Optical components, optical signal monitoring modules, and optical modules

Abstract

This invention relates to the field of optical communication technology and provides an optical component, an optical signal monitoring module, and an optical module. The optical component includes a polarization bandpass filter, a non-reciprocal polarization reflector located on a first side of the polarization bandpass filter, and a bandpass polarization reflector located on a second side of the polarization bandpass filter; the second side of the polarization bandpass filter is adjacent to the first side of the polarization bandpass filter. The polarization bandpass filter is used to transmit a first optical signal with a first polarization state transmitted by the non-reciprocal polarization reflector, and also to transmit an OTDR signal with a first polarization state fed back from a single-fiber bidirectional transmission fiber, and to reflect an OTDR signal with a second polarization state fed back from a single-fiber bidirectional transmission fiber, as well as all OSC signals; the wavelength of the OSC signal is different from the wavelength of the OTDR signal. The optical component, optical signal monitoring module, and optical module provided by this invention are small in size and low in cost.

Description

Technical Field

[0001] This invention belongs to the field of optical communication technology, and particularly relates to an optical component, an optical signal monitoring module, and an optical module. Background Technology

[0002] The operation and maintenance of fiber optic networks is inseparable from the monitoring of the physical status of the fiber optic network. Optical time-domain reflectometer (OTDR) and optical supervisory channel (OSC) are two main monitoring methods. Specifically, OTDR is a technique that measures Fresnel backscattering and Rayleigh scattering in optical fibers to obtain information on fiber uniformity, defects, breaks, splice coupling, and other properties. It can be used to measure fiber attenuation, splice loss, locate fiber fault points, and understand the loss distribution along the fiber length. An optical supervisory channel refers to inserting a monitoring wavelength (monitoring channel) generated by the node at the transmitting end of the fiber optic signal transmission system and separating the monitoring wavelength at the receiving end of the transmission system to test and monitor the fiber optic connection status and performance of the fiber optic transmission system.

[0003] Performing bidirectional optical time-domain reflectometry (OTDR) and optical monitoring channels on a single fiber is the simplest and most effective way to monitor the physical state of an optical fiber network. Furthermore, network operators desire to integrate a single-fiber bidirectional OTDR+OSC system into a single SFP (Small Form-factor Pluggable) optical module, which necessitates the use of an integrated, small-volume optical component.

[0004] However, current single-fiber bidirectional OTDR+OSC systems, such as Figure 1 As shown, there are two OTDR+OSC systems A and B at each end of the single-fiber bidirectional transmission fiber 101. Each system contains a signal transmitting laser, LD-A-λ1 and LD-B-λ2, which transmit optical signals with wavelengths of λ1 and λ2, respectively. When the wavelength transmitted locally reaches the other party, it becomes an OSC signal, and when it is reflected by the single-fiber bidirectional transmission fiber 101, it becomes an OTDR signal.

[0005] Therefore, each single-fiber bidirectional OTDR+OSC system must receive two wavelengths of signals, one is the OSC signal from the other end, and the other is the OTDR signal reflected by the single-fiber bidirectional transmission fiber 101. After the two signals enter the single-fiber bidirectional OTDR+OSC system, the OTDR / OSC signals need to be separated by using a three-port optical fiber WDM (Wavelength Division Multiplexing) device 102 first, and then the same wavelength of the transmitted signal and the reflected signal are separated by using another three-port optical circulator 103. The separated signals are received by the OTDR-A-λ1 photodetector (PD) and the OSC-A-λ2 photodetector at the A end, and by the OSC-B-λ1 photodetector and the OTDR-B-λ2 photodetector at the B end.

[0006] As can be seen, the existing scheme uses discrete optical fiber devices (optical fiber WDM device and optical circulator), which are large in size and high in cost, and cannot meet the requirement of integrating optical components into SFP optical modules. SUMMARY

[0007] The purpose of the present application is to provide an optical component, an optical signal monitoring module and an optical module, aiming to solve the technical problem of large size of the optical component for optical signal monitoring in the prior art.

[0008] The present application is implemented in the following manner. In a first aspect, an optical component is provided, comprising a polarization band-pass filter, a non-reciprocal polarization reflector located at a first side of the polarization band-pass filter, and a band-pass polarization reflector located at a second side of the polarization band-pass filter; the second side of the polarization band-pass filter is an adjacent side of the first side of the polarization band-pass filter;

[0009] The non-reciprocal polarization reflector is configured to transmit a first optical signal and convert a polarization state of the first optical signal into a first polarization state, and to reflect an OTDR signal having the first polarization state and convert a polarization state of the OTDR signal from the first polarization state to a second polarization state; the OTDR signal is the first optical signal having the first polarization state reflected by a single-fiber bidirectional transmission fiber, and has the first polarization state and the second polarization state.

[0010] The polarization band-pass filter is configured to transmit the first optical signal having the first polarization state conducted by the non-reciprocal polarization reflector, and to transmit the OTDR signal having the first polarization state fed back by the single-fiber bidirectional transmission fiber, reflect the OTDR signal having the second polarization state fed back by the single-fiber bidirectional transmission fiber, and reflect all OSC signals; the OSC signals have a wavelength different from that of the OTDR signals.

[0011] The band-pass polarization reflector is configured to reflect the OTDR signal having the second polarization state reflected by the polarization band-pass filter and transmit the OSC signal reflected by the polarization band-pass filter.

[0012] In an optional embodiment, the non-reciprocal polarization reflector comprises a sub-wavelength grating polarization reflector and a 45-degree Faraday rotator arranged in sequence along the propagation direction of the first optical signal.

[0013] The sub-wavelength grating polarization reflector is configured to transmit an optical signal having a polarization direction identical to the period direction of the metal grating lines and reflect an optical signal having a polarization direction perpendicular to the period direction of the metal grating lines, and the 45-degree Faraday rotator is configured to rotate the polarization direction of the optical signal by 45 degrees.

[0014] In an optional embodiment, the sub-wavelength grating polarization reflector is formed on a corresponding light transmission surface of the 45-degree Faraday rotator.

[0015] In an optional embodiment, the non-reciprocal polarization reflector comprises a polarization beam splitter and a 45-degree Faraday rotator arranged in sequence along the propagation direction of the first optical signal, and a mirror located on one side of the polarization beam splitter.

[0016] The 45-degree Faraday rotator is configured to rotate the polarization direction of the optical signal by 45 degrees, the mirror is configured to reflect the optical signal reflected by the polarization beam splitter, and the polarization beam splitter is configured to transmit the first optical signal and reflect the OTDR signal conducted by the 45-degree Faraday rotator.

[0017] In an optional embodiment, the mirror is formed on a corresponding light transmission surface of the polarization beam splitter.

[0018] In an optional embodiment, the polarization band-pass filter is a multilayer dielectric film type polarization band-pass filter.

[0019] In an optional embodiment, the band-pass polarization reflector comprises a polarization rotator arranged close to the polarization band-pass filter and a band-pass mirror arranged away from the polarization band-pass filter.

[0020] The polarization rotator is configured to rotate the polarization direction of linearly polarized light after two reflections by 90 degrees, and the band-pass mirror is configured to reflect the OTDR signal and transmit the OSC signal.

[0021] In an optional embodiment, the polarization rotator is a 1 / 4 wave plate or a 45-degree Faraday rotator.

[0022] In an alternative embodiment, the bandpass mirror is implemented by depositing a multilayer dielectric film on the light-emitting surface of the polarization rotator.

[0023] In an optional embodiment, the optical component further includes a lens module located on the third side of the polarization bandpass filter, the lens module being used to expand the beam of the OTDR signal and the OSC signal input to the optical component from the outside; the third side of the polarization bandpass filter is the opposite side of the first side of the polarization bandpass filter.

[0024] Secondly, an optical signal monitoring module is provided, including optical components, an optical signal transmitting unit, an input / output terminal, a first optical signal receiving unit, and a second optical signal receiving unit;

[0025] Wherein, the optical component is the optical component provided in the above embodiments; the optical signal emitting unit is located on the first side of the non-reciprocal polarization reflector and is used to emit a first optical signal; the first side of the non-reciprocal polarization reflector is the side corresponding to the first side of the polarization bandpass filter; the input / output terminal is located on the third side of the polarization bandpass filter and is used to input and output optical signals; the third side of the polarization bandpass filter is the side opposite to the first side of the polarization bandpass filter; the first optical signal receiving unit is located on the fourth side of the optical component and is used to receive and process the OTDR signal transmitted by the optical component; the second optical signal receiving unit is located on the second side of the optical component and is used to receive and process the OSC signal transmitted by the optical component; the second side of the optical component corresponds to the second side of the polarization bandpass filter, and the fourth side of the optical component is the side opposite to the second side of the optical component.

[0026] Thirdly, an optical module is provided, including a housing and the optical signal monitoring module provided in the above embodiments installed in the housing.

[0027] The first aspect of the present invention has the following technical advantages over the prior art: The optical component provided by the embodiments of the present invention can separate OTDR signals and OSC signals in different wavelength ranges, and can also separate the transmitted signal (the first optical signal mentioned above) and the received signal (OTDR signal) in the same wavelength range. This can realize the combined function of fiber WDM devices and optical circulators in the prior art, effectively reduce the size of the optical component, and the cost of the required components is lower than that of optical components in the prior art, which can meet the requirements for integration into SFP optical modules.

[0028] It is understood that the beneficial effects of the second and third aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure and optical path of an existing optical signal monitoring system;

[0031] Figure 2 This is a schematic diagram of the structure and optical path of an optical signal monitoring module provided in an embodiment of the present invention;

[0032] Figure 3a This is a schematic diagram of the reflection characteristics of a polarization bandpass filter used in an embodiment of the present invention;

[0033] Figure 3b This is a schematic diagram of the reflection characteristics of a polarization bandpass filter used in another embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure and optical path of a non-reciprocal polarization reflector used in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the structure and optical path of a non-reciprocal polarization reflector used in another embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of the structure and optical path of the bandpass polarizing reflector used in the embodiments of the present invention;

[0037] Figure 7 This is a schematic diagram of the reflection characteristics of the bandpass mirror used in the embodiments of the present invention;

[0038] Figure 8 This is a schematic diagram of the structure and optical path of an optical signal monitoring module provided in another embodiment of the present invention.

[0039] Explanation of reference numerals in the attached figures:

[0040] 101. Single-fiber bidirectional transmission optical fiber; 102. Fiber optic WDM device; 103. Optical circulator; 110. Polarization bandpass filter; 120. Non-reciprocal polarization reflector; 121. Subwavelength grating polarization reflector; 122. 45-degree Faraday rotator; 123. Polarization beam splitter; 124. Mirror; 130. Bandpass polarization reflector; 131. Polarization rotator; 132. Bandpass mirror; 140. Lens module; 200. Optical signal transmitting unit; 300. Input / output terminal; 400. First optical signal receiving unit; 500. Second optical signal receiving unit. Detailed Implementation

[0041] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0042] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0046] To address the problems existing in the prior art, this invention provides an optical component that can realize the functions of fiber optic WDM devices and optical circulators in the prior art. When applied to an optical signal monitoring module, it enables the optical signal monitoring module to integrate OTDR and OSC functions, and is small in size and low in cost, allowing the optical signal monitoring module to be packaged into an SFP optical module.

[0047] Specifically, to implement OTDR and OSC functions, two optical signal monitoring modules are generally required, which are connected via a single-fiber bidirectional transmission fiber. One optical signal monitoring module sends an optical signal with wavelength λ1 into the single-fiber bidirectional transmission fiber, while the other sends an optical signal with wavelength λ2. The module sending the λ1 signal then receives the first OTDR signal reflected from the single-fiber bidirectional transmission fiber, as well as the first OSC signal transmitted through the fiber. Similarly, the module sending the λ2 signal receives the second OTDR signal reflected from the single-fiber bidirectional transmission fiber, as well as the second OSC signal transmitted through the fiber.

[0048] The first OTDR signal is an OTDR signal formed by reflection of an optical signal with wavelength λ1 through a single-fiber bidirectional transmission fiber; the second OTDR signal is an OTDR signal formed by reflection of an optical signal with wavelength λ2 through a single-fiber bidirectional transmission fiber; the first OSC signal is an OSC signal formed by transmission of an optical signal with wavelength λ2 through a single-fiber bidirectional transmission fiber; and the second OSC signal is an OSC signal formed by transmission of an optical signal with wavelength λ1 through a single-fiber bidirectional transmission fiber.

[0049] It should be noted that each of the above optical signals generally has a certain wavelength range, that is, λ1 and λ2 are both range values.

[0050] For details, please refer to Figure 2 As shown, the optical signal monitoring module includes optical components, an optical signal transmitting unit 200, an input / output terminal 300, a first optical signal receiving unit 400, and a second optical signal receiving unit 500. The optical signal transmitting unit 200 emits a first optical signal. The input / output terminal 300 inputs and outputs optical signals. The first optical signal receiving unit 400 receives and processes the OTDR signal transmitted through the optical components. The second optical signal receiving unit 500 receives and processes the OSC signal transmitted through the optical components. The optical components used are those provided in this embodiment of the invention.

[0051] The optical component provided in this embodiment of the invention includes a polarization bandpass filter 110, a non-reciprocal polarization reflector 120 located on a first side of the polarization bandpass filter 110, and a bandpass polarization reflector 130 located on a second side of the polarization bandpass filter 110. Specifically, the polarization bandpass filter 110 generally has multiple sides, i.e., it has multiple sides, and the second side of the polarization bandpass filter 110 is the adjacent side of the first side of the polarization bandpass filter 110.

[0052] The non-reciprocal polarization reflector 120 is used to transmit a first optical signal and convert the polarization state of the first optical signal to a second polarization state. It is also used to reflect an OTDR signal with a first polarization state and convert the polarization state of the OTDR signal from the first polarization state to a second polarization state. The OTDR signal is formed by reflecting the first optical signal with a first polarization state through a single-fiber bidirectional transmission fiber 101, and thus has both a first and a second polarization state. It should be noted that the first and second polarization states in this paper are generally two polarization states with mutually perpendicular polarization directions. For example, one polarization state corresponds to P-polarized light, and the other polarization state corresponds to S-polarized light. For ease of description, the following explanation uses the example of P-polarized light corresponding to the first polarization state and S-polarized light corresponding to the second polarization state. It should be understood that when the light corresponding to the first polarization state is S-polarized light and the light corresponding to the second polarization state is P-polarized light, the principle is the same as when the light corresponding to the first polarization state is P-polarized light and the light corresponding to the second polarization state is S-polarized light; only the polarization directions of the corresponding optical signals are different.

[0053] The polarization bandpass filter 110 is used to transmit the first optical signal with a first polarization state transmitted by the non-reciprocal polarization reflector 120, and also to transmit the OTDR signal with a first polarization state fed back by the single-fiber bidirectional transmission fiber 101, reflect the OTDR signal with a second polarization state fed back by the single-fiber bidirectional transmission fiber 101, and all OSC signals. Specifically, the aforementioned OSC signals also have a first polarization state and a second polarization state. The term "all OSC signals" here includes both OSC signals with the first polarization state and OSC signals with the second polarization state. The wavelength of the OSC signal is different from the wavelength of the OTDR signal.

[0054] It should be noted that the first optical signal, OTDR signal, and OSC signal in this embodiment are all optical signals with a certain wavelength range. The difference between the wavelength of the OSC signal and the wavelength of the OTDR signal means that their wavelength ranges do not overlap.

[0055] The bandpass polarization reflector 130 is used to reflect the OTDR signal with a second polarization state reflected by the polarization bandpass filter 110 and to transmit the OSC signal reflected by the polarization bandpass filter 110.

[0056] The working principle of the optical signal monitoring module using the optical components provided in this embodiment of the invention is as follows. For ease of description and understanding, the OTDR and OSC functions are described separately.

[0057] OTDR function:

[0058] The optical signal transmitting unit 200 emits a first optical signal. The wavelength passband of this first optical signal is λ1, and it contains only a single polarization component, denoted as λ. 1OThen the first optical signal λ 1O A polarization signal with a first polarization state (denoted as λ) is formed by transmission through the non-reciprocal polarization reflector 120. 1p ), then the polarization signal λ 1p The signal is transmitted through the polarization bandpass filter 110, then propagates through the input / output terminal 300 to the single-fiber bidirectional transmission fiber 101, and is then reflected by the single-fiber bidirectional transmission fiber 101 to form the OTDR signal. Due to the polarization effect of the fiber, the OTDR signal reflected back from the single-fiber bidirectional transmission fiber 101 has two mutually perpendicular polarization components, denoted as λ. 1s 'and λ 1p '. Then the OTDR signal λ with the first polarization state 1p 'Able to follow the above polarization signal λ 1p The propagation path returns, passing sequentially through input / output terminal 300 and polarization bandpass filter 110 to non-reciprocal polarization reflector 120, where it is reflected to form an OTDR signal λ with a second polarization state. 1s ', then the signal λ 1s After being reflected by the polarization bandpass filter 110, it is finally received by the first optical signal receiving unit 400.

[0059] At the same time, the portion of the OTDR signal fed back from the transmission fiber that has a second polarization state, namely λ 1s The signal first enters the optical signal monitoring module through the input / output terminal 300, then is reflected by the polarization bandpass filter 110 to the bandpass polarization reflector 130, and then reflected by the bandpass polarization reflector 130 to form an OTDR signal λ with the first polarization state. 1p The signal is then transmitted through the polarization bandpass filter 110 and finally received by the first optical signal receiving unit 400.

[0060] After receiving the two types of OTDR signals, the first optical signal receiving unit 400 processes them to generate corresponding electrical signals and analyzes them to obtain corresponding detection parameters, or generates corresponding electrical signals and sends them to an external signal processing device for processing to obtain corresponding detection parameters.

[0061] OSC Functions:

[0062] The second optical signal (wavelength passband λ2) emitted by another optical signal monitoring module is transmitted through the single-fiber bidirectional transmission fiber 101 to generate a corresponding OSC signal. This OSC signal also contains two polarization components, S and P, denoted as λ. 2s and λ 2pRegardless of the polarization state, the OSC signal first enters the optical signal monitoring module in the OTDR function through the input / output terminal 300, then is reflected by the polarization bandpass filter 110 and propagated to the bandpass polarization reflector 130, and then transmitted through the bandpass polarization reflector 130 to the second optical signal receiving unit 500, where it is received.

[0063] Therefore, the optical component provided by the embodiments of the present invention can separate OTDR signals and OSC signals in different wavelength ranges, and can also separate the transmitted signal (the first optical signal mentioned above) and the received signal (OTDR signal) in the same wavelength range. This can realize the combined function of fiber WDM devices and optical circulators in the prior art, effectively reduce the size of the optical component, and the cost of the required components is lower than that of optical components in the prior art, which can meet the requirements for integration into SFP optical modules.

[0064] The non-reciprocal polarization reflector 120 described above can be configured in various ways. For ease of understanding, examples are given below.

[0065] In an optional embodiment, such as Figure 4 As shown, the non-reciprocal polarization reflector 120 includes a subwavelength grating polarization reflector 121 and a 45-degree Faraday rotator 122 arranged sequentially along the propagation direction of the first optical signal.

[0066] Among them, the subwavelength grating polarizing reflector 121 is used to transmit light signals with the same polarization direction as its own metal grating period direction and to reflect light signals with the polarization direction perpendicular to its own metal grating period direction. The 45-degree Faraday rotator 122 is used to rotate the polarization direction of the light signal by 45 degrees.

[0067] Specifically, the subwavelength grating polarization reflector 121 has broadband polarization reflection performance. It generally has multiple metal grating lines arranged periodically along a certain direction. It can transmit polarized light with a polarization direction consistent with the periodic direction of the metal grating lines, while reflecting polarized light with a polarization direction perpendicular to the periodic direction of the metal grating lines. The periodic direction of the metal grating lines mentioned here refers to the arrangement direction of the metal grating lines, which is generally perpendicular to the extension direction of the metal grating lines. Figure 4 In the configuration shown, the initial polarization direction of the first optical signal emitted by the optical signal emitting unit 200 is consistent with the periodic direction of the metal grid line, and at this time, the polarization direction of the first optical signal and the periodic direction of the metal grid line are both at a 45-degree angle to the polarization direction corresponding to the first polarization state.

[0068] In use, the first optical signal first passes through the subwavelength grating polarization reflector 121, at which point the polarization direction of the first optical signal remains unchanged. Then, the first optical signal passes through the 45-degree Faraday rotator 122 and rotates by 45 degrees, adjusting its polarization direction to the first polarization state. The OTDR signal with this first polarization state is denoted as λ.1p '.

[0069] When the OTDR signal with the first polarization state propagates from the side where the polarization bandpass filter 110 is located to the non-reciprocal polarization reflector 120, it first passes through the 45-degree Faraday rotator 122 and is rotated by 45 degrees. This makes its polarization direction perpendicular to the periodic direction of the metal grating lines in the subwavelength grating polarization reflector 121, thus causing it to be reflected by the metal grating lines. It then propagates again towards the 45-degree Faraday rotator 122, and is rotated by 45 degrees again, adjusting to the second polarization state. The OTDR signal with the second polarization state at this time is denoted as λ. 1s '.

[0070] It should be noted that, Figure 4 λ 1p 'and λ 1s The separation of the positions is only for the convenience of drawing illustrations; the actual positions are the same.

[0071] The non-reciprocal polarization reflector 120 adopts the structure provided in this embodiment, which is simple in structure, easy to obtain materials and assemble, and has a low cost.

[0072] The aforementioned subwavelength grating polarizing reflector 121 can be one of three types of gratings: subwavelength dielectric, subwavelength metal, or a hybrid of subwavelength dielectric and metal. Alternatively, it can be formed directly on one of these three types of gratings using microfabrication techniques on a light-transmitting surface of the 45-degree Faraday rotator 122. When the subwavelength grating polarizing reflector 121 is set independently of the 45-degree Faraday rotator 122, it facilitates material sourcing and assembly. When the subwavelength grating polarizing reflector 121 is directly formed on the corresponding light-transmitting surface of the 45-degree Faraday rotator 122 using microfabrication techniques, the non-reciprocal polarizing reflector 120 can be made smaller.

[0073] In another alternative embodiment, such as Figure 5 As shown, the non-reciprocal polarization reflector 120 includes a polarization beam splitter 123 and a 45-degree Faraday rotator 122 arranged sequentially along the propagation direction of the first optical signal, and a reflector 124 located on one side of the polarization beam splitter 123.

[0074] The 45-degree Faraday rotator 122 is used to rotate the polarization direction of the optical signal by 45 degrees. The reflector 124 is used to reflect the optical signal reflected by the polarization beamsplitter 123. The polarization beamsplitter 123 transmits the first optical signal and reflects the OTDR signal transmitted by the 45-degree Faraday rotator 122. Specifically, the polarization direction of the OTDR signal transmitted by the 45-degree Faraday rotator 122 forms a 45-degree angle with the polarization direction of the OTDR signal having the first polarization state.

[0075] When the first optical signal is emitted, it first passes through the polarization beam splitter 123, at which point the polarization direction of the first optical signal remains unchanged. Then, the first optical signal passes through the 45-degree Faraday rotator 122 and rotates by 45 degrees, adjusting its polarization direction to the first polarization state. This first optical signal with the first polarization state is denoted as λ. 1p .

[0076] When receiving an OTDR signal, the OTDR signal with the first polarization state (denoted as λ) 1p When the signal propagates from the side of the polarization bandpass filter 110 to the non-reciprocal polarization reflector 120, it first passes through the 45-degree Faraday rotator 122, where it is rotated by 45 degrees, thus changing its polarization direction and no longer being in the first polarization state. Therefore, it is reflected back to the direction of the reflector 124 when it passes through the polarization beam splitter 123. After receiving the signal, the reflector 124 reflects it back to the polarization beam splitter 123. During this process, the polarization direction of the signal does not change, so when the signal touches the polarization beam splitter 123 again, it is reflected again and propagates back to the direction of the 45-degree Faraday rotator 122. After being rotated by 45 degrees by the 45-degree Faraday rotator 122 again, it is adjusted to the second polarization state. The OTDR signal with the second polarization state at this time is denoted as λ. 1s '.

[0077] Similarly, Figure 5 λ 1p 'and λ 1s The separation of the positions is only for the convenience of drawing illustrations; the actual positions are the same.

[0078] The non-reciprocal polarization reflector 120 adopts the structure provided in this embodiment, which is simple in structure, easy to obtain materials and assemble, and has a low cost.

[0079] The aforementioned reflector 124 can be a common plane reflector, or it can be formed on the corresponding light-transmitting surface of the polarization beamsplitter 123. Specifically, when the reflector 124 is formed on the corresponding light-transmitting surface of the polarization beamsplitter 123, it can be formed by depositing a high-reflectivity metal film or a high-reflectivity multilayer dielectric film on the corresponding light-transmitting surface of the polarization beamsplitter 123, or by attaching a reflective layer to the corresponding light-transmitting surface of the polarization beamsplitter 123, or by attaching the reflector 124 to the corresponding light-transmitting surface of the polarization beamsplitter 123. Forming the reflector 124 on the corresponding light-transmitting surface of the polarization beamsplitter 123 allows for a smaller size of the non-reciprocal polarization reflector 120.

[0080] Of course, in other embodiments, the non-reciprocal polarization reflector can also adopt other structures, such as adding a half-wave plate to adjust the polarization direction so that the geometric configuration of the polarization beam splitter 123 is consistent with the polarization bandpass filter 110, which facilitates assembly, and other variations, as long as the above functions can be achieved.

[0081] In an optional embodiment, such as Figure 2 As shown, the polarization bandpass filter 110 is a multilayer dielectric thin-film type polarization bandpass filter. Specifically, the polarization bandpass filter 110 has a filter layer formed of multiple dielectric thin films. This filter layer allows a first optical signal with a first polarization state to pass through, while allowing optical signals of other wavelength ranges and / or polarization states to be reflected, that is, it only allows the aforementioned λ... 1p and λ 1p 'Transmission, and λ 1s , λ 1s '、λ 2s and λ 2p Universal reflection, its reflection characteristics are as follows Figure 3a As shown; or, as Figure 3b As shown, the filter layer allows light signals with a first polarization state and a wavelength range within a preset range to be transmitted, and allows light signals with other wavelength ranges and / or polarization states to be reflected. The preset range is greater than or equal to the wavelength range corresponding to the first light signal.

[0082] Figure 3a and Figure 3b The dashed line represents the reflection spectrum of S-light, and the solid line represents the reflection spectrum of P-light. These two figures show that the reflectivity of P-light is close to zero within the λ1 passband, meaning it can be transmitted; the reflectivity of P-light is close to 100% within the λ2 passband; and the reflectivity of S-light is close to 100% within both the λ1 and λ2 passbands. Performance outside the λ1 and λ2 passbands is not considered.

[0083] In addition, the polarization bandpass filter 110 is generally used under conditions of large-angle incident and reflection, that is, the above-mentioned filter layer is generally set at an angle of 45 degrees. Of course, other angles can also be used, such as 30 degrees, 60 degrees, etc., as long as they can meet the requirements of its use.

[0084] The polarization bandpass filter 110 adopts the structure provided in this embodiment, which is simple and easy to manufacture.

[0085] In addition to the aforementioned filter layer, the polarizing bandpass filter 110 may also include other light guide components, such as two triangular prisms that can be joined to form a quadrangular prism. In this case, the filter layer can be formed between the two triangular prisms. This helps in the shaping of the filter layer and protects it. Of course, in other embodiments, only one prism may be provided, with the filter layer deposited on one of the light-transmitting surfaces of the prism. This is not a limitation; any implementation that achieves the above-mentioned functions is acceptable.

[0086] In an optional embodiment, such as Figure 6As shown, the bandpass polarizing reflector 130 includes a polarization rotator 131 disposed near the polarization bandpass filter 110 and a bandpass mirror 132 disposed away from the polarization bandpass filter 110. The polarization rotator 131 is used to rotate the polarization direction of linearly polarized light by 90 degrees after it passes through twice, and the bandpass mirror 132 is used to reflect the OTDR signal and transmit the OSC signal.

[0087] Specifically, the bandpass polarizing reflector 130 is used under the condition of small-angle incident, transmission, or reflection, approximately 0 degrees of incident angle. Of course, other incident angles can also be used, as long as the above functions are achieved. The bandpass reflector 132 has the following characteristics: Figure 7 As shown in the reflection characteristics, since the bandpass polarizing reflector 130 is used under the condition of small-angle incident light, the S-ray and P-ray have approximately the same reflection spectrum, exhibiting total reflection for the λ1 passband and total transmission for the λ2 passband. Therefore, the λ2 passband ray will pass through the bandpass polarizing reflector 130, becoming a λ2 passband ray that retains both polarization states.

[0088] In use, the OTDR signal with the second polarization state is reflected by the polarization bandpass filter 110 and propagated to the polarization rotator 131. After transmission, it is reflected by the bandpass mirror 132 and passes through the polarization rotator 131 again. The polarization direction of the OTDR signal is rotated by 90 degrees after passing through the polarization rotator 131 twice, and its polarization state is changed from the second polarization state to the first polarization state. Then the OTDR signal passes through the polarization bandpass filter and is received by the first optical signal receiving unit.

[0089] Meanwhile, the OSC signal can be reflected by the polarization bandpass filter and propagated to the bandpass polarization reflector 130, and then pass through the polarization rotator 131 and the bandpass reflector 132 in sequence, and be received by the second optical signal receiving unit.

[0090] The bandpass polarizing reflector 130 adopts the structure provided in this embodiment, which is simple and easy to assemble.

[0091] The aforementioned polarization rotator can be a quarter-wave plate, a 45-degree Faraday rotator, or any other structure capable of achieving the above functions. When a quarter-wave plate is used, the polarization rotator is inexpensive and compact. When a 45-degree Faraday rotator is used, the optical axis direction does not need to be considered, which facilitates assembly.

[0092] The aforementioned bandpass reflector can be a standalone bandpass reflector, or it can be achieved by depositing a multilayer dielectric film on the light-emitting surface of the polarization rotator. When the bandpass reflector is fabricated using a coating method, the bandpass polarization reflector is smaller in size.

[0093] In an optional embodiment, such as Figure 8As shown, the optical assembly also includes a lens module 140 located between the polarization bandpass filter 110 and the input / output terminal 300, i.e., the lens module 140 is located on the third side of the polarization bandpass filter 110. The third side of the polarization bandpass filter 110 is the opposite side to the first side of the polarization bandpass filter 110, and is also the side of the polarization bandpass filter 110 closer to the input / output terminal 300.

[0094] Lens module 140 is used to expand the beam of OTDR and OSC signals input from external sources to the optical components. In this embodiment, lens module 140 may include one or more lenses. The lenses may be one of aspherical lenses, Clens, GrinLens, or GIF (Gradient Index Fiber).

[0095] Since the polarization bandpass filter 110 is incident at a large angle, and the center spacing between the OTDR signal and the OSC signal is small, and the beam divergence angle input from the input / output terminal 300 is large, Figure 3a and Figure 3b The reflected spectrum characteristics shown are also difficult to achieve. Therefore, when the passband center spacing between the OTDR signal and the OSC signal is small (e.g., less than 40 nm), the solution provided in this embodiment can be used to expand the input OTDR signal and OSC signal and reduce the divergence angle.

[0096] Please refer to Figure 2 As shown, in another embodiment of the present invention, an optical signal monitoring module is provided, including optical components, an optical signal transmitting unit 200, an input / output terminal 300, a first optical signal receiving unit 400, and a second optical signal receiving unit 500.

[0097] The optical components described in the embodiments above are the same as those provided. The optical signal transmitting unit 200 is located on the first side of the non-reciprocal polarization reflector 120 and is used to emit a first optical signal. The first side of the non-reciprocal polarization reflector 120 is the side corresponding to the first side of the polarization bandpass filter 110, and is also the side away from the polarization bandpass filter 110. The input / output terminal 300 is located on the third side of the polarization bandpass filter 110 and is used to input and output optical signals. The third side of the polarization bandpass filter 110 is the side opposite to the first side of the polarization bandpass filter 110. The first optical signal receiving unit 400 is located on the fourth side of the optical component and is used to receive and process the OTDR signal transmitted by the optical component. The second optical signal receiving unit 500 is located on the second side of the optical component and is used to receive and process the OSC signal transmitted by the optical component. The second side of the optical component corresponds to the second side of the polarization bandpass filter 110, and the fourth side of the optical component is the side opposite to the second side of the optical component.

[0098] Specifically, in this embodiment, the optical signal transmitting unit 200 can be one or more laser transmitters. The input / output terminal 300 is generally an optical fiber, used to transmit the optical signal output by the optical signal monitoring module to the transmission optical fiber, and also used to receive the OSC signal transmitted by the transmission optical fiber and the reflected OTDR signal. The structures of the first optical signal receiving unit 400 and the second optical signal receiving unit 500 can be the same or different. They can each include a detector, or they can each include a detector and a signal processing device electrically connected to the detector. The specific choice can be flexibly made according to the application needs, and no unique limitation is made here.

[0099] The working principle of the optical signal monitoring module provided in this embodiment of the invention is as follows:

[0100] Transmission: The λ1O emitted by the optical signal transmitting unit 200, after passing through the non-reciprocal polarization reflector 120, has its polarization state rotated by 45 degrees to become λ. 1p The signal is further transmitted through the polarization bandpass filter 110 to the input / output terminal 300, and then output to the peripheral transmission fiber through the input / output terminal 300.

[0101] Received OTDR signal: λ1' is the wavelength of the OTDR signal reflected back from the transmission fiber, which is the same as the wavelength of λ1O, and contains λ 1p 'and λ 1s The two components are input to the polarization bandpass filter 110 via input / output terminal 300, according to... Figure 4 The reflection spectrum shown, λ 1s 'Reflected, λ 1p 'Transmitted;'

[0102] λ 1s Upon reaching the bandpass polarizer 130, the polarization state is reflected and simultaneously rotated by 90 degrees, becoming λ. 1p The light returns and is transmitted through the polarization bandpass filter 110, reaching the first optical signal receiving unit 400 where it is received.

[0103] λ 1p After passing through the polarization bandpass filter 110, the light reaches the non-reciprocal polarization reflector 120. Upon reflection, the polarization state rotates by 90 degrees, becoming λ. 1s The light returns and is reflected by the polarization bandpass filter 110, reaching the first optical signal receiving unit 400 where it is received.

[0104] It is evident that the first optical signal receiving unit 400 received the two polarization state signals of the OTDR, which is complete.

[0105] Received OSC signal: λ2 is the far-end transmission wavelength transmitted through the optical fiber, containing λ 2p and λ 2sThe two components are input to the polarization bandpass filter 110 via the input / output terminal 300, according to... Figure 3a and Figure 3b The reflection spectrum shown, λ 2s and λ 2p All particles are reflected when passing through the polarization bandpass filter 110, and after reaching the bandpass polarization reflector 130, according to... Figure 7 The characteristics shown indicate that all signals can be transmitted and finally reach the second optical signal receiving unit 500. The first optical signal receiving unit 400 receives both polarization states of the OSC signal, which is also complete.

[0106] The optical signal monitoring module provided in this embodiment of the invention uses the optical components provided in the above embodiments, integrating OTDR and OSC functions into one unit, making it small in size, low in cost, and easy to assemble into an SFP optical module.

[0107] In another embodiment of the present invention, an optical module is provided, including a housing and an optical signal monitoring module provided in the above embodiment installed in the housing.

[0108] The optical module in this embodiment can be an SFP optical module or other optical modules that can accommodate the aforementioned optical signal monitoring module. The optical module provided in this embodiment uses the optical signal monitoring module described in the previous embodiment, enabling OTDR+OSC functionality and contributing to its miniaturization and low-cost design.

[0109] The above description is merely a preferred embodiment of the present invention and only specifically describes the technical principles of the present invention. These descriptions are only for explaining the principles of the present invention and should not be construed as limiting the scope of protection of the present invention in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention, as well as other specific embodiments of the present invention that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of the present invention.

Claims

1. An optical assembly comprising: The polarization band-pass filter, a non-reciprocal polarization reflector on a first side of the polarization band-pass filter, and a band-pass polarization reflector on a second side of the polarization band-pass filter; the second side of the polarization band-pass filter is an adjacent side of the first side of the polarization band-pass filter; The non-reciprocal polarization reflector is configured to transmit a first optical signal and convert a polarization state of the first optical signal into a first polarization state, and configured to reflect an OTDR signal having the first polarization state and convert a polarization state of the OTDR signal from the first polarization state to a second polarization state; the OTDR signal is the first optical signal having the first polarization state reflected by a single-fiber bidirectional transmission optical fiber, and has the first polarization state and the second polarization state; The polarization band-pass filter is configured to transmit the first optical signal having the first polarization state conducted by the non-reciprocal polarization reflector, transmit the OTDR signal having the first polarization state fed back by the single-fiber bidirectional transmission optical fiber, and reflect the OTDR signal having the second polarization state and all OSC signals fed back by the single-fiber bidirectional transmission optical fiber; the OSC signal has a wavelength different from that of the OTDR signal; The band-pass polarization reflector is configured to reflect the OTDR signal having the second polarization state reflected by the polarization band-pass filter, and transmit the OSC signal reflected by the polarization band-pass filter; The band-pass polarization reflector comprises a polarization rotator arranged close to the polarization band-pass filter and a band-pass mirror arranged away from the polarization band-pass filter; The polarization rotator is configured to rotate a polarization direction of linearly polarized light by 90 degrees after passing through twice, and the band-pass mirror is configured to reflect the OTDR signal and transmit the OSC signal, the OSC signal is transmitted to the band-pass polarization reflector after being reflected by the polarization band-pass filter, and then sequentially passes through the polarization rotator and the band-pass mirror and is received by a second optical signal receiving unit.

2. The optical assembly of claim 1, wherein, The non-reciprocal polarization reflector comprises a sub-wavelength grating polarization reflector and a 45-degree Faraday rotator arranged in sequence along a propagation direction of the first optical signal; The sub-wavelength grating polarization reflector is configured to transmit an optical signal having a polarization direction same as a period direction of a metal grating line of the sub-wavelength grating polarization reflector, and reflect an optical signal having a polarization direction perpendicular to the period direction of the metal grating line, and the 45-degree Faraday rotator is configured to rotate a polarization direction of an optical signal by 45 degrees.

3. The optical assembly of claim 2, wherein, The sub-wavelength grating polarization reflector is formed on a corresponding light transmission surface of the 45-degree Faraday rotator.

4. The optical assembly of claim 1, wherein, The non-reciprocal polarization reflector comprises a polarization beam splitter and a 45-degree Faraday rotator arranged in sequence along a propagation direction of the first optical signal, and a mirror arranged on one side of the polarization beam splitter; The 45-degree Faraday rotator is configured to rotate a polarization direction of an optical signal by 45 degrees, the mirror is configured to reflect an optical signal reflected by the polarization beam splitter, and the polarization beam splitter is configured to transmit the first optical signal and reflect the OTDR signal conducted by the 45-degree Faraday rotator.

5. The optical assembly of claim 4, wherein, The mirror is formed on a corresponding light passing surface of the polarization beam splitter.

6. The optical assembly of claim 1, wherein, The polarization band-pass filter is a multi-layer dielectric thin film type polarization band-pass filter.

7. The optical assembly of claim 1, wherein, The polarization rotator is a 1 / 4 wave plate or a 45 degree Faraday rotator.

8. The optical assembly of claim 1, wherein, The band-pass mirror is realized by coating a multi-layer dielectric film on the light output surface of the polarization rotator.

9. The optical assembly of any of claims 1-8, wherein, The optical assembly further comprises a lens module located at the third side of the polarization band-pass filter, the lens module being used for expanding the OTDR signal and the OSC signal inputted into the optical assembly from outside; the third side of the polarization band-pass filter is the opposite side of the first side of the polarization band-pass filter.

10. An optical signal monitoring module, characterized by The optical assembly, the optical signal transmitting unit, the input / output terminal, the first optical signal receiving unit and the second optical signal receiving unit are comprised. The optical assembly is the optical assembly of any one of claims 1-9; the optical signal transmitting unit is located at the first side of the non-reciprocal polarization reflector and is used for transmitting the first optical signal; the first side of the non-reciprocal polarization reflector is a side corresponding to the first side of the polarization band-pass filter; the input / output terminal is located at the third side of the polarization band-pass filter and is used for inputting and outputting optical signals; the third side of the polarization band-pass filter is the opposite side of the first side of the polarization band-pass filter; the first optical signal receiving unit is located at the fourth side of the optical assembly and is used for receiving and processing the OTDR signal conducted by the optical assembly; the second optical signal receiving unit is located at the second side of the optical assembly and is used for receiving and processing the OSC signal conducted by the optical assembly; the second side of the optical assembly corresponds to the second side of the polarization band-pass filter, and the fourth side of the optical assembly is a side arranged opposite to the second side of the optical assembly.

11. An optical module characterized by comprising: The optical signal monitoring module is mounted in the shell.

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