Radiation source unit for carrying out an optical measurement, optical measuring system and method for producing a radiation source unit

Abstract

A radiation source unit (10) for carrying out an optical measurement has a radiation source (12), an optical conductor (13) for guiding radiation generated by the radiation source (12), and a substrate (16). The optical conductor (13) is designed to conduct a propagating mode. The radiation source unit (10) has a reference measuring device (14, 15) for carrying out a reference measurement, by means of which a change in a spectral characteristic of the radiation source (12) can be detected. The reference measuring device (14, 15) has a wavelength reference (14) which is arranged along at least one part of the optical conductor (13) in such a way that an evanescent field of the propagating mode enters the wavelength reference (14).

Description

[0001] Radiation source unit for performing an optical measurement, optical measuring system and method for producing a radiation source unit

[0002] TECHNICAL FIELD

[0003] The invention relates to devices and systems for performing measurements using electromagnetic radiation. In particular, the invention relates to such devices and systems that are configured to determine spectral characteristics of a radiation source and use them to perform the measurement. The invention also relates to manufacturing methods configured for manufacturing such devices and systems.

[0004] BACKGROUND

[0005] In optical measurement methods, a measurement is performed through the interaction of electromagnetic radiation with an object. It is important that the radiation pattern of the radiation source used can be traced back to a wavelength standard. Calibration and traceability of the radiation pattern to wavelength standards enables accurate and reliable measurements.

[0006] Precise measurement is particularly important in fields such as spectroscopy, colorimetry, and industrial metrology. Deviations in the radiation pattern can lead to measurement errors and affect the accuracy and reproducibility of the measurement results. Furthermore, tracing the radiation pattern to wavelength standards enables comparability of measurement results between different measurement systems.

[0007] US 10 527 784 B1, US 2019 / 0011639 A1, and US 2022 / 0370010 A1 disclose devices for performing optical measurements. Devices with integrated wavelength references offer advantages in terms of the meaningfulness of the measurement results, as they can account for unintentional changes in the radiation characteristics of the radiation source.

[0008] Various techniques exist for determining the radiation characteristics of a radiation source and relating them to a wavelength standard. These include, for example, gas cells, the use of an interferometer, and the application of solid-state wavelength standards. The latter offer various advantages in terms of their manageability, simplicity, and application-specific adaptability. There continues to be a need in technology for improved devices, systems, and methods designed to detect the radiation characteristics of a radiation source intended for performing an optical measurement.

[0009] SUMMARY

[0010] The invention is based on the object of providing improved devices, systems, and methods designed to detect a radiation characteristic of a radiation source intended for performing an optical measurement. In particular, the invention is based on the object of providing devices, systems, and methods that enable the measurement of the radiation characteristic of the radiation source using a compact, robust, and / or efficiently manufactured design of components for reference measurement.

[0011] According to the invention, a device, a system, and a method are provided as defined in the independent claims. The dependent claims define preferred and advantageous embodiments.

[0012] According to one aspect, the invention relates to a radiation source unit for performing an optical measurement. The radiation source unit comprises: a radiation source; an optical guide for guiding radiation generated by the radiation source, wherein the optical guide is configured to guide a propagating mode; a substrate on which the radiation source and the optical guide are arranged; and a reference measuring device for performing a reference measurement with which a change in a spectral characteristic of the radiation source can be detected. The reference measuring device comprises a wavelength reference arranged along at least part of the optical guide such that an evanescent field of the propagating mode enters the wavelength reference.

[0013] The radiation source unit offers several technical advantages and effects. The arrangement of the wavelength reference allows the spectral characteristics of the radiation source to be determined based on the interaction of the evanescent field with the wavelength reference. This allows the reference measuring device to detect changes, such as drift, in the spectral characteristics of the radiation source. Furthermore, the arrangement of the wavelength reference such that the evanescent field of the propagating mode enters the wavelength reference offers process-related advantages, for example, during assembly of the wavelength reference. The radiation source unit has the reference measuring device integrated therein, which facilitates the continuous (e.g., repeated) measurement of the spectral characteristics of the radiation source.

[0014] The optical conductor may have a cladding. The wavelength reference may be

[0015] The cladding can be arranged adjacent to the cladding. This allows the wavelength reference to be mechanically supported in a simple manner and also allows the evanescent field to enter the wavelength reference.

[0016] The optical conductor may have a core and a cladding. The wavelength reference may be arranged adjacent to the core.

[0017] This allows the wavelength reference to be mechanically supported in a simple manner and also allows the evanescent field to enter the wavelength reference.

[0018] The cladding may include the wavelength reference in at least one portion of the cladding, for example as an integral part of the cladding.

[0019] This allows the wavelength reference to be mechanically supported in a simple manner and, in addition, a particularly simple construction allows the evanescent field to enter the wavelength reference.

[0020] The optical conductor may have a core and optionally a cladding. The core may contain the wavelength reference. In other words, the wavelength reference may also be structurally integrated into the core.

[0021] This allows the field to enter the wavelength reference with a simple structure.

[0022] The wavelength reference may comprise a solid-state wavelength reference.

[0023] This allows the radiation source unit to be manufactured easily. The solid-state wavelength reference can be mounted as a unit on the optical fiber cladding or printed onto it.

[0024] The solid-state wavelength reference can be a solid-state standard.

[0025] This allows for a simple manufacturing of the radiation source unit. The solid-state standard can be mounted as a unit on the optical conductor's sheath.

[0026] The solid-state standard can have a body made of a plastic material, such as PTFE (polytetrafluoroethylene). The solid-state standard can be used to enable precise and reliable measurements. PTFE standards can be manufactured in the form of plates or foils.

[0027] This allows a reference measurement to be carried out using an easy-to-use, robust and time-stable wavelength reference.

[0028] The solid-state standard can comprise a matrix made of a plastic material (e.g., comprising PTFE). The solid-state standard can optionally contain one or more dopings, which can be application-specific. This allows the reference measurement to be performed using an easy-to-handle, robust, and time-stable wavelength reference, which can be easily selected for the specific application.

[0029] The solid-state standard may comprise a plastic material with at least one dopant or multiple dopants.

[0030] This allows the desired properties of the wavelength reference to be achieved for a specific application. For example, a specific doping can be incorporated into the plastic material of the solid-state standard to achieve specific absorption and / or reflection characteristics. This doping can improve the sensitivity, accuracy, and reproducibility of the measurement system using the radiation source unit.

[0031] The at least one dopant or the plurality of dopants may comprise nitrogen.

[0032] This allows the desired properties of the wavelength reference to be achieved for a specific application. The sensitivity, accuracy, and reproducibility of the measurement system using the radiation source unit can be improved.

[0033] The reference measuring device can comprise at least one detector arranged on the substrate. The at least one detector can be coupled to the optical conductor and configured to detect an optical measurement variable (e.g., absorption or reflection) of the wavelength reference. The detector can be configured to detect the optical measurement variable (e.g., absorption or reflection) of the wavelength reference for multiple wavelengths in a wavelength-resolved manner.

[0034] This allows the interaction of the evanescent field with the wavelength reference to be recorded and used, for example, to detect a change in a spectral characteristic of the radiation source. By integrating the at least one detector on the substrate, a unit with an integrated measuring device can be provided, which is configured to detect a change in the spectral characteristic of the radiation source (for example, as a function of time and / or relative to a target spectral characteristic).

[0035] The detector may be arranged and configured to detect the propagating mode after its evanescent field has interacted with the wavelength reference as it passes through the optical guide.

[0036] This allows the interaction of the evanescent field with the wavelength reference to be recorded and used, for example, to detect a change in a spectral characteristic of the radiation source.

[0037] The radiation source unit can be configured to control or regulate the radiation source depending on the optical measurement variable (for example the wavelength-dependent absorption and / or reflection) of the wavelength reference detected by the detector in order to track the spectral characteristic.

[0038] This allows the radiation source to be controlled or regulated such that it emits radiation with a defined spectral characteristic. The radiation source unit can be configured to control or regulate the radiation source such that a change (e.g., a drift) in the spectral characteristic detected using the wavelength reference is at least partially compensated.

[0039] Alternatively or additionally, the radiation source unit can be configured to provide output data dependent on the optical measurement quantity for a computational compensation of the spectral characteristics of the radiation source.

[0040] As a result, the radiation source unit is configured to provide the data or signals required for a correction to compensate for a change (e.g., a drift) in the spectral characteristic detected using the wavelength reference.

[0041] The radiation source unit may comprise a chip containing a gain material of the radiation source. The detector may comprise at least a portion of the gain material of the radiation source.

[0042] This enables particularly efficient measurement of changes in the spectral characteristics of the radiation source. The gain material of the same chip can act both to generate the radiation and as the sensitive material of the detector.

[0043] The radiation source unit can have at least one further optical guide. Each further optical guide of the at least one further optical guide can be configured to guide at least one further propagating mode. The radiation source unit can have at least one further wavelength reference arranged such that an evanescent field of the at least one further propagating mode enters the at least one further wavelength reference. The at least one further wavelength reference can have different optical properties than the wavelength reference.

[0044] In this way, changes in the spectral characteristics of the radiation source can be detected particularly reliably using the wavelength reference and the at least one further wavelength reference.

[0045] The radiation source unit may comprise a combiner coupled to the optical conductor and the at least one further optical conductor. The combiner may be configured to feed the mode propagating through the optical conductor or the further mode propagating through the further optical conductor to a detection device.

[0046] This achieves an efficient design. For example, detection after interaction with different wavelength references can be performed by the same detector. The radiation source unit can have a splitter coupled to the optical conductor and the at least one further optical conductor. The splitter can be configured to couple the radiation into at least one of the optical conductor and the further optical conductor.

[0047] This allows for an efficient design. For example, the radiation generated by the radiation source can be directed through the splitter for calibration (i.e., to determine whether there is a change in the spectral characteristics) so that it can interact with different wavelength references via the evanescent field.

[0048] The radiation source unit may comprise at least one further detector configured to detect radiation generated by the radiation source after interaction with a further wavelength reference of the at least one further wavelength reference.

[0049] This allows the interaction of the evanescent field to be captured after passing through the different optical guides, each of which carries different wavelength references. Parallel acquisition is possible, thus reducing the time required for the reference measurement.

[0050] The radiation source unit may comprise at least one additional radiation source. The radiation source unit may be configured to selectively output radiation generated by the radiation source or the additional radiation source via a sample interface of the radiation source unit.

[0051] This allows the spectral characteristics of several different radiation sources to be used to carry out the optical measurement.

[0052] The radiation source unit may comprise an additional group of one or more additional optical guides, each of which has an additional wavelength reference arranged thereon. The additional optical guide(s) may be arranged such that an evanescent field of the mode propagating therein can interact with the additional wavelength reference arranged on the additional optical guide. The radiation source unit may comprise at least one additional detector configured to detect the radiation generated by the additional radiation source after interaction with at least one of the additional wavelength references.

[0053] This allows the radiation source unit to perform a reference measurement for detecting a change in the spectral characteristic of the additional radiation source. The radiation source unit can be configured to output information about the detected change via a data or signal interface for use in computational compensation and / or to control or regulate the additional radiation source based thereon. The radiation source unit can comprise a first chip comprising the radiation source and the detector, and a second chip comprising the additional radiation source and the additional detector. The first chip and the second chip are mounted on the substrate. The first chip can comprise a first gain material used by the radiation source and the detector, and the second chip can comprise a second gain material used by the additional radiation source and the additional detector.

[0054] This allows the various radiation sources and detectors to be implemented in an efficient manner.

[0055] The radiation source unit can comprise an optical multiplexer and / or an optical demultiplexer. The radiation source unit can be configured to control the optical multiplexer and / or the optical demultiplexer such that radiation from different radiation sources can be selectively output via a sample interface and / or can interact with at least one wavelength reference to perform a reference measurement.

[0056] This allows the spectral characteristics of different radiation sources to be used to carry out the optical measurement, whereby the radiation source unit detects changes in the spectral characteristics of the different radiation sources and provides appropriate compensation mechanisms.

[0057] The radiation source unit may include a controller for controlling the combiner and / or the splitter. The controller may optionally also be configured to control the optical multiplexer and / or the optical demultiplexer.

[0058] This allows the combiner and / or the splitter (and, if present, multiplexer and / or demultiplexer) to be controlled under the control of the controller in such a way that a change in the spectral characteristics of the radiation source can be detected in a systematic manner using the different wavelength references.

[0059] The optical guide may have at least one curved section in which an axis of the optical guide has a curvature. The wavelength reference may be arranged on the at least one curved section.

[0060] By locating the wavelength reference at the curved section, the length over which the evanescent field of the mode propagating in the optical guide can interact with the wavelength reference can be increased while maintaining a compact design. This enables particularly reliable detection of changes in the spectral characteristics of the radiation source.

[0061] The at least one curved section may have a two-dimensional spiral and / or meandering geometry. The two-dimensional spiral and / or meandering

[0062] The geometry can extend parallel to a substrate plane. This geometry allows for a compact design to increase the length over which the evanescent field of the mode propagating in the optical guide can interact with the wavelength reference. This enables particularly reliable detection of a change in the spectral characteristics of the radiation source.

[0063] The wavelength reference can cover the two-dimensional spiral and / or meandering geometry.

[0064] This allows the length over which the evanescent field of the mode propagating in the optical guide can interact with the wavelength reference to be increased using an easily manufactured configuration of the radiation source unit. This enables particularly reliable detection of a change in the spectral characteristics of the radiation source.

[0065] The radiation source unit may be configured such that a photonic integrated circuit comprises the substrate, the radiation source and the optical conductor.

[0066] As a result, the radiation source unit with an integrated wavelength reference can be provided in a simple manner by arranging the wavelength reference on the optical conductor (in particular, a sheath of the optical conductor). The wavelength reference can be arranged as a solid body on, in particular, the optical conductor.

[0067] The radiation source unit can be designed such that the photonic integrated circuit has the detector.

[0068] As a result, the radiation source unit with integrated wavelength reference can be provided in a simple manner by arranging the wavelength reference on the optical conductor (in particular a cladding of the optical conductor) of the photonic integrated circuit having the detector in order to detect a change in the spectral characteristic of the radiation source based on the interaction with the wavelength reference.

[0069] The radiation source unit can be designed such that the wavelength reference is arranged on the photonic integrated circuit via a flip-chip assembly.

[0070] This allows the radiation source unit to be manufactured in a simple and robust manner with an integrated wavelength reference.

[0071] The radiation source unit can be designed such that the wavelength reference is printed on the optical conductor.

[0072] This allows the radiation source unit to be equipped in a simple and robust manner with integrated

[0073] A wavelength reference can be manufactured. The radiation source unit can be designed such that the wavelength reference is encapsulated together with the photonic integrated circuit.

[0074] This allows the radiation source unit with integrated wavelength reference to be provided as an integral unit for use in an optical measurement system.

[0075] The radiation source unit can be designed such that the wavelength reference is detachably connected to the photonic integrated circuit in a non-destructive manner.

[0076] This allows the radiation source unit with integrated wavelength reference to be provided with a modular design. This is advantageous in terms of recyclability and / or adaptability.

[0077] The radiation source unit may have an encapsulation.

[0078] This allows the radiation source unit with integrated wavelength reference to be provided as an integral unit for use in an optical measurement system.

[0079] The encapsulation can have an interface for optically measuring the wavelength reference (optionally also, if available, several different wavelength references).

[0080] This allows the wavelength reference (optionally, if available, several different wavelength references) to be used for measurement systems separate from the radiation source unit.

[0081] The interface may have at least one measuring opening, for example a measuring window, in the encapsulation.

[0082] This enables access to the optical measurement of the wavelength reference (optionally also, if available, several different wavelength references) without requiring fiber coupling.

[0083] The interface may have at least one, advantageously at least two, fiber couplers.

[0084] This enables access for optical measurement of the wavelength reference (optionally also, if available, several different wavelength references) via a fiber coupling.

[0085] The radiation source unit can be a radiation source unit for an interferometric measuring system, a spectrometer system, a medical measuring system, a biological measuring system, an industrial measuring system.

[0086] This takes advantage of the fact that the wavelength reference(s) can be efficiently adapted for different applications and that the radiation source unit has a robust, time-stable design that makes it suitable for different applications.

[0087] The encapsulation may include a sample interface for outputting radiation to the sample. The sample interface may include output optics (e.g., one or more refractive elements) and / or a fiber coupling device. This allows the radiation provided by the radiant light source to be made available for use in performing the optical measurement.

[0088] The encapsulation may have an electrical interface for outputting signals and / or data indicating a change in the spectral characteristics of at least one radiation source detected by the reference measuring device.

[0089] This allows the result of the reference measurement to be made available using the wavelength reference for a computational compensation of the change.

[0090] The radiation source, if present, may be configured to emit radiation in the visible spectral range (for example in the range from 350 nm to 900 nm or in the range from 400 nm to 780 nm) and / or near-infrared spectral range (for example in the range from 800 nm to 2700 nm or in the range from 900 nm to 2700 nm or in the range from 900 nm to 2700 nm) and / or in the mid-infrared (MIR) spectral range (for example in the range from 1400 nm to 25 pm or in the range from 1400 nm to 10 pm or in the range from 1400 nm to 5 pm or in the range from up to 5 pm or up to 10 pm or up to 25 pm).

[0091] This allows various measurement applications to be covered, for example in the field of biological and / or medical measurement technology.

[0092] The substrate may comprise a silicon substrate.

[0093] This can reduce unwanted interactions with the substrate in relevant applications.

[0094] The reference measuring device can be configured to perform the reference measurement for detecting a change in the spectral characteristics of the radiation source(s) based on a trigger criterion. The reference measuring device can be configured to perform the reference measurement continuously during the useful operation of the radiation source unit. The trigger criterion can comprise a time-based trigger criterion. For example, using a timer, a reference measurement for detecting the change in the spectral characteristics of the radiation source(s) can be performed after a time interval has elapsed, wherein the time interval can be predefined, variable, and / or user-definable. The trigger criterion can comprise an event-based trigger criterion.For example, the reference measurement for detecting the change in the spectral characteristics of the radiation source(s) can be carried out depending on a number of uses in optical measurements on samples (e.g. sample materials and / or sample bodies) and / or depending on a user input.

[0095] As a result, the spectral characteristic can be continuously recorded and appropriately corrected during use. According to a further aspect of the invention, an optical measuring system is provided, comprising: the radiation source unit according to one aspect or embodiment, wherein the radiation source unit has a sample interface for irradiating radiation generated by the radiation source onto a sample (for example, a sample material and / or a sample body); a sample light detector for detecting sample light received by the sample; and at least one evaluation device for evaluating output signals or output data of the sample light detector.

[0096] The optical measuring system achieves the advantages and effects explained in the context of the radiation source unit.

[0097] The optical measuring system can be or comprise an interferometric measuring system, a spectrometer system, a medical measuring system, a biological measuring system, or an industrial measuring system.

[0098] This takes advantage of the fact that the wavelength reference(s) can be efficiently adapted for different applications and that the radiation source unit has a robust, time-stable design that makes it suitable for different applications.

[0099] The evaluation device can be configured to carry out a computational compensation of the spectral characteristics of the radiation source.

[0100] This allows a change in the spectral characteristics of the radiation source to be taken into account mathematically during the evaluation without the radiation source(s) necessarily having to be adjusted.

[0101] The evaluation device may have an electrical interface for receiving signals or data provided by the radiation source unit that indicate the change in the spectral characteristic detected by the reference measuring device.

[0102] As a result, the evaluation device is configured to receive the data or signals required for a correction in order to computationally compensate for a change (e.g. a drift) in the spectral characteristic that was detected using the wavelength reference.

[0103] The wavelength reference may comprise a solid-state wavelength reference.

[0104] This allows the radiation source unit to be manufactured easily. The solid-state wavelength reference can be mounted as a unit on the optical fiber cladding or printed onto it.

[0105] The solid-state wavelength reference can be a solid-state standard.

[0106] This allows the radiation source unit to be manufactured in a simple manner.

[0107] The solid-state standard can be mounted as a unit on the sheath of the optical fiber. The sample light detector can comprise an interferometer and / or a spectrometer.

[0108] This allows the optical measuring system to be used to perform interferometric and / or spectrometric measurements.

[0109] The wavelength reference may comprise a solid-state wavelength reference.

[0110] This allows the radiation source unit to be manufactured easily. The solid-state wavelength reference can be mounted as a unit on the optical fiber cladding or printed onto it.

[0111] The solid-state wavelength reference can be a solid-state standard.

[0112] This allows for a simple manufacturing of the radiation source unit. The solid-state standard can be mounted as a unit on the optical conductor's sheath.

[0113] According to a further aspect of the invention, a method for producing a radiation source unit is provided, wherein the radiation source unit comprises an integrated photonic circuit. The integrated photonic circuit comprises a radiation source, an optical guide for guiding radiation generated by the radiation source, and a substrate. The radiation source and the optical guide are arranged on the substrate. The optical guide is configured to guide a propagating mode. The method comprises: arranging a wavelength reference on the optical guide, wherein the wavelength reference is arranged along at least a portion of the optical guide such that an evanescent field of the propagating mode enters the wavelength reference.

[0114] The method offers several technical advantages and effects. The arrangement of the wavelength reference makes it possible to provide a radiation source unit configured to determine the spectral characteristics of the radiation source based on the interaction of the evanescent field with the wavelength reference. This allows the reference measuring device to detect changes, such as drift, in the spectral characteristics of the radiation source. The method offers process-related advantages, for example, during the assembly of the wavelength reference, since the wavelength reference can be easily arranged on the optical conductor of the photonic integrated circuit.

[0115] The wavelength reference may comprise a solid-state wavelength reference.

[0116] This allows the radiation source unit to be manufactured easily. The solid-state wavelength reference can be mounted as a unit on the optical fiber cladding or printed onto it.

[0117] The solid-state wavelength reference can be a solid-state standard. This allows the radiation source unit to be designed for easy manufacture.

[0118] The solid-state standard can be placed as a unit on the cladding of the optical fiber.

[0119] The method may include flip-chip mounting of the wavelength reference to the optical guide of the photonic integrated circuit.

[0120] This allows the radiation source unit to be manufactured in a simple and robust manner with an integrated wavelength reference.

[0121] The method may include printing the wavelength reference on the optical guide.

[0122] This allows the radiation source unit to be manufactured in a simple and robust manner with an integrated wavelength reference.

[0123] The method may be a method for manufacturing the radiation source unit according to an aspect or embodiment of the invention.

[0124] Further optional features of the method and the effects achieved thereby correspond to the features and effects explained with reference to the radiation source unit and the optical measuring system.

[0125] According to a further aspect of the invention, a method for examining a sample (for example sample material and / or a sample body) is provided, comprising generating radiation using the radiation source unit according to one aspect or embodiment.

[0126] According to a further aspect of the invention, a method for detecting a change in a spectral characteristic of a radiation source is provided, wherein detecting the change comprises detecting an optical measurement variable after radiation generated by the radiation source passes through an optical guide, wherein an evanescent field interacts with a solid-state wavelength reference arranged on the optical guide. The method can be carried out using the radiation source unit and / or the optical measurement system according to one aspect or embodiment.

[0127] According to a further aspect of the invention, a method for detecting a change in a spectral characteristic of a radiation source is provided, wherein detecting the change comprises detecting an optical measurement variable after radiation generated by the radiation source passes through an optical guide, wherein an evanescent field interacts with a solid-state wavelength reference arranged on the optical guide. The method can be carried out using the radiation source unit and / or the optical measurement system according to one aspect or embodiment.According to a further aspect of the invention, a method for performing an optical measurement is provided, in which requirements regarding the stability of a radiation source are relaxed and a change in a spectral characteristic of a radiation source is detected and at least partially compensated. Detecting the change comprises detecting an optical measurement variable after radiation generated by the radiation source has passed through an optical conductor, wherein an evanescent field interacts with a solid-state wavelength reference arranged on the optical conductor. The method can be carried out using the radiation source unit and / or the optical measurement system according to one aspect or embodiment.

[0128] According to a further aspect of the invention, machine-readable instruction code is provided which, when executed by a programmable computing unit, carries out the method according to one aspect or embodiment of the invention.

[0129] According to a further aspect of the invention, a storage medium is provided with machine-readable instruction code stored thereon, which, when executed by a programmable computing unit, carries out the method according to one aspect or embodiment of the invention.

[0130] The radiation source unit, the optical measurement system, and the methods provide different effects and advantages. The radiation source unit, the optical measurement system, and the methods offer a robust and easily manufactured radiation source unit with an integrated wavelength reference. The radiation source unit, the optical measurement system, and the methods are designed to detect and at least partially compensate for any changes in the spectral characteristics of the radiation source. This relaxes the requirements for the spectral stability of the radiation source, even with precisely measuring optical measurement systems.

[0131] The methods, systems, and system components can be used in various fields. These include optical measurements on biological samples and / or measurements in industrial manufacturing and / or quality control. The radiation source unit, the optical measurement system, and the methods can also be used in medical devices or medical systems.

[0132] BRIEF DESCRIPTION OF THE CHARACTERS

[0133] Embodiments of the invention are described with reference to the figures. In the figures, similar or identical reference numerals designate elements with similar or identical design and / or function.

[0134] Figure 1 is a schematic representation of a radiation source unit.

[0135] Figure 2 is a sectional view of the radiation source unit.

[0136] Figure 3 is a schematic representation of an optical measuring system that

[0137] radiation source unit. Figure 4 is a schematic representation of an optical measuring system that

[0138] radiation source unit.

[0139] Figure 5 is a schematic representation of an optical measuring system that

[0140] Radiation source unit with an additional optical system coupled thereto.

[0141] Figure 6 is a schematic representation of components of the radiation source unit.

[0142] Figure 7 is a schematic representation of components of the radiation source unit.

[0143] Figure 8 is a schematic representation of components of the radiation source unit.

[0144] Figure 9 is a schematic representation of components of the radiation source unit.

[0145] Figure 10 is a schematic representation of components of the radiation source unit.

[0146] Figure 11 is a schematic representation of components of the radiation source unit.

[0147] Figure 12 is a schematic partially exploded view of the radiation source unit.

[0148] Figure 13 is a schematic representation of components of the radiation source unit.

[0149] Figure 14 is a schematic representation of an optical measuring system that

[0150] radiation source unit.

[0151] Figure 15 is a schematic representation of an optical measuring system that

[0152] radiation source unit.

[0153] Figure 16 is a flowchart of a method for optical measurement of a sample.

[0154] Figure 17 is a flow chart of a manufacturing process.

[0155] DETAILED DESCRIPTION OF EMBODIMENTS

[0156] Embodiments of the invention are described with reference to the figures. In the figures, similar or identical reference numerals designate elements with similar or identical design and / or function.

[0157] While embodiments are described in the context of position determination in an industrial context or in medical technology, the radiation source units, systems and methods described here are not limited to these areas of application.

[0158] The features of the embodiments can be combined with each other unless this is expressly excluded in the following description.

[0159] The radiation source unit, the optical measuring system, and the methods according to embodiments enable the verification and correction of changes in the spectral characteristics of radiation sources and / or detectors using traceable wavelength standards. The radiation source unit, the optical measuring system, and the methods can be configured to correct a drift or other instability of the emission wavelength(s) of the radiation source. The radiation source(s) can be configured in particular as laser source(s). The laser source(s) can be configured as multi-wavelength laser source(s). In this context, embodiments of the invention are particularly advantageous because such radiation sources are susceptible to drift caused by temperature changes, but offer the advantage that additional detectors of a reference measuring device can be efficiently integrated for characterization and / or stabilization.In particular, integration may be such that the laser source(s) (e.g. multi-wavelength laser source(s)) and the detector(s) may be provided on a common substrate as part of a photonic integrated circuit.

[0160] It is proposed that the radiation source unit, the optical measuring system, and the methods be designed such that at least one wavelength reference is provided on a photonic integrated circuit. The wavelength reference can be designed as a wavelength standard, in particular as a solid-state wavelength standard. The radiation source unit, the optical measuring system, and the methods enable the wavelength reference to be continuously measured (e.g., continuously) during operation and, as a result, to detect a change in the spectral characteristics. A correction of the change can be realized in various ways, for example, by controlling or regulating the radiation source(s) or computationally when evaluating the optical measurements obtained on a sample (e.g., sample material and / or a sample body) using the radiation source unit.

[0161] The radiation source unit, the optical measurement system, and the methods allow for precise and traceable measurements while simultaneously placing lower demands on the stability of the radiation sources used. This facilitates the transfer of measurement results between different optical measurement systems. This makes it easier, for example, to emulate the results of other optical measurement systems.

[0162] The term "optical guide" as used here refers to a structure configured to guide electromagnetic radiation in the visible and / or near-infrared spectral range and / or mid-infrared spectral range along an axis of the optical guide, in particular from one end of the optical guide to another end of the optical guide. The optical guide can in particular be designed as a so-called "on-chip" guide formed on a substrate (for example, a silicon substrate). The optical guide has a core and optionally a cladding. The core is formed from a material that is optically transparent to the radiation, for example, a semiconductor material (e.g., silicon, a silicon nitride, or another silicon compound), glass, or plastic.The core has a higher refractive index than the surrounding material (for example, the cladding) and is used to guide the radiation within the guide. The axis of the optical guide does not have to be straight, but can also have one or more curved sections.

[0163] The term "propagating mode" as used here refers to the fact that, due to the design of the optical guide, only one or more solutions of the electromagnetic field equations exist that differ with regard to their electromagnetic field distribution and allow a propagating wave along the optical guide. Propagating modes can be different, particularly with regard to the electromagnetic field strength and / or relative phase position between electric and magnetic field components, in a plane perpendicular to the axis of the optical guide. The optical guide can have one or more propagating modes.The number of modes that can propagate in the optical fiber depends on the core dimensions and cross-sectional shape of the core, the refractive index difference between the core and the environment or cladding, and the individual mode profile (in particular the electromagnetic field strengths perpendicular to the axis of the optical fiber).

[0164] The term "evanescent field" as used herein refers to an electromagnetic field existing outside the core of the optical guide and decreasing with increasing distance from the surface of the core. Such an evanescent field is dependent on the propagating mode with respect to a spatial energy distribution. As will be described in more detail, the devices, systems, and methods disclosed herein utilize an evanescent field entering and thereby interacting with a wavelength reference to detect and at least partially compensate for a change in a spectral characteristic of a radiation source.

[0165] The term "radiation" as used herein refers to electromagnetic radiation in the visible and / or near-infrared and / or mid-infrared spectral range. The radiation source, if present, may be configured to emit radiation in the visible spectral range (for example in the range from 350 nm to 900 nm or in the range from 400 nm to 780 nm) and / or near-infrared spectral range (for example in the range from 800 nm to 2700 nm or in the range from 900 nm to 2700 nm or in the range from 900 nm to 2700 nm) and / or in the mid-infrared (MIR) spectral range (for example in the range from 1400 nm to 25 pm or in the range from 1400 nm to 10 pm or in the range from 1400 nm to 5 pm or in the range from up to 5 pm or up to 10 pm or up to 25 pm).

[0166] The term "optical measurement" as used herein refers to a measurement performed on a sample (e.g., a sample material and / or a sample body) using electromagnetic radiation in the visible and / or near-infrared spectral range and / or mid-infrared spectral range provided using the radiation source unit.

[0167] The term "reference measurement" as used here refers to a measurement carried out on a wavelength reference (in particular a solid-state standard) by means of which a change in a spectral characteristic of the radiation source(s) can be detected, in particular also quantified and measured.

[0168] The term "spectral characteristic" as used herein refers to at least one intensity or intensity distribution as a function of the emission wavelength of the radiation source(s).

[0169] The radiation source unit can be integrated into the photonic integrated circuit, i.e., in particular, it can also comprise optical components arranged on the substrate, such as one or more splitters and / or one or more combiners. The terms "splitter" and "combiner," as used here, refer to devices configured to divide optical radiation power guided in an optical conductor into multiple parts (splitter) or to feed optical radiation power guided in optical conductors to an optical conductor connected to the output of the combiner (combiner). The splitter and combiner can have identical configurations. In particular, the terms "splitter" and "combiner" should not be understood to necessarily require a different configuration.

[0170] The integrated photonic circuit can also comprise a multiplexer and / or demultiplexer. The multiplexer can be configured to perform a wavelength-dependent splitting of radiation received at a multiplexer input into different wavelength components, which can be coupled into different optical fibers connected to multiplexer outputs. Similarly, the demultiplexer can be configured to combine different wavelength components and provide them at a demultiplexer output.

[0171] The wavelength reference can be designed, in particular, as a solid-state standard. Compared to the use of a gas cell, this offers several advantages, particularly with regard to mechanical robustness, ease of manufacture, and stability with respect to environmental influences.

[0172] Figure 1 is a schematic representation of a radiation source unit 10. The radiation source unit 10 comprises a radiation source 12 arranged on a substrate 16. The radiation source unit 10 comprises a reference measuring device configured to perform a reference measurement with which a change in a spectral characteristic of the radiation source 12 can be detected. The change can, for example, comprise a change in the spectral characteristic as a function of time, temperature, and / or in comparison to a desired spectral characteristic.

[0173] The radiation source unit 10 comprises an integrated photonic circuit 11, which comprises the substrate 16 with the radiation source 12 arranged thereon, as well as a plurality of optical conductors 13. The optical conductors can be configured as optical fibers or in another manner familiar to those skilled in the art.

[0174] The reference measuring device has at least one wavelength reference 14. The at least one wavelength reference 14 is arranged on at least one optical conductor 13 of the photonic integrated circuit. The reference measuring device has a detector 15 integrated into the radiation source unit 10, which is configured to detect at least one optical measurement variable after radiation generated by the radiation source 12 has passed through the optical conductor 13 and interacted with the wavelength reference 14. The optical conductor 13 is configured such that an evanescent field of a propagating mode guided by the optical conductor 13 enters the wavelength reference 14 and can interact with the wavelength reference 14. In this way, based on the optical measurement variable detected by the detector 15, it can be determined whether a spectral characteristic of the radiation source 12 has changed.The wavelength reference 14 can have an absorption spectrum and / or reflection spectrum, which is schematically shown as detail S in Figure 1, and which is adapted to the desired spectral characteristic of the radiation source 12 and / or the application for which the radiation source unit 10 is used, in order to be able to detect relevant changes in the spectral characteristic of the radiation source 12.

[0175] The wavelength reference 14 is particularly advantageously designed as a solid-state standard, which can comprise a matrix made of a plastic material (e.g., PTFE). The solid-state standard can optionally comprise one or more dopants to achieve a desired absorption spectrum S and / or reflection spectrum that can be used to detect a change in the spectral characteristics of the radiation source 12. The wavelength reference 14 can be mounted as a solid on the optical conductor 13 of the integrated photonic circuit and / or applied by a printing process.

[0176] The integrated photonic circuit 11 with the wavelength reference 14 applied to the optical conductor 13 can be encapsulated with an encapsulation 17. In this way, the radiation source unit 10 can be provided as an integral, one-piece unit for use in an optical measuring system. The encapsulation 17 can be configured such that the radiation source unit 10 has a sample interface 18 for outputting radiation to be irradiated onto a sample (for example, a sample material and / or a sample body). The encapsulation 17 can be configured such that the radiation source unit 10 has an electrical interface 19 for outputting signals and / or data that indicate a change in the spectral characteristic of the radiation source 12 detected by the reference measuring device (and optionally also quantitatively measured).Such signals and / or data output via the electrical interface 19 can be used for computational compensation of the detected change in the spectral characteristics.

[0177] Figure 2 shows a schematic, partial sectional view of the radiation source unit 10. The photonic integrated circuit 11 has the optical guide 13 on the substrate 16. The substrate 16 can, for example, comprise a silicon substrate. The optical guide 13 can have a core 28 and a cladding 29. The cladding 29 has a refractive index and, at the mandrel region arranged between the core 28 and the wavelength reference 14, a cladding thickness such that an evanescent field of a propagating mode guided by the optical guide 13 enters the wavelength reference 14 and can interact with it.

[0178] The optical conductor 13 and in particular the core 28 of the optical conductor 13 can extend along an extension direction that is parallel to the substrate surface of the substrate 16. The wavelength reference 14 can also extend along at least a part of the optical conductor along this extension direction and thus parallel to the extension direction of the optical conductor.

[0179] 13. The wavelength reference 14 can also be flat, wherein the optical conductor 13 can have a curved (for example, spiral or meandering) geometry that extends in a plane parallel to the extension of the wavelength reference 14.

[0180] Other configurations are possible. In particular, the wavelength reference 14 can be arranged and the cladding 29 can be configured such that the wavelength reference 14 bears directly against the core 28. The cladding 29 can be configured to include the wavelength reference 14 as an integral component. In other words, the cladding 29 can include a solid-state standard (for example, a polymer-based solid-state standard into which dopants can optionally be introduced) or can be configured as a solid-state standard.

[0181] The radiation source unit 10 can also be designed such that along a part of the optical conductor the wavelength reference 14 is directly adjacent to the core 28 and that along a further part of the optical conductor a cladding different from the wavelength reference 14 is adjacent to the core 28.

[0182] The radiation source unit 10 can also be designed so that the wavelength reference

[0183] 14 is arranged within an outer envelope of the core 28.

[0184] The wavelength reference 14 may comprise a solid-state standard. The integration of a

[0185] Solid-state standards in the radiation source unit 10 offers various advantages. Compared to the integration of a gas cell, there are, among other things, process-related advantages. A solid-state standard can be applied to the photonic integrated circuit 11 using conventional techniques (so-called "pick and place" techniques). For a gas cell, a chamber suitable for the gas would first have to be manufactured and then filled with the corresponding gas. In addition, the pressure and temperature of the gas would have to be stabilized or controlled. Solids are established references in the form of white, gray, and wavelength standards, which are generally available with suitable certificates. A solid-state standard can represent a stable reference over a long period of time and independently of environmental influences. A solid-state standard allows for a variation of additives and mixing ratios (e.g.rare earths in a PTFE matrix), application-specific references adapted to the respective radiation source(s) 12 can be realized cost-effectively.

[0186] The wavelength reference 14 can be a polymer-based standard. This has the advantage that, unlike gas cells with narrow absorption bands, a wide spectral range is covered, and the individual peaks or spectral features are broad enough to be hit with narrowband laser lines, even without feedback or other stabilization.

[0187] The radiation source unit 10 can be configured such that at any time during operation a small portion of the laser power is diverted and the absorption of the wavelength reference 14 or the reflectance of the wavelength reference 14 is measured.

[0188] The wavelength reference 14 can be attached to the optical conductor of the photonic integrated circuit 11 in various ways. For example, the wavelength reference 14 can be printed. In an advantageous embodiment, the wavelength reference 14 can be attached to the optical conductor 13 of the photonic integrated circuit 11 by flip-chip mounting.

[0189] Various integration levels are conceivable. The wavelength reference 14 can be permanently connected to the photonic integrated circuit 11 during encapsulation. In a modular implementation, the wavelength reference 14 can be inserted interchangeably into the photonic integrated circuit 11.

[0190] While Figures 1 and 2 depict a single wavelength reference 14, the radiation source unit 10 may comprise multiple wavelength references, each of which can be measured during operation to detect and optionally quantify changes in the spectral characteristics of the radiation source 12. The use of multiple wavelength references, as described in more detail below, makes it possible to compensate for power fluctuations and wavelength fluctuations.

[0191] Figure 3 is a schematic representation of an optical measuring system 30 that

[0192] Radiation source unit 10 according to one embodiment. The optical measuring system 30 further comprises a detection device 31 with a sample light detector 32 and an evaluation device 33. The sample light detector 32 is configured to detect sample light 22 that emanates from the sample 20 upon irradiation by radiation 21 generated by the radiation source unit 10.

[0193] The evaluation device 33 can be configured to receive signals or data from the reference measuring device of the radiation source unit 10 via an electrical signal path 23, which can, for example, have a data bus, a plurality of signal lines, or another digital and / or analog data interface. The received signals or data can specify the change in the spectral characteristic of the radiation source 12 detected and optionally quantified by the reference measuring device of the radiation source unit 10. The evaluation device 13 can be configured to use the change in the spectral characteristic of the radiation source 12 detected by the reference measuring device of the radiation source unit 10 when evaluating the output signal of the sample light detector 32 in order to at least partially compensate for the change in the spectral characteristic of the radiation source 12.

[0194] The radiation source unit 10 and the detection device 31 can be installed in a common housing, as schematically indicated in Figure 3.

[0195] The radiation source unit 10 and / or the optical measuring system 30 may have at least one interface to enable measurement of the wavelength reference 14 by an optical system separate from the radiation source unit 10.

[0196] Figure 4 shows an embodiment of the radiation source unit 10 and the optical measuring system 30, in which the radiation source unit 10 can have a first optical interface 24 and a second optical interface 25. The optical interfaces 24, 25 can have a measuring window in the encapsulation 17 and / or fiber optic interfaces. The optical interfaces 24, 25 can have at least one interface 24 configured to guide radiation generated by the radiation source 12 out of the radiation source unit 10 and / or to introduce radiation from a source external to the radiation source unit 10 into the region of the optical conductor 13 where the wavelength reference 14 is arranged.The optical interfaces 24, 25 can have at least one further interface 25 configured to couple radiation out of the radiation source unit 10 after passing through the region of the optical conductor 13 where the wavelength reference 14 is arranged and / or to couple radiation in the direction of the detector 15. In this way, the wavelength reference 14, the radiation source 12, and / or the detector 15 can be spectrally measured, for example, by an external optical device. This data can be used, for example, for calibration purposes and / or for comparing multiple optical measuring systems. Figure 5 schematically shows an arrangement comprising the optical measuring system 30 and an additional optical system 40.The additional optical system 40 can have a source 41 that is configured to introduce radiation via the optical interface 24 into the region of the optical conductor 13 where the wavelength reference 14 is arranged, and / or to couple radiation in the direction of the detector 15 via the further optical interface. The additional optical system 40 can have a detection device 42 that is configured to receive radiation from the radiation source 12 coupled via the optical interface 24 and / or to receive radiation coupled via the further optical interface 25 after passing through the region of the optical conductor 13 where the wavelength reference 14 is arranged. The additional optical system 40 can thus be configured to spectrally measure the wavelength reference 14, the radiation source 12 and / or the detector 15. Results of the spectral measurement can be used by the evaluation device 33.

[0197] The radiation source unit 10 and / or the optical measuring system 30 can have various arrangements of multiple optical conductors, multiple wavelength references and, optionally, multiple (or even just one) detectors and / or optionally multiple radiation sources. Embodiments are described in more detail with reference to Figure 6, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11, Figure 12 and Figure 13. Even if not explicitly shown in these figures, the radiation source unit 10 each comprises a (only partially shown) photonic integrated circuit which can have the radiation source (or sources), the optical conductor(s), the detector(s) and optionally controllable elements such as controllable splitters and / or controllable couplers and / or multiplexers and / or demultiplexers.

[0198] Figure 6 schematically shows components of a radiation source unit 10. The radiation source unit 10 comprises an integrated photonic circuit with a radiation source 12 (for example, a laser source, in particular a multi-wavelength laser source) and a plurality of optical conductors. The radiation source unit 10 can be configured such that radiation generated by the radiation source 12 is split using splitters 50, 51, 52, 55. The splitters 50, 51, 52, 55 can comprise one or more controllably switchable splitters 51, 52, 55. After interaction with different wavelength references 14, 54, 57, the power of the individual paths can be combined via a combiner 58 and directed to a single detector 15.This is advantageous because a detector 15 is configured to detect the optical measurement variable after the interaction of the radiation generated by the radiation source 12 with different wavelength references 14, 54, 57. This detector 15 can simultaneously fulfill the function of the sample light detector 32 for the measurement on the sample 20. For example, the detector 15 can be designed as a large-area ex-InGas sensor, which does not necessarily have to be integrated into the integrated photonic circuit. Alternatively or in addition to the switchability of one or more splitters 51, 52, 55, the combiner 58 can also be controllably switchable.

[0199] The radiation source unit 10 can be configured such that, during operational operation in which radiation 21 is output for irradiating the sample 20, an intensity component is also supplied to one or more wavelength references 14, 54, 57 via a first splitter 50. The wavelength references 14, 54, 57 can optionally differ in terms of their absorption spectra and / or reflection spectra. Alternatively or additionally, the plurality of optical guides 13, 53, 56 on which the wavelength references 14, 54, 57 are arranged can differ in terms of their propagating modes. The splitter 50 can optionally be controllable, but does not necessarily have to be controllable. One or more of the splitters 51, 52, 55 can be controllable in order to supply radiation to the detector 15 in a controllable manner through the optical guides 13, 53, 56 or an optical guide 59.As mentioned, alternatively or additionally, the combiner 58 can be controllable.

[0200] The radiation source unit 10 has at least one controller 60 configured to control controllable components of the radiation source unit 10 for performing the reference measurement. The controller 60 can be configured to control one or more splitters, one or more combiners, one or more multiplexers, and / or one or more demultiplexers.

[0201] The radiation source unit 10 is configured such that the evanescent fields of the modes propagating in a plurality of optical guides 13, 53, 56 interact with the wavelength references 14, 54, 57 arranged along the respective optical guides 13, 53, 56. By using multiple wavelength references, each of which can be measured separately, changes in the spectral characteristics of the radiation source 12 can be more comprehensively detected and optionally quantified.

[0202] The radiation source 12 and the detector 15 can use the same material system and be implemented by the same chip. In particular, the detector 15 can be implemented by the chip that provides a gain material for the radiation source 12.

[0203] To implement detector 15 or multiple detectors for measuring the wavelength references, a material system is required that absorbs in the corresponding wavelength range. Since broadband detectors that cover the entire spectrum (e.g., ex-InGas) may be complex to implement, it may be advantageous to use the gain material of the radiation source(s) (e.g., GaAs, InP, or GaSb systems such as AlGaAs, InGaAsJnAs, InGaAs-JnAlGaAs, InGasP-on-InP, or GaInAsSb, or other material systems mentioned in US 2022 / 0200244 A1) for the detector 15 or detectors 15 as well. Figure 7 shows an embodiment of components of the radiation source unit 10, wherein the photonic integrated circuit comprises a chip 61 arranged on the substrate 16 with a material system that provides the gain material for the radiation source 12. The detector 15 uses this material system for detection.In this way, a change in the spectral characteristics of the radiation source 12 can be detected and optionally quantified in an efficient, robust and compact implementation.

[0204] The radiation source unit 10 can comprise multiple radiation sources. Since the individual detectors used for the reference measurement can be narrower-band than the overall spectrum composed of multiple radiation sources with multiple gain materials, it is advantageous to divert radiation for the reference measurement before combining the individual wavelengths provided by the different radiation sources and to perform the reference measurements for each radiation source individually, e.g., in parallel. A corresponding embodiment is shown in Figure 8.

[0205] Figure 8 shows components of the radiation source unit 10, wherein the photonic integrated circuit comprises a radiation source unit 12 and an additional radiation source unit 12'. Radiation generated by the radiation source unit 12 and the additional radiation source unit 12' can be guided to the sample interface 18 via splitters 50, 50' and optical conductors 62, 64 connected thereto via a multiplexer 65.

[0206] To detect changes in the spectral characteristics of the radiation source 12 and to also detect changes in the spectral characteristics of the additional radiation source 12', the reference measuring device has the wavelength references 14, 54, 57 and additional wavelength references 14', 54', 57', each of which can be configured as solid-state references. The portion of the radiation that is guided through the optical guides 13, 53, 56 or the additional optical guides 13', 53', 56' and thereby interacts with the various wavelength references is branched off by the splitters 50, 50' before the radiation generated by the radiation source 12 and the additional radiation source 12' can be combined by the multiplexer 65.

[0207] The functionality of the reference measuring device can be implemented in the same way for each of the radiation sources 12, 12'. In particular, the components that perform the reference measurement for detecting a change in the spectral characteristics of the additional radiation source 12' can be implemented as described with reference to Figure 7. The corresponding components are each identified by an apostrophe next to the corresponding reference symbol.

[0208] Depending on the detected change in the spectral characteristics of the radiation source

[0209] 12 and the detected change in the spectral characteristic of the additional radiation source 12', the change can be at least partially compensated, for example by computational correction and / or stabilization of the corresponding radiation source 12, 12'.

[0210] While Figures 6, 7, and 8 depict embodiments in which a single detector is configured to perform the detection required for the reference measurement per radiation source, several different detectors can also be used. Figure 9 shows an exemplary embodiment.

[0211] Figure 9 shows a partial representation of a radiation source unit 10 which, in addition to the detector 15, has further detectors 76, 77 in order to measure further wavelength references 54, 57 and thus to detect changes in the spectral characteristics of the radiation source 12.

[0212] The radiation source unit 10 has a plurality of couplers 70, 71, 72, 73, at least some of which can optionally be controllable. However, such controllability of the couplers is not necessarily required, since separate detectors are provided for different optical conductors.

[0213] The radiation source unit 10 is configured such that the radiation source 12 emits radiation at at least one wavelength into an optical guide. A large portion of the power is guided via the coupler 70 through an optical guide 62 to the sample interface 18. A portion of the power of the radiation generated by the radiation source 12 is guided to the detectors 15, 76, 77 via optical guides 13, 53, 56, each of which has a wavelength reference arranged thereon. Due to the interaction of the evanescent field of the mode propagating in the optical guides 13, 53, 56 with the respective wavelength reference 14, 54, 57, an absorption and / or reflectance of the respective wavelength reference can be measured, and a change in the spectral characteristics of the radiation source 12 can be detected.

[0214] The coupler 70 is advantageously configured such that a large portion of the power of the radiation generated by the radiation source 12 (for example, at least 90% or at least 99%) can be coupled out via the sample interface 18. The remainder is available for reference measurements by the reference measuring device integrated on the substrate 16.

[0215] The couplers 70, 71, 72, 73 can comprise, for example, a directional coupler, a multi-mode interference coupler, and / or a Mach-Zehnder interferometer. The couplers can have a fixed or adjustable splitting ratio.

[0216] For the reference measurement, the radiant power is further divided so that one path is available for each wavelength reference 14, 54, 57. The wavelength references 14, 54, 57 can be standards, e.g., a diffuse reflection standard and / or a wavelength standard.

[0217] The radiation source unit 10 can have an optical conductor 59 without a wavelength reference arranged thereon. The radiation source unit 10 can be configured to perform a white balance depending on a signal detected from the optical conductor 59. Alternatively or additionally, the radiation source unit 10 can have a detector 78 that does not receive any light in order to perform a dark balance.

[0218] To enable interaction between a mode propagating in the optical guide and the wavelength reference arranged on the optical guide with the greatest possible propagation constraints, the optical guide 13 can have a curved section. A radius of curvature of a central axis of the optical guide 13 (for example, a central axis of the core 28) can be directed parallel to a substrate surface of the substrate 16 on which the optical guide 13 is arranged.

[0219] Figure 10 shows an exemplary embodiment of the optical conductor 13 in a plan view, viewed perpendicular to the substrate surface of the substrate 16, on which the optical conductor 13 is arranged. The optical conductor has a spiral section 81 and / or meandering section. The wavelength reference 14 can be applied flatly over the spiral section 81 and / or meandering section. In this way, a more precise detection of changes in the spectral characteristics of the radiation source 12 or multiple radiation sources of the radiation source unit 10 is enabled by increasing the length over which the propagating mode of the optical conductor 13 can interact with the wavelength reference 14 via its evanescent field, compared to a straight optical conductor.

[0220] An embodiment as described with reference to Figure 10 can be used in any of the radiation source units 10 disclosed herein.

[0221] Figure 11 shows an embodiment of the radiation source unit 10, which has a plurality of planar wavelength references 14, 54 arranged on a curved section 81, 82 of an optical conductor 13, 53 assigned to the wavelength reference.

[0222] The radiation source unit 10 comprises a radiation source 12 and an additional radiation source 12'. The radiation generated by the radiation source 12 and the additional radiation generated by the additional radiation source 12' are fed to a splitter 50 via a multiplexer 91. The splitter 50 directs a large portion of the radiation power (for example, at least 90%, at least 95%, or at least 99%) to the sample interface 18 for output to the sample 20. Via a further splitter 51, which can be controllable, the combined radiation is selectively fed to various optical guides 13, 53, 59, with an associated wavelength reference 14, 54 being arranged on at least two of the optical guides. For detection, the optical guides 13, 53, 59 can be coupled to a combiner 58.From the combiner 58, the radiation that has interacted with the associated wavelength reference 14, 54 for the radiation paths along the optical conductors 13, 53 is fed to at least one detector. Figure 11 shows, by way of example, an embodiment with a detector 15, which is implemented by a gain material of a chip 61 of the radiation source 12, and with an additional detector 15', which is implemented by a gain material of an additional chip 63 of the additional radiation source 12'. The chips 61, 63 are arranged on the substrate 16. The detector 15 and the additional detector 15' are coupled to the combiner 58 via a demultiplexer 92.

[0223] The radiation source unit 10 according to each of the embodiments disclosed here can have one or more additional optical interfaces in addition to the sample interface 18. The one or more additional optical interfaces can be configured to enable measurement of the wavelength reference 14 by an optical system external to the radiation source unit 10.

[0224] Figure 12 shows a partially exploded view of the radiation source unit 10, in which the encapsulation 17 has at least one measuring window 101, 102 to enable interaction of an external optical system with at least one wavelength reference 14, 54. This allows, for example, the absorption and / or reflectance of the at least one wavelength reference 14, 54 to be measured. Alternatively or additionally, the at least one wavelength reference 14, 54 can be used to calibrate the external optical system and is thus not limited to acting as a reference for detecting a change in a spectral characteristic of at least one radiation source of the radiation source unit 10.

[0225] Figure 13 shows a radiation source unit 10 in which the further optical interface has one or more fiber couplers 116, 117. The at least one fiber coupler 116, 117 can be configured to enable coupling of external radiation into at least one optical conductor 13, 53, 59 of the radiation source unit 10. The at least one fiber coupler 116, 117 can alternatively or additionally be configured to enable coupling out of radiation after passing through at least one optical conductor 13, 53, 59 (and in particular after interaction of the evanescent field of the propagating mode with the wavelength reference 14, 54).

[0226] The radiation source unit 10 can have an optical conductor 118 connected to the fiber coupler 116 and the splitter 111 for selectively coupling external radiation into one of the plurality of optical conductors 13, 53, 59. The radiation source unit 116 can have a plurality of splitters 113, 114, 115 and optical conductors 119 connecting them to the further fiber coupler 116 to enable coupling out of radiation after passing through at least one optical conductor 13, 53, 59 (and in particular after interaction of the evanescent field of the propagating mode with the wavelength reference 14, 54).

[0227] In each of the radiation source units explained with reference to Figures 1 to 13

[0228] 10, the optical conductors can be formed as part of the photonic integrated circuit on the substrate 16. Regardless of whether the further optical interfaces are implemented as measurement windows and / or using fiber coupling points, the further optical interfaces provide access to the initial and / or repeated alignment with a

[0229] Reference measurement system.

[0230] The radiation source unit 10 and / or the optical measuring system 30 can be configured for various measuring applications, for example, for performing an interferometric measurement, for performing a spectral analytical measurement, for performing a measurement on biological sample material, for performing a measurement on medical sample material, for performing a measurement on a sample body and / or for performing a measurement in an industrial manufacturing and / or quality assurance system.

[0231] Figure 14 is a schematic representation of a system 120 comprising the optical measuring system with the radiation source unit 10, the sample light detector 32, and the evaluation device 33. The system 120 can be configured such that the evaluation device 33 executes a control function depending on an output signal or output data of the sample light detector 32. The control function can include controlling a human-machine interface 121, transferring data to a controller 122 for one or more actuators 123, and / or controlling a storage system.

[0232] Figure 15 is a schematic representation of the system 120 in which the controller 122 is configured to control at least one component of a manufacturing system, for example a robot 124, which may be configured as a multi-axis robot.

[0233] Figure 16 is a flowchart of a method 130. The method 130 may be performed using the radiation source unit 10 or the optical measurement system 30 according to one embodiment.

[0234] At 131, a sample (for example, sample material and / or a sample body) is illuminated using a radiation source unit 10 according to one embodiment with radiation generated by the radiation source unit 10. Depending on a change in a spectral characteristic of the radiation source detected by the reference measuring device of the radiation source unit 10, the radiation source can be controlled or regulated such that stabilization occurs and / or the change is reduced compared to a desired spectral characteristic.

[0235] At 132, sample light 22 emanating from the sample is detected and evaluated. The detection and evaluation can be performed using an interferometer and / or spectrometer, but are not limited thereto. The evaluation can be performed using a change in a spectral characteristic of the radiation source detected by the reference measuring device of the radiation source unit 10. In particular, the change in the spectral characteristic of the radiation source can be at least partially computationally compensated during the evaluation.

[0236] At 133, a control action dependent on the evaluation can optionally be performed. The control action can include controlling a human-machine interface, a storage system, or at least one actuator.

[0237] Figure 17 is a flowchart of a method 140. The method 140 may be performed to manufacture the radiation source unit 10. The method 140 may be performed automatically by a manufacturing facility.

[0238] At 141, a photonic integrated circuit is provided for mounting one or more wavelength references. The photonic integrated circuit comprises at least one radiation source and at least one optical guide. The radiation source and the at least one optical guide are mounted on a substrate of the photonic integrated circuit, which may be, for example, a silicon substrate.

[0239] At 142, one or more wavelength references are arranged on the at least one optical conductor of the photonic integrated circuit. This may involve flip-chip assembly. Alternatively or additionally, at least one of the wavelength references may be printed, for example, using inkjet printing techniques.

[0240] While embodiments have been described with reference to the figures, modifications may be implemented in further embodiments. For example, the following modifications may be used alternatively or cumulatively:

[0241] - The wavelength reference is advantageously a solid-state wavelength reference (in particular, a solid-state standard), but is not limited to this. For example, the wavelength reference may comprise an aqueous solution, a liquid in a chamber and / or in a microfluidic system, or a gel.

[0242] - The radiation source unit can be designed as an on-chip unit, in which the radiation source(s), the detector(s), the optical guide(s), the wavelength reference(s), and optionally additional optical and / or electronic components are arranged on the same substrate. These components can be encapsulated together, although this is not mandatory.

[0243] - While radiation source units with one, two, three or more than three wavelength references have been described by way of example, the radiation source unit may have a different number of wavelength references.

[0244] - Various techniques by which the optical measurement variable acquired for the reference measurement (e.g., a reference spectrum) can be used to control the radiation source and / or to computationally compensate for a change in the spectral characteristics of the radiation source are familiar to those skilled in the art. Examples of these techniques are described in EP 3 332 230 B1 and / or US 2023 / 0112044 A1. These and other techniques known to those skilled in the art for using the result of the reference measurement can be used by the radiation source unit, the optical measuring system, and / or methods according to exemplary embodiments.

[0245] - The optical guide and the wavelength reference arranged thereon can be designed such that, due to the interaction of the evanescent field with the wavelength reference, absorption occurs, which is detected and used by the reference measuring device. Alternatively or additionally, a reflectance of the wavelength reference can also be measured and used to detect and quantify a change in the spectral characteristics of the radiation source.

[0246] - The radiation source unit may comprise, in addition to the optical conductor 13, 53, 56 on which a wavelength reference is arranged, at least one optical conductor 62, 64 for providing radiation for performing an optical measurement.

[0247] - The radiation source unit 10 can be configured so that a reflection of the wavelength reference is used as an injection for the radiation source. This can be particularly helpful for so-called "injection locking" of the radiation source.

[0248] - The wavelength reference can be integrated into or on the radiation source 12. This can be particularly advantageous for spectrally shaping the gain.

[0249] While embodiments have been described that can be used in industrial manufacturing or quality control systems or in medical technology, the disclosed techniques can also be used in other areas of application.

[0250] The present disclosure also encompasses embodiments with any combination of features mentioned or shown for different embodiments. It also encompasses individual features in the figures, even if they are shown there in connection with other features and / or are not mentioned above or below. Furthermore, the alternative embodiments described in the figures and the description and individual alternative features thereof may be excluded from the subject matter of the invention or from the disclosed subject matter.

[0251] The terms "comprise" and "comprise" and derivatives thereof indicate a non-exhaustive relationship and do not exclude the presence of other elements or steps. The indefinite article "a" or "an" and derivatives thereof do not exclude the presence of a plurality of the corresponding elements. The functions of several features listed in the claims can be fulfilled by one unit or one step, respectively. A machine-readable instruction code that can be executed by a programmable circuit to carry out methods according to embodiments can be stored and / or distributed on a suitable medium, such as an optical storage medium or a solid-state medium provided together with or as part of other hardware. The instruction code can also be distributed in other forms, such as a modulated data signal sequence.

[0252] Embodiments of the invention provide improved techniques for performing optical measurements.

Claims

CLAIMS 1. A radiation source unit (10) for performing an optical measurement, comprising: a radiation source (12; 12, 12'), an optical guide (13) for guiding radiation generated by the radiation source (12; 12, 12'), wherein the optical guide (13) is configured to guide a propagating mode, a substrate (16) on which the radiation source (12; 12, 12') and the optical guide (13) are arranged, and a reference measuring device (14, 15; 14, 15, 50, 51, 52, 55, 54, 57, 58, 60; 14, 15, 70-73, 54, 57, 76-79) for performing a reference measurement, with which a change in a spectral characteristic of the radiation source (12; 12, 12'), wherein the reference measuring device (14, 15; 14, 15, 50, 51, 52, 55, 54, 57, 58, 60; 14, 15, 70-73, 54, 57, 76-79) comprises a wavelength reference (14; 14, 54; 14, 54, 57;14, 14', 54, 54', 57, 57') arranged along at least a portion of the optical guide (13) such that an evanescent field of the propagating mode enters the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57'); 2. Radiation source unit (10) according to claim 1, wherein the optical conductor (13) has a core (28) and a cladding (29), and wherein the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') is arranged adjacent to the core (28) or to the cladding (29) or the cladding (29) has the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') or the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') within a outer envelope of the core (28).

3. Radiation source unit (10) according to claim 1 or claim 2, wherein the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') comprises a solid-state wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57').

4. Radiation source unit (10) according to one of the preceding claims, wherein the reference measuring device (14, 15; 14, 15, 50, 51, 52, 55, 54, 57, 58, 60; 14, 15, 70-73, 54, 57, 76-79) has at least one detector (15; 15, 15'; 15, 76-79) which is arranged on the substrate (16), wherein the at least one detector (15; 15, 15'; 15, 76-79) is coupled to the optical conductor (13) and is configured to detect an optical measurement variable after interaction of the radiation generated by the radiation source (12; 12, 12') with the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57').

5. Radiation source unit (10) according to claim 4, wherein the radiation source unit (10) is configured to control or regulate the radiation source (12; 12, 12') as a function of the optical measurement variable in order to change the spectral characteristic and / or to provide output data dependent on the optical measurement variable for a computational compensation of the spectral characteristic of the radiation source (12; 12, 12').

6. Radiation source unit (10) according to claim 4 or claim 5, comprising a chip (61; 61, 63) comprising a gain material of the radiation source (12; 12, 12'), wherein the detector (15, 15') comprises at least a portion of the gain material of the radiation source (12; 12, 12').

7. Radiation source unit (10) according to one of the preceding claims, comprising at least one further optical guide (53; 53, 56), wherein each further optical guide (53; 53, 56) of the at least one further optical guide (53; 53, 56) is arranged to guide at least one further propagating mode, and at least one further wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') which is arranged such that an evanescent field of the at least one further propagating mode enters the at least one further wavelength reference (54; 54, 57), wherein the further wavelength reference (54; 54, 57) has different optical properties from the wavelength reference (14).

8. Radiation source unit (10) according to claim 7, further comprising a combiner (58; 58, 58') coupled to the optical conductor (13) and the at least one further optical conductor (53; 53, 56) and configured to supply the mode propagating through the optical conductor (13) or the further mode propagating through the further optical conductor (53; 53, 56) to a detection device, and / or a splitter (51) configured to couple the radiation into at least one of the optical conductor (13) and the further optical conductor (53; 53, 56), and a controller (60) for controlling the combiner (58; 58, 58') and / or the splitter (51).

9. Radiation source unit (10) according to one of the preceding claims, wherein the optical guide (13) has at least one curved section (81) in which an axis of the optical guide (13) has a curvature, wherein the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') is arranged on the at least one curved section (81).

10. The radiation source unit (10) according to claim 9, wherein the at least one curved section (81) forms a two-dimensional spiral and / or meandering geometry extending parallel to a substrate (16) plane, wherein the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') covers the two-dimensional spiral and / or meandering geometry in a planar manner.

11. Radiation source unit (10) according to one of the preceding claims, wherein a photonic integrated circuit (11) comprises the substrate (16), the radiation source (12; 12, 12') and the optical guide (13), wherein the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') is arranged via a flip-chip assembly on the optical guide (13) of the photonic integrated circuit (11), wherein the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') is encapsulated together with the photonic integrated circuit (11) or is detachably connected to the photonic integrated circuit (11) in a non-destructive manner.

12. Radiation source unit (10) according to one of the preceding claims, further comprising an encapsulation (17), wherein the encapsulation (17) has an optical interface (24, 25; 101, 102; 116, 117) for optically measuring the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57').

13. Optical measuring system (30), comprising: the radiation source unit (10) according to one of the preceding claims, wherein the radiation source unit (10) has a sample interface for irradiating radiation generated by the radiation source (12; 12, 12') onto a sample (20), a sample light detector (31) for detecting light received from the sample (20) Sample light (22) and at least one evaluation device (33) for evaluating output signals or Output data of the sample light detector (31).

14. A method for producing a radiation source unit (10) comprising an integrated photonic circuit (11), wherein the integrated photonic circuit comprises a radiation source (12; 12, 12'), an optical guide (13) for guiding radiation generated by the radiation source (12; 12, 12'), and a substrate (16) on which the radiation source (12; 12, 12') and the optical guide (13) are arranged, wherein the optical guide (13) is configured to guide a propagating mode, the method comprising: Arranging a wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') on the optical guide (13) of the integrated photonic circuit, wherein the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') is arranged along at least a portion of the optical guide (13) such that an evanescent field of the propagating mode enters the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57').

15. The method of claim 14, wherein the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') comprises a solid-state wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57'), and wherein arranging the wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57') comprises flip-chip mounting of the solid-state wavelength reference (14; 14, 54; 14, 54, 57; 14, 14', 54, 54', 57, 57').

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