., an outlet port and / or outlet opening), and (e.g., a first) light-transmitting (e.g., glass) window. The first fluid container may be defined by (e.g., a rigid) first container body and / or enclose (e.g., a fixed volume) a first fluid reservoir, which is preferably used to receive and / or contain fluid samples.

[0011] The fiber optic device also includes a "second" fluid container (e.g., a second fluid pool). The second fluid container has (e.g., a second) fluid inlet (e.g., an inlet port and / or inlet opening), (e.g., a second) fluid outlet (e.g., an outlet port and / or outlet opening), and (e.g., a second) light-transmitting (e.g., glass) window. The second fluid container may be defined by (e.g., a rigid) second container body and / or enclose (e.g., a fixed-volume) second fluid reservoir, which is preferably used to receive and / or contain fluid samples.

[0012] The optical fiber device also includes a hollow optical fiber. For example, the hollow optical fiber may be an optical fiber having a hollow region (e.g., a center) for guiding light, such that preferably only a small fraction of the optical power propagates within the solid optical fiber material. The hollow optical fiber fluidly connects the fluid outlet of a first fluid container to the fluid inlet of a second fluid container, and is preferably used for transmitting and / or exchanging fluid samples between the first and second fluid containers (e.g., between first and second fluid storage devices). Furthermore, the hollow optical fiber is arranged to guide light incident on a (e.g., a first) light-transmitting window of the first fluid container to a (e.g., a second) light-transmitting window of the second fluid container. For this purpose, the hollow optical fiber may be arranged such that light incident on the (e.g., a first) light-transmitting window of the first fluid container is coupled into the hollow optical fiber, propagates through the hollow optical fiber, and exits from the hollow optical fiber toward the (e.g., a second) light-transmitting window of the second fluid container.

[0013] Specifically, the hollow-core fiber is a single-ring hollow-core fiber. For example, the hollow-core fiber may consist only of a single-ring hollow tube (e.g., each hollow tube has a circular or elliptical cross-section) surrounding a hollow region (e.g., filled with air or a fluid sample), as will be described in more detail below. Therefore, the hollow-core fiber is preferably not based on a photonic crystal structure or Kagome fiber. In a preferred embodiment, the hollow-core fiber is a (e.g., helically twisted) single-ring hollow-core fiber. For example, the hollow-core fiber may be helically twisted around its (e.g., central) longitudinal axis or fiber axis (e.g., internally), preferably such that the hollow tube does not extend in a straight line but is helically wound around the hollow region along the longitudinal / fiber axis.

[0014] Advantageously, by providing the ability to measure fluid samples within a hollow-core fiber, the fiber optic device claimed in this invention requires a significantly reduced sample volume (at least 1000 times less) compared to currently commercially available systems. Furthermore, this fiber optic device provides a longer light-sample interaction length (essentially determined by the length of the hollow-core fiber), thereby improving the sensitivity required for chiral measurements. In this regard, the special design of the fiber ensures that the properties of the light passing through the fiber are not significantly altered, thus not affecting chiral measurements. For example, using the single-ring hollow-core fiber claimed in this invention allows for the suppression of unwanted higher-order modes, which is necessary to ensure excellent polarization-preserving performance, and provides low wavelength-independent birefringence.

[0015] According to a first aspect of this disclosure, a first fluid container and a second fluid container may be arranged at opposite and / or different ends (e.g., opposite and / or different distal ends) of a hollow optical fiber. For example, the first fluid container may be arranged at a first end (e.g., a first distal end) of the hollow optical fiber, while the second fluid container may be arranged at a (e.g., a different) second end (e.g., a second distal end) of the hollow optical fiber, which is arranged opposite to the first end. In this case, the first end of the hollow optical fiber may (e.g., at least partially) be accommodated in and / or connected to the (e.g., a first) outlet of the first fluid container, while the second end of the hollow optical fiber may (e.g., at least partially) be accommodated in and / or connected to the (e.g., a second) inlet of the second fluid container.

[0016] Alternatively or supplementally, hollow-core optical fibers may include multiple (e.g., independent) fluid pathways (e.g., fluid channels), each fluid pathway configured to transport a fluid sample between a first fluid container (e.g., its first fluid reservoir) and a second fluid container (e.g., its second fluid reservoir). For example, the hollow region of the hollow-core optical fiber may be one of multiple fluid pathways. Alternatively or supplementally, the interior of each tube in a single-ring hollow tube may be another of multiple fluid pathways.

[0017] Alternatively or supplementally, the length of the hollow fiber can be between 1 cm and 2 m, preferably between 5 cm and 50 cm, and particularly preferably between 10 cm and 30 cm. Advantageously, this allows for a beneficial balance between the interaction length and the desired sample volume.

[0018] According to another aspect of this disclosure, the hollow optical fiber may include an outer cladding region (e.g., with a ring-shaped cross-section). The hollow optical fiber may also include (e.g., five) hollow tubes surrounded by the outer cladding region, wherein, preferably, each hollow tube is fused to the outer cladding region, for example, to form (e.g., concentric) rings around a hollow region (or the hollow region) of the hollow optical fiber (e.g., in cross-section).

[0019] According to another aspect of the present disclosure, the hollow-core optical fiber may include (e.g., exactly) five hollow tubes. For example, the hollow-core optical fiber may be a single-ring five-tube hollow-core optical fiber. This design has proven to have particularly advantageous light guiding characteristics.

[0020] Additionally or alternatively, each hollow tube (e.g., in a plane perpendicular to the longitudinal axis of the hollow-core optical fiber) may have a circular cross-section. Alternatively, each hollow tube may have an elliptical cross-section.

[0021] Additionally or alternatively, the hollow tubes may not be in contact with each other (e.g., not directly in contact with each other). For example, there may be free space between every two adjacent hollow tubes, and / or the hollow tubes may be connected only through the outer cladding region.

[0022] Additionally or alternatively, the hollow tubes may be symmetrically arranged around the hollow core region. For example, in a plane perpendicular to the longitudinal axis of the hollow-core optical fiber, the hollow tubes may form a regular polygon (e.g., a pentagon), and / or may be arranged as a regular polygon (e.g., a pentagon).

[0023] Additionally or alternatively, each hollow tube may not include nested sub-tubes. For example, each hollow tube may be hollow, and preferably no sub-structures are arranged inside the corresponding hollow tube.

[0024] According to another aspect of the present disclosure, the hollow core region (e.g., in a plane perpendicular to the longitudinal axis of the hollow-core optical fiber) may have a core diameter D, which is greater than 10 μm, preferably greater than 14 μm. Additionally or alternatively, the core diameter D of the hollow core region may be less than or equal to 22 μm, preferably less than or equal to 20 μm. For example, the value range of D may be 10 μm < D ≤ 22 μm, preferably 14 μm < D ≤ 20 μm.

[0025] Additionally or alternatively, each hollow tube (e.g., in a plane perpendicular to the longitudinal axis of the hollow-core optical fiber) may have an inner tube diameter d, where the ratio of the inner tube diameter to the core diameter (i.e., d / D) may be between 0.66 and 0.73 (e.g., 0.7), and / or where the inner tube diameter may be less than the core diameter, i.e., d < D.

[0026] Additionally or alternatively, the high-order mode (HOM) suppression ability of the hollow-core optical fiber may be at least 40 dB / m, preferably at least 70 dB / m, particularly preferably at least 110 dB / m. Advantageously, by suppressing the HOM, the polarization purity of the light propagating along the hollow-core optical fiber can be ensured.

[0027] Alternatively or supplementarily, the hollow fiber can be a twisted hollow fiber, wherein the twist rate (e.g., along its longitudinal axis or fiber axis) (e.g., internally) is between 10 rad / m and 300 rad / m, preferably between 30 rad / m and 200 rad / m, and particularly preferably between 50 rad / m and 150 rad / m. In this case, the twist rate preferably refers to the twist of the internal structure, i.e., the twist of the hollow tube around the hollow region. Advantageously, by using the aforementioned twist rate, linear birefringence and its wavelength dependence can be reduced, while ensuring high loss for HOM.

[0028] Alternatively or supplementarily, the wall thickness of each hollow tube can be between 100 nm and 1 µm, preferably between 200 nm and 800 nm, and particularly preferably between 300 nm and 750 nm. For example, the wall thickness can be the distance between the inner and outer radii of the corresponding hollow tube in a plane perpendicular to the longitudinal axis of the hollow fiber. In a preferred embodiment, the wall thickness of each hollow tube can be 350 nm or 700 nm.

[0029] According to another aspect of this disclosure, the outer sheath region can directly contact each hollow tube. For example, the hollow tube can be fixed (e.g., welded) to the outer sheath region.

[0030] Alternatively or supplementally, each hollow tube may be (e.g., directly) attached to the outer sheath area.

[0031] Alternatively or supplementally, the thickness T of the cladding region may be at least 20 μm, preferably at least 70 μm, and particularly preferably at least 150 μm. Advantageously, these cladding thicknesses ensure that the hollow fiber can withstand mechanical stress and provide a sufficient polarization extinction ratio.

[0032] Alternatively or supplementally, the outer cladding area and / or hollow tube may be made of fused silica glass and / or soft glass.

[0033] According to another aspect of this disclosure, the (e.g., first) light-transmitting window of the first fluid container and the (e.g., first) fluid outlet of the first fluid container can be arranged to be (e.g., directly) opposite each other and / or flush with each other. For example, there can be a direct (e.g., straight) line of sight between the (e.g., first) light-transmitting window of the first fluid container and the (e.g., first) fluid outlet of the first fluid container. Additionally or alternatively, the (e.g., first) light-transmitting window of the first fluid container and the first end (e.g., the first distal end) of the hollow optical fiber can also be arranged to be (e.g., directly) opposite each other and / or flush with each other. Advantageously, this ensures efficient coupling of light into the hollow optical fiber.

[0034] Alternatively or supplementarily, the (e.g., second) light-transmitting window of the second fluid container and the (e.g., second) fluid inlet of the second fluid container can be arranged to be (e.g., directly) opposite each other and / or flush with each other. For example, there can be a direct (e.g., straight) line of sight between the (e.g., second) light-transmitting window of the second fluid container and the (e.g., second) fluid inlet of the second fluid container. Alternatively or supplementarily, the (e.g., second) light-transmitting window of the second fluid container and the second end (e.g., the second distal end) of the hollow fiber can also be arranged to be (e.g., directly) opposite each other and / or flush with each other. Advantageously, this ensures efficient light extraction from the hollow fiber.

[0035] Alternatively or supplementarily, the (e.g., first) fluid inlet and (e.g., first) fluid outlet of the first fluid container may be arranged at an angle (e.g., perpendicular) to each other, preferably such that the fluid sample undergoes a change of direction along the path from the (e.g., first) fluid inlet to the (e.g., first) fluid outlet of the first fluid container. For example, the (e.g., first) fluid inlet and (e.g., first) fluid outlet may not be arranged parallel and / or located on the same side or opposite sides of the first fluid container.

[0036] Alternatively or supplementarily, the (e.g., second) fluid inlet and (e.g., second) fluid outlet of the second fluid container may be arranged at an angle (e.g., vertical) to each other, preferably such that the fluid sample undergoes a change of direction along the path from the (e.g., second) fluid inlet to the (e.g., second) fluid outlet of the second fluid container. For example, the (e.g., second) fluid inlet and (e.g., second) fluid outlet may not be arranged parallel and / or located on the same side or opposite sides of the second fluid container.

[0037] Alternatively or supplementally, the hollow fiber (e.g., its profile and / or outer boundary) may extend in a straight line between the first and second fluid containers. This does not affect the possibility of employing a torsional geometry within the hollow fiber, wherein the hollow tube is spirally wound around the hollow region along the longitudinal axis / fiber axis.

[0038] According to another aspect of this disclosure, the optical fiber device may include a first coupling element (e.g., a collar). Thus, the first end (e.g., a first terminal) of the hollow optical fiber can preferably be housed in the first coupling element. Alternatively or supplementarily, the hollow optical fiber (e.g., its first end) is preferably secured to a first fluid container (e.g., its outlet) by the first coupling element (e.g., preferably by force locking and / or shape locking) (e.g., pressure sealing). For example, the first coupling element can interconnect the hollow optical fiber (e.g., its first end) with the first fluid container (e.g., its outlet) (e.g., mechanically).

[0039] In a preferred embodiment, the first coupling element and the first fluid container (e.g., its outlet) can be interconnected via (e.g., a first) threaded connection (e.g., pressure-sealed). For example, the first coupling element and the first fluid container (e.g., its outlet) may each have mating threads.

[0040] Alternatively or supplementally, the optical fiber device may include at least one first sealing element disposed between the first coupling element and the hollow optical fiber (e.g., between the first coupling element and a first end of the hollow optical fiber). Preferably, the at least one first sealing element is tubular (e.g., a sealing tube) and / or circumferentially surrounds the hollow optical fiber (e.g., its first end). Alternatively or supplementally, the at least one first sealing element may be (e.g., elastically) deformable, preferably for protecting the hollow optical fiber from excessive pressure loads. The first coupling element and the hollow optical fiber may be fluidly sealed to each other by the at least one first sealing element.

[0041] According to another aspect of this disclosure, the optical fiber device may include a second coupling element (e.g., a collar). Thus, the second end (e.g., a second terminal) of the hollow optical fiber can preferably be accommodated in the second coupling element. Alternatively or supplementarily, the hollow optical fiber (e.g., its second end) is preferably secured to a second fluid container (e.g., its inlet) by the second coupling element (e.g., preferably by force locking and / or shape locking, e.g., pressure sealing). For example, the second coupling element can interconnect the hollow optical fiber (e.g., its second end) with the second fluid container (e.g., its inlet) (e.g., mechanically).

[0042] In a preferred embodiment, the second coupling element and the second fluid container (e.g., its inlet) can be interconnected via (e.g., a second) threaded connection (e.g., pressure-sealed). For example, the first coupling element and the second fluid container (e.g., its inlet) may each have mating threads.

[0043] Alternatively or supplementally, the optical fiber device may include at least one second sealing element disposed between the second coupling element and the hollow optical fiber (e.g., between the second coupling element and a second end of the hollow optical fiber). Preferably, the at least one second sealing element is tubular (e.g., a sealing tube) and / or circumferentially surrounds the hollow optical fiber (e.g., its first end). Alternatively or supplementally, the at least one second sealing element may be (e.g., elastically) deformable, preferably for protecting the hollow optical fiber from excessive pressure loads. The second coupling element and the hollow optical fiber can be fluidly sealed to each other by at least one second sealing element.

[0044] According to another aspect of this disclosure, the hollow-core optical fiber can be detachably connected to a first fluid container (e.g., its first outlet). For example, the hollow-core optical fiber can be reversibly attached to and detached from the first fluid container, for example, via a clamp and / or threaded connection (e.g., a first). Alternatively or supplementarily, the hollow-core optical fiber can be detachably connected to a second fluid container (e.g., its second inlet). For example, the hollow-core optical fiber can be reversibly attached to and detached from the second fluid container, for example, via a clamp and / or threaded connection (e.g., a second).

[0045] Alternatively or concurrently, the hollow optical fiber, the first fluid container, and the second fluid container may be integrally connected to each other, for example, forming a single unit. Preferably, the hollow optical fiber, the first fluid container, and the second fluid container cannot be separated from each other in a non-destructive manner. For example, the hollow optical fiber, the first fluid container, and the second fluid container may be fused and / or welded together, and / or formed as a single unit.

[0046] According to another general aspect of this disclosure, an optical system (e.g., an optical polarimeter system) is provided. Preferably, this optical system is for optical measurement, particularly preferably for measuring the optical rotation (e.g., optical rotation degree) and / or circular dichroism and / or spiral dichroism (e.g., enantiomeric excess of the fluid sample) of a fluid sample. This optical system includes the fiber optic device disclosed herein. Therefore, the limiting features related to the fiber optic device disclosed herein should also be disclosed and claimed in the section related to the optical system. Conversely, the reverse is also true.

[0047] The optical system also includes a polarization source device (e.g., a polarized laser source device) configured and arranged to generate a polarized light beam (e.g., a circularly polarized beam or a linearly polarized beam) incident on a (e.g., a first) light-transmitting window of a first fluid container (e.g., having a known and / or well-defined polarization state). For example, the polarization source device may include a light source configured to directly emit a beam having a well-defined polarization state (e.g., circularly or linearly polarized). Alternatively, the polarization source device may include a light source configured to emit unpolarized light and a polarizer configured to polarize the emitted light to generate a polarized beam. To measure helical dichroism, the polarization source device may also optionally be configured to generate a polarized beam carrying a topological charge. For example, the polarization source device may be configured to excite a topological charge via a vortex retarder.

[0048] The optical system also includes a polarization detection device (e.g., a polarization analyzer). The polarization detection device may be arranged to receive an output beam emitted from a (e.g., a second) light-transmitting window of a second fluid container and / or configured to generate an output signal that depends on (e.g., varies with) the polarization state of the received output beam. For example, the polarization detection device may be configured to determine and / or measure the (e.g., spatial) polarization state of the received output beam. In this case, the polarization detection device may, for example, include (e.g., a movable) analyzer polarizer (e.g., a Nicol prism, a Wollaston prism, and / or a wire grid polarizer) and / or a photodetector.

[0049] Advantageously, the optical system is capable of reliably measuring the optical properties of fluid samples, particularly optical rotation and / or helical dichroism and / or circular dichroism (e.g., enantiomeric excess), where only a small amount of fluid sample is required compared to currently commercially available systems.

[0050] According to one aspect of this disclosure, the polarized beam can be linearly polarized. Alternatively, the polarized beam can be circularly polarized.

[0051] Alternatively or supplementally, the wavelength of the polarized beam may be between 100 nm and 2000 nm, preferably between 200 nm and 1000 nm, and particularly preferably between 400 nm and 600 nm. For example, the polarized beam may include UV light, IR light, and / or visible light.

[0052] Alternatively or supplementally, the polarizing light source device may be directly attached to the (e.g., first) light-transmitting window of the first fluid container. For example, the polarizing light source device may be bonded and / or fused to the (e.g., first) light-transmitting window of the first fluid container. Alternatively or supplementally, the polarizing light source device may be directly adjacent to the (e.g., first) light-transmitting window of the first fluid container. For example, there may be no (air) gap between the polarizing light source device and the (e.g., first) light-transmitting window of the first fluid container. Alternatively or supplementally, the polarizing light source device may be supported by the (e.g., first) light-transmitting window of the first fluid container. For example, the polarizing light source device may be configured as a lightweight light-emitting diode (LED) device directly connected to the (e.g., first) light-transmitting window of the first fluid container.

[0053] Additionally or alternatively, a polarization source device may include a light source (e.g., a laser source) configured to generate (and / or emit) a light beam. This beam may be polarized or unpolarized. The polarization source device may also include a polarizer (e.g., a linear polarizer) arranged to polarize the generated beam (e.g., to a well-defined polarization state) to produce a polarized beam. For example, the polarizer may be (e.g., an absorption-type and / or beam-splitting type) linear analyzer, and / or include waveplates (e.g., half-wave plates and / or quarter-wave plates).

[0054] According to another aspect of this disclosure, the polarization detection device may include an analyzer, preferably rotatable and / or in a rotating state. For example, the analyzer may be a linear analyzer (e.g., an absorption type and / or a beam-splitting type) and / or include a polarizing prism. The analyzer may be arranged to polarize the output beam to produce a polarized detection beam. For example, the analyzer may allow only light waves of the output beam with a specific polarization state to pass through, while blocking light waves of the output beam with other polarization states. Preferably, the analyzer may have a defined orientation (e.g., perpendicular or parallel) relative to the polarizer of the polarization light source device.

[0055] Alternatively or supplementally, the polarization detection device may include a photodetector configured to receive a detection beam and / or configured to generate an output signal based on the intensity, power, energy, and / or wavelength of the received detection beam. For example, the photodetector may include a charge-coupled device (CCD), a complementary metal-oxide-semiconductor (CMOS) device, a phototransistor, and / or a photodiode.

[0056] According to another aspect of this disclosure, the optical system may further include at least one focusing element. For example, at least one focusing element may include a focusing lens, a focusing mirror, and / or a focusing metamaterial structure. Preferably, at least one focusing element is arranged to focus the generated polarized beam onto a (e.g., first) light-transmitting window of a first fluid container and / or a first end (e.g., a first distal end) of a hollow optical fiber. For example, at least one focusing element may be arranged in the beam path between the polarization source device and the (e.g., first) light-transmitting window of the first fluid container. Supplementally or alternatively, at least one focusing element may be arranged to focus an output beam emitted from a (e.g., second) light-transmitting window of a second fluid container onto a polarization detection device. For example, at least one focusing element may be arranged in the beam path between the (e.g., second) light-transmitting window of the second fluid container and the polarization detection device and / or between the analyzer and the polarization detection device.

[0057] Additionally or alternatively, the optical system may also include at least one collimating element. For example, at least one collimating element may include a collimating lens, a collimating mirror, and / or a collimating metamaterial structure. Preferably, at least one collimating element may be arranged to collimate the output beam before it enters the polarization detection device and / or before it reaches the analyzer. For example, at least one collimating element may be arranged in the beam path between the (e.g., second) light-transmitting window of the second fluid container and the polarization detector (e.g., its analyzer).

[0058] In a preferred embodiment, at least one collimating element may include a polarizer collimating element disposed in the beam path between the (e.g., second) light-transmitting window of the second fluid container and the analyzer, and configured and / or arranged to collimate the output beam before it reaches the analyzer. Furthermore, at least one focusing element may include a polarizer focusing element disposed in the beam path between the analyzer and the photodetector, and configured and / or arranged to focus the polarization detection beam generated by the analyzer onto the photodetector. In this case, the polarizer collimating element and / or the analyzer and / or the polarizer focusing element may be integrated into a single component.

[0059] According to another aspect of this disclosure, an optical measurement method is provided. Preferably, the method is used to measure the optical rotation (e.g., optical rotation degree) and / or circular dichroism and / or helical dichroism of a fluid sample (to, for example, determine enantiomer excess). Supplementally or alternatively, the method may also be a method for measuring the Faraday rotation of a fluid sample. Particularly preferably, the method uses an optical system as disclosed herein. Therefore, the limiting features associated with the disclosed optical system and fiber optic device should also be disclosed and claimed in the section related to the method. Conversely, the opposite is also true.

[0060] The method includes introducing (e.g., pressing and / or pumping) a fluid sample into a hollow optical fiber (e.g., its fluid passage), wherein the hollow optical fiber is (e.g., a twisted) single-ring hollow optical fiber. Preferably, this is accomplished using an optical fiber device. For example, the introduction step may include (e.g., using a syringe) applying overpressure at a (e.g., first) fluid inlet of a first fluid container to pressurize the fluid sample from the first fluid container through the hollow optical fiber into a second fluid container. Alternatively or supplementarily, the introduction step may include (e.g., using a pump) applying negative pressure at a (e.g., second) fluid outlet of the second fluid container to draw the fluid sample from the first fluid container into the second fluid container through the hollow optical fiber. Preferably, the introduction step thus includes allowing the fluid sample to flow within the hollow optical fiber from a first end (e.g., a first distal end) to a second end (e.g., a second distal end) of the hollow optical fiber.

[0061] The method also includes passing a polarized beam (e.g., generated by a polarizing light source device) through a hollow fiber and introducing a fluid sample into the hollow fiber. For example, the transmission step may include coupling the polarized beam to a first end (e.g., a first distal end) of the hollow fiber and / or guiding the polarized beam from the first end (e.g., the first distal end) to a second end (e.g., a second distal end) within the hollow fiber. Preferably, the polarized beam thus propagates along the longitudinal axis or fiber axis of the hollow fiber and / or is confined by the cladding region. To couple the polarized beam into the hollow fiber, the transmission step may include guiding the polarized beam to a (e.g., a first) light-transmitting window of a first fluid container and / or the first end (e.g., the first distal end) of the hollow fiber.

[0062] To measure helical dichroism, a polarized beam can optionally carry a topological charge.

[0063] Alternatively, for example, in order to measure Faraday rotation, the method may further include applying a magnetic field to a fluid sample introduced into a hollow fiber to preferably magnetize the fluid sample introduced into the hollow fiber.

[0064] The method further includes: altering the polarization properties (e.g., rotating the polarization direction) of the polarized beam by interacting with the (e.g., magnetized) fluid sample as the polarized beam passes through a hollow optical fiber and a (e.g., magnetized) fluid sample to generate an output beam. For example, the fluid sample may have an optically active and / or chiral medium configured to rotate the polarization direction of the polarized beam. Additionally or alternatively, the fluid sample may contain magnetically active or Faraday-active materials.

[0065] The method further includes measuring and / or determining the polarization state of the generated output beam, preferably by means of a polarization detection device. Additionally or alternatively, the method may also include generating an output signal that depends on (e.g., varies with) the polarization state of the generated output beam, a step preferably performed by a polarization detection device (or the polarization detection device itself). For example, the polarization state can be measured by comparing the polarization characteristics of the polarized beam and the output beam. For example, the step of measuring the polarization state may include measuring the angle by which the polarization state of the output beam is rotated relative to the polarization state of the polarized beam. Additionally or alternatively, the step of measuring the polarization state may include determining the enantiomeric excess of the fluid sample, i.e., the ratio of R-enantiomers to S-enantiomers in the fluid sample, as expressed by the formula (c...). R -c S ) / (c R +c S ), where c R c is the concentration of the R-enantiomer. S The concentration of the S-enantiomer.

[0066] According to one aspect of the invention, the fluid sample may be a liquid (e.g., a liquid solution). Alternatively, the fluid sample may also be gaseous or a gaseous state.

[0067] Alternatively or supplementally, a fluid sample may contain at least one chiral molecule and / or at least one chiral ion. A molecule or ion may be called a chiral molecule or ion if it cannot be superimposed on its mirror image by any combination of rotation, translation, and certain conformational changes.

[0068] Alternatively or supplementally, the fluid sample may contain at least one enantiomer. The enantiomer may be one of two stereoisomers that cannot be superimposed on their own mirror image.

[0069] Alternatively or supplementally, the fluid sample may contain magnetically active or Faraday active materials. A material is called a magnetically active or Faraday active material if it can change the polarization properties of light when placed in a magnetic field.

[0070] According to another aspect of this disclosure, the introduction step includes sequentially pressurizing or aspirating a fluid sample through the following components: an inlet (e.g., a first) of a first fluid container, a hollow optical fiber fluidly connected to an outlet (e.g., a first) of the first fluid container, an inlet (e.g., a second) of a second fluid container fluidly connected to the hollow optical fiber, and an outlet (e.g., a second) of the second fluid container. Preferably, the aforementioned components constitute part of the optical fiber device and / or optical system disclosed herein.

[0071] According to another aspect of this disclosure, when a polarized light beam passes through a hollow fiber and a fluid sample is introduced into the hollow fiber, the fluid sample can flow through the hollow fiber (e.g., continuously). For example, when a polarized light beam passes through a hollow fiber and a fluid sample is introduced into the hollow fiber, there may be (e.g., continuous) fluid sample flow inside the hollow fiber (e.g., this flow is generated by pumping and / or pressurizing the fluid sample through the hollow fiber).

[0072] Alternatively, when a polarized beam passes through a hollow fiber and a fluid sample is introduced into the hollow fiber, the fluid sample may be static and / or may not flow through the hollow fiber. Attached Figure Description

[0073] Further details and advantages of the invention will now be described with reference to the accompanying drawings, which illustrate:

[0074] Figure 1 This is a schematic diagram of an optical fiber device according to one embodiment;

[0075] Figure 2 This is a cross-sectional view of a single-ring hollow fiber according to one embodiment;

[0076] Figure 3 This is a pseudo-3D view of a single-ring hollow fiber according to an embodiment;

[0077] Figure 4 This is a schematic diagram of an optical system according to one embodiment;

[0078] Figure 5 This is a flowchart of an optical measurement method according to one embodiment;

[0079] Figure 6 This is a schematic diagram of an apparatus for characterizing a single-ring hollow-core optical fiber according to an embodiment; and

[0080] Figure 7 This is a schematic diagram of an optical system according to another embodiment. Detailed Implementation

[0081] Figure 1 A schematic diagram (cross-sectional view) of an optical fiber device 10 according to an embodiment is shown. The optical fiber device 10 can be a standalone device, or, for example, as... Figure 4 As shown, this constitutes part of the optical system 100. The fiber optic device 10 and / or the optical system 100 can be used to measure the optical rotation and / or circular dichroism of a fluid sample, wherein the interaction between a polarized beam and the fluid sample is analyzed. In this case, as described below, the fiber optic device 10 advantageously provides a longer length of interaction between the fluid sample and the polarized beam, while requiring only a small amount of fluid sample.

[0082] Figure 1 The illustrated optical fiber device 10 includes a first fluid container 12, a second fluid container 14, and a hollow optical fiber 16 that fluidly connects the first fluid container 12 and the second fluid container 14. Preferably, the hollow optical fiber 16 directly fluidly connects the first fluid container 12 and the second fluid container 14, and / or (e.g., directly) attaches (e.g., fixes) it to the first fluid container 12 and the second fluid container 14.

[0083] The first fluid container 12, the second fluid container 14, and the hollow optical fiber 16 can be configured to contain fluid samples such as liquids or gases. For example, the first fluid container 12 may include (e.g., a fluid-sealed and / or closed) first container body, and / or is defined by the first container body, which, for example, has a plurality of first walls. Similarly, the second fluid container 14 may include (e.g., a fluid-sealed and / or closed) second container body, and / or is defined by the second container body, which, for example, has a plurality of second walls.

[0084] The optical fiber device 10 may be configured to allow a fluid sample to flow from a first fluid container 12 to a second fluid container 14 via a hollow optical fiber 16, or vice versa. For example, a fluid sample may be exchanged between the first fluid container 12 and the second fluid container 14 via the hollow optical fiber 16. In this case, the first fluid container 12 and the second fluid container 14 may be arranged at opposite ends of the hollow optical fiber 16, and / or the hollow optical fiber 16 may provide at least one fluid path configured for transferring a fluid sample between the first fluid container 12 and the second fluid container 14.

[0085] Preferably, the fluid sample contains an optically active material. For example, the fluid sample may contain at least one chiral molecule and / or at least one chiral ion. The fluid sample may be an organic sample or an inorganic sample.

[0086] To introduce a fluid sample into the first fluid container 12, the first fluid container 12 and / or its first container body may include a fluid inlet 12a, which may be referred to as the "first" fluid inlet 12a for easy distinction. For example, the first fluid inlet 12a may be configured as an inlet port and / or an inlet opening. Furthermore, the first fluid container 12 and / or its first container body may include a fluid outlet 12b, which may be referred to as the "first" fluid outlet 12b for easy distinction. For example, the first fluid outlet 12b may be configured as an outlet port and / or an outlet opening. Preferably, the first fluid inlet 12a and the first fluid outlet 12b are arranged on different sides and / or first walls of the first container body. For example, the first fluid inlet 12a and the first fluid outlet 12b may be arranged obliquely (e.g., vertically) to each other.

[0087] Similarly, the second fluid container 14 and / or its second container body may include a fluid inlet 14a, which may be referred to as the "second" fluid inlet 14a for easy distinction. For example, the second fluid inlet 14a may be configured as an inlet port and / or an inlet opening. Furthermore, the second fluid container 14 and / or its second container body may include a fluid outlet 14b, which may be referred to as the "second" fluid outlet 14b for easy distinction. The second fluid outlet 14b may be configured as, for example, an outlet port and / or an outlet opening. Preferably, the second fluid inlet 14a and the second fluid outlet 14b are arranged on different sides and / or second walls of the second container body. For example, the second fluid inlet 14a and the second fluid outlet 14b may be arranged obliquely (e.g., perpendicularly) to each other.

[0088] Therefore, the hollow optical fiber 16 can fluidly connect the first fluid outlet 12b of the first fluid container 12 to the second fluid inlet 14a of the second fluid container 14. The hollow optical fiber 16 can be at least partially housed and / or arranged in the first fluid outlet 12b and the second fluid inlet 14a.

[0089] For example, the optical fiber device 10 and / or the hollow optical fiber 16 may include a first coupling element 18, in which a first end 16a of the hollow optical fiber 16 is housed, and the hollow optical fiber 16 is secured to a first fluid outlet 12b via the first coupling element 18 (e.g., pressure-sealed). Preferably, at least one first sealing element (e.g., a resiliently deformable sealing tube) (e.g., radially) is arranged between the first coupling element 18 and the first end 16a of the hollow optical fiber 16. In a preferred embodiment, the first coupling element 18 and the first fluid outlet 12b may be connected by a threaded connection. For this purpose, the first coupling element 18 and the first fluid outlet 12b may include mating threads. Thus, the first coupling element 18 and the first fluid outlet 12b can be interconnected by force locking and / or form locking.

[0090] Alternatively or supplementally, the optical fiber device 10 and / or the hollow optical fiber 16 may include a second coupling element 19, in which the second end 16b of the hollow optical fiber 16 is housed, and the hollow optical fiber 16 is secured to the second fluid inlet 12a via the second coupling element 19 (e.g., pressure-sealed). Preferably, at least one second sealing element (e.g., an elastically deformable sealing tube) (e.g., radially) is arranged between the second coupling element 18 and the second end 16b of the hollow optical fiber 16. In a preferred embodiment, the second coupling element 19 and the second fluid inlet 14a may be connected by a threaded connection. For this purpose, the second coupling element 19 and the second fluid inlet 14a may include mating threads. Thus, the second coupling element 19 and the second fluid inlet 14a can be interconnected by force locking and / or shape locking.

[0091] To couple a polarized light beam to the hollow fiber 16, the first fluid container 12 and / or its first container body may include a light-transmitting window 12c, which may be referred to as the "first" light-transmitting window 12c for ease of distinction. For example, the first light-transmitting window 12c may form a sidewall of the first container body and / or may be fluid-tightly embedded or integrated into one of the first wall portions of the first container body. The first light-transmitting window 12c can separate the interior of the first fluid container 12 from its exterior. The first light-transmitting window 12c may be planar.

[0092] The first light-transmitting window 12c may be transparent to at least one of UV light, IR light, and visible light. For example, the first light-transmitting window 12c may be configured such that light with wavelengths in the range of 100 nm to 2000 nm can pass through it. The first light-transmitting window 12c may be made of, for example, glass, sapphire, and / or fused silica.

[0093] The first light-transmitting window 12c can be positioned opposite the first end 16a and / or the first fluid outlet 12b of the hollow fiber 16. For example, a direct (e.g., straight) line of sight can exist between the first light-transmitting window 12c and the first end 16a and / or the first fluid outlet 12b of the hollow fiber 16. Specifically, the first light-transmitting window 12c and the first end 16a of the hollow fiber 16 can be arranged such that a polarized light beam incident on the first light-transmitting window 12c can be transmitted to the first end 16a of the hollow fiber 16 and (at least partially) coupled to the hollow fiber 16. Preferably, the first end 16a of the hollow fiber 16 is arranged perpendicular to the main extension plane of the first light-transmitting window 12c.

[0094] Alternatively or supplementally, the second fluid container 14 and / or its second container body may include a light-transmitting window 14c, which may be referred to as the "second" light-transmitting window 14c for easy distinction. For example, the second light-transmitting window 14c may form a sidewall of the second container body and / or may be fluid-tightly embedded or integrated into one of the second walls of the second container body. The second light-transmitting window 14c may space the interior of the second fluid container 14 from the exterior of the second fluid container 14.

[0095] In principle, the second light-transmitting window 14c can have the same characteristics as the first light-transmitting window 12c. For example, the second light-transmitting window 14c can also be transparent to at least one of UV light, IR light, and visible light. However, the first light-transmitting window 12c and the second light-transmitting window 14c can also differ, for example, in terms of thickness and / or material.

[0096] Preferably, the second light-transmitting window 14c is positioned opposite the second end 16b of the hollow fiber 16 and / or the second fluid inlet 14a. For example, a direct (e.g., straight) line of sight may exist between the second light-transmitting window 14c and the second end 16b of the hollow fiber 16 and / or the second fluid inlet 14a. In particular, the second light-transmitting window 14c and the second end 16b of the hollow fiber 16 may be arranged such that light emitted from the hollow fiber 16 at the second end 16b (e.g., an output beam generated by the interaction of a polarized beam with a fluid sample as it passes through the hollow fiber 16) can be transmitted to the second light-transmitting window 14c. Preferably, the second end 16b of the hollow fiber 16 is arranged perpendicular to the main extension plane of the second light-transmitting window 14c.

[0097] In summary, the hollow fiber 16 can be arranged to guide light (e.g., a polarized beam) incident on the first transparent window 12c of the first fluid container 12 to the second transparent window 14c of the second fluid container 14. As the polarized beam propagates through the hollow fiber 16, it may interact with the fluid sample introduced into the hollow fiber 16, preferably causing a change in the polarization characteristics (e.g., its polarization direction) of the polarized beam and producing an output beam with polarization characteristics different from the original polarized beam. Preferably, the hollow fiber 16 extends in a straight line between the first fluid container 12 and the second fluid container 14. For example, the first transparent window 12c, the hollow fiber 16, and the second transparent window 14c can be arranged on an imaginary straight line and / or flush with each other. However, typically, the hollow fiber 16 can be curved or coiled.

[0098] The hollow fiber 16 used in this article is a single-ring hollow fiber, preferably a twisted single-ring hollow fiber. The following will refer to... Figure 2 To provide a more detailed explanation.

[0099] Figure 2 A cross-sectional view of a single-ring hollow fiber according to one embodiment is shown. The figure shows a cross-section perpendicular to the longitudinal axis or fiber axis of the single-ring hollow fiber, wherein the longitudinal axis or fiber axis extends along the longest dimension of the single-ring hollow fiber.

[0100] The hollow optical fiber 16 may include an outer cladding region 16a, a limited number of hollow tubes 16b, and a hollow region 16c (e.g., located at the center), wherein the hollow tubes 16b are preferably thin-walled and / or hollow in structure and are fused to the interior of the outer cladding region 16a. Preferably, as Figure 2 As shown in the embodiment, the hollow fiber 16 includes (for example, exactly) five hollow tubes 16b.

[0101] A hollow tube 16b can be arranged between the hollow region 16c and the outer cladding region 16a. That is, the hollow tube 16b can be arranged around the hollow region 16c and surrounded by the outer cladding region 16a. Therefore, the radial distance between the outer cladding region 16a and the hollow region 16c can be greater than the radial distance between the hollow tube 16b and the hollow region 16c. The hollow tube 16b can be attached to the outer cladding region 16a. For example, each hollow tube 16b can be fused to the outer cladding region 16a at its respective weld point. Therefore, the outer cladding region 16a can be in direct contact with each hollow tube 16b.

[0102] The outer cladding region 16a can be cylindrical or tubular and / or extend continuously along a longitudinal axis or an optical fiber axis. The outer cladding region 16a can be made of fused silica glass and / or soft glass. The cross-section (e.g., perpendicular to the longitudinal axis or the optical fiber axis) of the outer cladding region 16a can be circular. In this case, the thickness T (e.g., perpendicular to the longitudinal axis or the optical fiber axis) of the outer cladding region 16a can be at least 20 µm, preferably at least 70 µm, and particularly preferably at least 150 µm. The outer cladding region 16a can externally define the boundary of the hollow-core optical fiber 16.

[0103] The hollow tubes 16b can each be cylindrical or tubular and / or extend continuously along a longitudinal axis or an optical fiber axis. The hollow tubes 16b can form (e.g., a single) ring around the hollow-core region 16c. The hollow tubes 16b can be arranged (e.g., concentrically) around the hollow-core region 16c and / or each have a substantially circular cross-section. The hollow tubes 16b can be made of fused silica glass and / or soft glass. The hollow tubes 16b may not contact each other, and thus can be referred to herein as non-contact hollow tubes. Therefore, a single-ring hollow-core optical fiber can also be referred to as a revolver-type hollow-core optical fiber.

[0104] As Figure 2 shown, each hollow tube 16b can have an (e.g., average) inner tube diameter d. Additionally, as Figure 2 defined, the hollow-core region 16c can have an (e.g., average) core diameter D. Preferably, the core diameter D of the hollow-core region 16c is 10 µm < D ≤ 20 µm. Additionally or alternatively, the ratio of the inner tube diameter d of each hollow tube 16b to the core diameter D can be d / D = 0.7 and / or within the range of 0.66 to 0.73. Each hollow tube 16b can have an (e.g., average) wall thickness t. For example, the wall thickness t of each hollow tube 16b is between 100 nm and 1 µm, preferably between 200 nm and 800 nm, and particularly preferably between 300 nm and 750 nm. As Figure 2 shown in the embodiment of, the hollow tubes 16b can be identical and / or symmetrically arranged around the hollow-core region 16c. The hollow tubes 16b can be equidistantly arranged around the hollow-core region 16c. Additionally, each hollow tube 16b can have no nested sub-tubes.

[0105] In a preferred embodiment, as Figure 3As shown, the hollow fiber 16 is a twisted hollow fiber. In this configuration, the hollow tube 16b may spirally surround the hollow region 16c along the longitudinal axis or the fiber axis. Each hollow tube 16b may have a spiral twisted shape along the longitudinal axis or the fiber axis. For example, the twist rate of the twisted hollow fiber may be between 10 rad / m and 300 rad / m, preferably between 30 rad / m and 200 rad / m, and particularly preferably between 50 rad / m and 150 rad / m.

[0106] In an exemplary embodiment, the hollow fiber 16 may have the following characteristics: the hollow fiber 16 may be twisted along its length with a twist rate α = 157 rad / m. The core diameter of the hollow fiber 16 may be D = 20 µm, and the core is surrounded by five glass hollow tubes 16b, the inner diameter of which is d = 14 µm and the wall thickness is t = 670 nm. The selected ratio of inner diameter to core diameter, d / D = 0.7, preferably ensures high loss for higher-order modes, and for the selected t, the fiber preferably exhibits a low-loss transmission window from approximately 430 nm to approximately 610 nm when filled with water. The transmission window may be defined by the spectral anti-crossing phenomenon between the guided mode and the capillary wall resonance, which affects the waveguide loss and dispersion and occurs at the following wavelengths:

[0107]

[0108] Where m is a positive integer, n Si and n CO The refractive index is that of the quartz glass and the fiber core. This specific embodiment may be referred to as the test fiber below.

[0109] refer to Figure 4 and Figure 5 The following will describe the optical system 100 and the method for optical measurement of fluid samples using the optical system 100.

[0110] Optical system 100 includes the fiber optic device 10 described herein, for example... Figure 1 The optical fiber device 10 is shown. The optical system 100 also includes a polarization source device 20 and a polarization detection device 30. Optionally, the optical system 100 may also include at least one focusing element 40 and / or at least one collimating element 50.

[0111] The polarization light source device 20 can be configured and arranged to generate a polarized light beam (e.g., the wavelength of which is between 100 nm and 1000 nm) incident on a (e.g., first) light-transmitting window 12c of a first fluid container 12. For example, the polarization light source device 20 may include a light source 22 configured to generate the light beam, such as a laser source. The light beam may already be polarized. Alternatively, the light beam may be unpolarized. The polarization light source device 20 may also include a polarizer 24 (e.g., a linear polarizer) arranged to polarize the generated light beam to produce a polarized light beam. For example, the polarizer 24 may be a (e.g., an absorption type and / or a beam-splitting type) linear polarizer and / or include a half-wave plate and / or a quarter-wave plate. In summary, the polarization light source device 20 can be configured to emit a polarized light beam in a well-defined polarization state, wherein the polarized light beam is preferably a linearly polarized light beam.

[0112] To increase the amount of light coupled to the hollow fiber 16, at least one focusing element 40 can be arranged in the optical path between the polarization light source device 20 and the (e.g., first) light-transmitting window 12c of the first fluid container 12. For example, at least one focusing element 40 may include a focusing lens, a focusing mirror, and / or a focusing metamaterial structure. At least one focusing element 40 may be arranged and / or configured to focus the polarized beam generated by the polarization light source device 20 onto the (e.g., first) light-transmitting window 12c of the first fluid container 12 and / or the first end of the hollow fiber 16.

[0113] Therefore, the optical system 100 is capable of reliably coupling the polarized beam generated by the polarization light source device 20 into the hollow fiber 16. Advantageously, this can be used to measure the optical rotation and / or circular dichroism of a fluid sample, wherein, in the first step S1, the fluid sample is introduced into the hollow fiber 16 via the fiber optic device 10. For example, the fluid sample can be pumped or forced into the first fluid container 12 through an inlet 12a (e.g., the first inlet), then flow from the first fluid container 12 into the hollow fiber 16, and then from the hollow fiber 16 into the second fluid container 14, until the hollow fiber 16 is completely filled with the fluid sample. For example, after the fluid sample is introduced, it can be arranged in the hollow region 16c and / or the hollow tube 16b.

[0114] In the next step S2, the polarized light beam generated by the polarization light source device 20 passes through the hollow fiber 16 and the fluid sample introduced into the hollow fiber 16. As described above, this can be achieved by coupling the preferably focused polarized light beam through a (e.g., first) light-transmitting window 12c of the first fluid container 12 to the first end of the hollow fiber 16. The passage of the polarized light beam through the hollow fiber 16 and the fluid sample may include the polarized light beam propagating from the first end of the hollow fiber 16 to the second end of the hollow fiber 16.

[0115] As the beam passes through the hollow fiber 16 and the fluid sample, in the next step S3, the polarization characteristics of the polarized beam are altered due to the interaction between the polarized beam and the fluid sample to generate an output beam. For example, the polarization direction and / or polarization state of the polarized beam may be altered due to the interaction between the polarized beam and the electronic structure of ions or molecules in the fluid sample. The output beam can be guided by the hollow fiber 16 to its second end, exit the hollow fiber 16, and exit the fiber optic device 10 through the (e.g., second) light-transmitting window 14c of the second fluid container 14.

[0116] In the next step S4, the polarization state of the fluid sample is measured by the polarization detection device 30, preferably by comparing the polarization characteristics of the polarized beam and the output beam. For this purpose, the polarization detection device 30 may be arranged to receive the output beam emitted from the (e.g., second) light-transmitting window 14c of the second fluid container 14, and may be configured to generate an output signal depending on the polarization state of the received output beam. For example, the polarization detection device 30 may include an analyzer 32 and a photodetector 34. The analyzer 32 may be a linear analyzer (e.g., absorption type and / or beam-splitting type) and / or include a polarizing prism. The analyzer 32 is rotatable, particularly by a specific rotation angle relative to the polarizer 24 of the polarization source device 20 and / or the polarization direction of the polarized beam. The photodetector 34 may be configured to receive the detection beam and generate an output signal based on the intensity, power, energy, and / or wavelength of the received detection beam. For example, the photodetector 34 may include a CCD, a CMOS device, a phototransistor, and / or a photodiode. For example, by plotting the relationship between the output signal and the rotation angle, the angle of rotation of the polarization plane of the polarized beam caused by the interaction with the fluid sample can be determined.

[0117] To optimally utilize the detection surfaces of the polarization detection device 30 and / or photodetector 34, at least one collimating element 50 can be arranged in the optical path between the (e.g., second) light-transmitting window 14c of the second fluid container 14 and the analyzer 32. The at least one collimating element 50 may include a collimating lens, a collimating mirror, and / or a collimating metamaterial structure. The at least one collimating element 50 may be arranged to collimate the output beam before it reaches the analyzer 32.

[0118] refer to Figure 6 An exemplary apparatus for characterizing the aforementioned test optical fiber is described, wherein the apparatus may optionally include a component for measuring helical dichroism.

[0119] In this configuration, the end or end face of the test fiber is placed in the first and second fluid containers 12 and 14, respectively. To achieve coupled input and output of light, the (e.g., first) light-transmitting window 12c of the first fluid container 12 and the (e.g., second) light-transmitting window 14c of the second fluid container 14 are made of fused silica. Distilled water is injected into the test fiber using a syringe with a particulate filter. However, other fluid samples can also be used. The light source 22 of the polarization source device 20 is a supercontinuum spectrum with a spectral range down to approximately 500 nm, obtained by pumping a tapered solid-core photonic crystal fiber with nanosecond pulses emitted from a Q-switched laser (7 µJ / pulse, 1030 nm, 500 Hz).

[0120] To control topological charge To measure the possible helical dichroism of the circularly polarized chirality s, a combination of a quarter-wave plate 62, a vortex retarder 63 (the standard type of ARCoptix helical wave plate), and a half-wave plate 64 can be used. For example... Figure 4 As shown, a vortex retarder is not required when measuring optical rotation and / or circular dichroism, and the light does not need to carry topological charge. Furthermore, a bandpass filter 61 with a full width at half maximum (FWHM) of 10 nm and center wavelengths of 520 nm, 550 nm, and 580 nm is used to select narrow bands in the spectrum. The delay of the vortex retarder 63 can be adjusted for each wavelength by regulating the driving voltage (ARCoptix LC driver). When the vortex retarder 63 is adjusted to a π phase shift, the topological charge... The combination of ±1 and circular polarization (CP) chirality s=±1 produces four different vortex beams: selected by rotating a quarter-wave plate 62 (with the fast axis at ±45 degrees relative to polarizer 24). After the sign, the sign of s is changed by moving the half-wave plate 64 into or out of the beam path. For the fundamental mode ( Transmission measurement of (=0), adjust the driving voltage of vortex delayer 63 to make the phase shift 2π.

[0121] A polarized beam is directed through at least one focusing element 40, configured as an achromatic lens (focal length 5 cm), into a water-filled test fiber. The output beam is then collimated using at least one collimating element 50, configured as a second lens (focal length 3 cm), and subsequently determined. To this end, a cylindrical lens 65 (focal length 30 cm), followed by a neutral density filter 66 to maximize dynamic range, and a beam analyzer 67 are used. This allows the camera image and / or intensity pattern at the focal point of the cylindrical lens to be determined, thereby characterizing the mode field at the test fiber end face. Similarly, from Figure 4 As can be seen, topological charges are not excited / measured when measuring optical rotation and / or circular dichroism. Therefore, cylindrical lenses are not required.

[0122] refer to Figure 7 The document describes an exemplary optical system 100 capable of accurately characterizing guided wavelight and measuring its helical dichroism. Specifically, the exemplary optical system 100 can be used to acquire near-field maps of intensity and near-field maps of the normalized absolute values ​​of the S3 Stokes parameters. Figure 7 The optical system 100 and Figure 6 The difference in the device lies in the omission of the cylindrical lens 65, neutral density filter 66, and beam analyzer 67. Instead, a polarizer 32 constructed as a Wollaston prism, an achromatic lens 68, a neutral density filter 69, and a photodetector 34 constructed as a synchronous camera are used. This allows the determination of the relative intensity and the near-field plot of |S3|. For the test fiber, the near-field plot shows that the light intensity in the cladding region 16a accounts for 4.2% under weak attenuation and 32% under high loss. Since the cladding region 16a acts as a non-polarisation-maintaining highly multimode waveguide, any light coupled into it arrives at the end face with a highly mixed polarization state. To avoid introducing system measurement errors, by ignoring this light in the cladding region 16a, the average value of |S3| (weighted by intensity and averaged over the entire liquid-filled region) can be obtained: greater than 0.99 under weak attenuation and greater than 0.97 under high loss.

[0123] By replacing the synchronous camera with a laser power meter (Ophir NovaII / PD300-UV, averaging 10 seconds), each polarized beam can be measured. The fiber transmission rate and s were measured. The results show that the test fiber exhibits strong and broadband helical dichroism: for each of the three wavelengths, the transmission rate of the vortex mode injected into the test fiber increases with s. A change in sign can produce a difference of at least 10 dB. This is due to the weak attenuation of the + sign. The pattern masks the highly attenuating mode, making it impossible to obtain the actual attenuation difference from the measured transmission rate. No significant dependence of the transmission rate on the s-symbol was observed.

[0124] In summary, by using a 25cm long twisted single-ring hollow test fiber, strong and broadband helical dichroism (HD) can be measured in the visible spectrum, with a loss difference of at least 10dB in a spectral range exceeding 60THz.

[0125] Although the invention has been described with reference to specific exemplary embodiments, it will be apparent to those skilled in the art that various modifications and equivalents can be made without departing from the scope of the invention. Therefore, the invention is not limited to the disclosed exemplary embodiments, but covers all exemplary embodiments falling within the scope of the appended claims. More specifically, the invention also claims protection for the subject matter and features of dependent claims independent of the referenced claims.

Claims

1. An optical fiber device (10) for an optical system (100), comprising: A first fluid container (12) having a fluid inlet (12a), a fluid outlet (12b) and a light-transmitting window (12c); A second fluid container (14) having a fluid inlet (14a), a fluid outlet (14b) and a light-transmitting window (14c); A hollow-core optical fiber (16) fluidly connecting the fluid outlet (12b) of the first fluid container (12) to the fluid inlet (14a) of the second fluid container (14) and arranged to guide light incident on the light-transmitting window (12c) of the first fluid container (12) to the light-transmitting window (14c) of the second fluid container (14); Wherein, the hollow-core optical fiber (16) is a single-ring hollow-core optical fiber, preferably a twisted single-ring hollow-core optical fiber.

2. The optical fiber device (10) according to claim 1, wherein: The first fluid container (12) and the second fluid container (14) are arranged at opposite ends of the hollow-core optical fiber (16); The hollow-core optical fiber (16) includes a plurality of individual fluid passages (17), each fluid passage configured to transport a fluid sample between the first fluid container (12) and the second fluid container (14); and / or The length of the hollow-core optical fiber (16) is between 1 cm and 2 m, preferably between 5 cm and 50 cm, particularly preferably between 10 cm and 30 cm.

3. The optical fiber device (10) according to claim 1 or 2, wherein, The hollow-core optical fiber (16) includes: An outer cladding region (16a); and A hollow tube (16b), preferably five hollow tubes (16b), the hollow tubes being surrounded by the outer cladding region (16a), wherein each hollow tube (16b) is fused to the outer cladding region (16a) to form a ring around the hollow region (16c) of the hollow-core optical fiber (16).

4. The optical fiber device (10) according to claim 3, wherein: The hollow-core optical fiber (16) includes exactly five hollow tubes (16b); Each hollow tube (16b) has a circular cross-section; and / or The hollow tubes (16b) do not contact each other; and / or The hollow tubes (16b) are symmetrically arranged around the hollow region (16c); and / or Each hollow tube (16b) has no nested sub-tubes.

5. The optical fiber device (10) according to claim 3 or 4, wherein: The core diameter D of the hollow region (16c) satisfies: 10 μm < D and / or D ≤ 20 µm; and / or Each hollow tube (16b) has an inner tube diameter d, wherein the ratio of the inner tube diameter to the core diameter d / D satisfies 0.66 < d / D < 0.73, and / or, wherein the inner tube diameter is less than the core diameter, d < D; The high-order mode (HOM) suppression ability of the hollow-core optical fiber (16) is at least 40 dB / m, preferably at least 70 dB / m, particularly preferably at least 110 dB / m; and / or The hollow optical fiber (16) is a twisted hollow optical fiber with a twist rate α between 10 rad / m and 300 rad / m, preferably between 30 rad / m and 200 rad / m, and particularly preferably between 50 rad / m and 150 rad / m; and / or The wall thickness t of each hollow tube (16b) is between 100 nm and 1 μm, preferably between 200 nm and 800 nm, and particularly preferably between 300 nm and 750 nm.

6. The optical fiber device (10) according to any one of claims 3 to 5, wherein: The outer cladding region (16a) directly contacts each of the hollow tubes (16b); and / or Each of the hollow tubes (16b) is attached to the outer sheath region (16a); and / or The thickness T of the outer cladding region (16a) is at least 20 μm, preferably at least 70 μm, and particularly preferably at least 150 μm; and / or The outer cladding region (16a) and / or the hollow tube (16b) are made of fused silica glass and / or soft glass.

7. The optical fiber device (10) according to any one of the preceding claims, wherein: The light-transmitting window (12c) of the first fluid container (12) is arranged opposite to and / or flush with the fluid outlet (12b) of the first fluid container (12); and / or The light-transmitting window (14c) of the second fluid container (14) is arranged opposite to and / or flush with the fluid inlet (14a) of the second fluid container (14); and / or The fluid inlet (12a) and the fluid outlet (12b) of the first fluid container (12) are arranged obliquely to each other, preferably perpendicularly to each other; and / or The fluid inlet (14a) and fluid outlet (14b) of the second fluid container (14) are arranged obliquely to each other, preferably perpendicularly to each other; and / or The hollow optical fiber (16) extends in a straight line between the first fluid container (12) and the second fluid container (14).

8. The optical fiber device (10) according to any one of the preceding claims, further comprising: The first coupling element (18), preferably a collar, wherein the first end (16a) of the hollow optical fiber (16) is accommodated in the first coupling element (18), and Wherein, the hollow optical fiber (16) is fixed to the first fluid container (12) by the first coupling element (18), preferably by force locking and / or shape locking, preferably by pressure sealing; and / or The second coupling element (19), preferably a collar, wherein the second end (16b) of the hollow optical fiber (16) is accommodated in the second coupling element (19), and wherein the hollow optical fiber (16) is fixed to the second fluid container (14) by the second coupling element (19), preferably by force locking and / or shape locking, preferably by pressure sealing.

9. The optical fiber device (10) according to any one of the preceding claims, wherein: The hollow optical fiber (16) is detachably connected to the first fluid container (12) and / or the second fluid container (14); or The hollow optical fiber (16), the first fluid container (12), and the second fluid container (14) are integrally connected to each other to form a single unit.

10. An optical system (100) for optical measurement, preferably used for measuring the optical rotation and / or circular dichroism and / or spiral dichroism of a fluid sample, comprising: The optical fiber device (10) according to any one of the preceding claims; A polarization light source device (20) is constructed and arranged to generate a polarized light beam incident on the light-transmitting window (12c) of the first fluid container (12); A polarization detection device (30) is arranged to receive an output beam emitted from the light-transmitting window (14c) of the second fluid container (14) and is configured to generate an output signal that depends on the polarization state of the received output beam.

11. The optical system (100) according to claim 10, wherein: The polarized beam is a linearly polarized beam or a circularly polarized beam; and / or The wavelength of the polarized beam is between 100 nm and 2000 nm, preferably between 200 nm and 1000 nm, and particularly preferably between 400 nm and 600 nm; and / or The polarizing light source device (20) is directly attached to the light-transmitting window (12c) of the first fluid container (12), and / or is arranged to be directly adjacent to the light-transmitting window (12c) of the first fluid container (12), and / or is supported by the light-transmitting window (12c) of the first fluid container (12); and / or the polarizing light source device (20) includes: The light source (22), preferably a laser light source, is configured to generate a light beam; and A polarizer (24), preferably a linear polarizer, is arranged to polarize the resulting beam to produce a polarized beam.

12. The optical system (100) according to claim 10 or 11, wherein: The polarization detection device (30) includes: A rotatable and / or rotating analyzer (32), preferably a linear analyzer, is arranged to polarize the output beam to generate a polarization detection beam; and A photodetector (34) is configured to receive a detection beam and generate the output signal based on the intensity, power, energy and / or wavelength of the received detection beam.

13. The optical system (100) according to any one of claims 10 to 12, further comprising: At least one focusing element (40), preferably comprising a focusing lens, a focusing mirror, and / or a focusing metamaterial structure, said at least one focusing element being arranged to focus the generated polarized beam onto the light-transmitting window (12c) of the first fluid container (12); and / or At least one collimating element (50), preferably comprising a collimating lens, a collimating mirror and / or a collimating metamaterial structure, is arranged to collimate the output beam before the output beam enters the polarization detection device (30).

14. An optical measurement method, preferably used for measuring the optical rotation and / or circular dichroism and / or spiral dichroism of a fluid sample, and particularly preferably using an optical system (100) according to any one of claims 10 to 13, wherein, The method includes: A fluid sample is introduced into a hollow optical fiber (16), preferably through an optical fiber device (10), wherein the hollow optical fiber (16) is a single-ring hollow optical fiber, preferably a twisted single-ring hollow optical fiber. A polarized beam is passed through the hollow fiber (16) and a fluid sample introduced into the hollow fiber (16), the polarized beam preferably being generated by a polarization light source device (20); As the polarized beam passes through the hollow fiber (16) and the fluid sample, its polarization characteristics are altered through interaction with the fluid sample to generate an output beam; and The polarization state of the generated output beam is measured by comparing the polarization characteristics of the polarized beam and the output beam, preferably by a polarization detection device (30).

15. The method of claim 14, wherein: The fluid sample is a liquid; and / or The fluid sample contains at least one chiral molecule and / or at least one chiral ion; and / or The fluid sample contains at least one enantiomer.

16. The method according to claim 14 or 15, wherein: The introduction step includes sequentially pressurizing the fluid sample through the following components: the inlet (12a) of the first fluid container (12), the hollow optical fiber (16) fluidly connected to the outlet (12b) of the first fluid container (12), the inlet (14a) of the second fluid container (12) fluidly connected to the hollow optical fiber (16), and the outlet (14b) of the second fluid container (14).

17. The method according to any one of claims 14 to 16, wherein: When the polarized beam passes through the hollow fiber (16) and the fluid sample introduced into the hollow fiber (16): The fluid sample flows through the hollow optical fiber (16), preferably continuously; or The fluid sample is static and / or does not flow through the hollow fiber (16).

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