Optical receiver and method for manufacturing the same

Abstract

An object of the present disclosure is to broaden the bandwidth of an optical receiver with a simple configuration. [Solution] The optical receiver 100 disclosed herein comprises a subcarrier 2, a PD 3 provided on the subcarrier 2, which receives light and is driven by a voltage supply from an external bias power supply E, and a dielectric layer 5 formed within the subcarrier 2.

Description

[Technical Field]

[0001] The present disclosure relates to an optical receiver. [Background technology]

[0002] In conventional optical receivers, a PD (photodetector) is driven by a bias voltage supplied from a TIA (transimpedance amplifier) ​​(see Non-Patent Document 1). On the other hand, when driving an APD (avalanche photodiode), the bias voltage from the TIA alone is insufficient, so a separate external bias power supply is required.

[0003] Conventionally, such external bias power supplies are provided outside the subcarrier where the PD and TIA are provided, and are connected to the subcarrier via metal wires and bypass capacitors for noise reduction, supplying voltage to the PD.

[0004] Generally, the bandwidth of an optical receiver is determined by the impedance between the bypass capacitor and the PD. In conventional optical receivers, there is a lower limit to the length of the metal wire connecting the bypass capacitor and the subcarrier, so it is not possible to sufficiently shorten the distance between the bypass capacitor and the subcarrier where the PD is installed, making it difficult to realize a wideband optical receiver. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Li et al., “100 Gbit / s co-designed optical receiver with hybrid integration”, Opt. Express. Vol. 29, no. 10, 14304, 2021. Summary of the Invention [Problem to be solved by the invention]

[0006] In order to solve the above-mentioned problems, an object of the present disclosure is to provide a technique that can widen the bandwidth of an optical receiver with a simple configuration. [Means for solving the problem]

[0007] To achieve the above object, the optical receiver of the present disclosure employs a technique in which a dielectric is formed within a subcarrier on which a light receiving element is provided.

[0008] Specifically, the optical receiver of the present disclosure comprises: A subcarrier and a light receiving element provided on the subcarrier, which receives light and is driven by a voltage supplied from an external power source; a dielectric formed within the subcarrier.

[0009] The dielectric may be formed in a GND via of the subcarrier.

[0010] Further, a high frequency line is formed on the subcarrier, the light receiving element is in contact with one surface of the high-frequency line, The dielectric may be in contact with the other surface of the high-frequency line.

[0011] Further, a high frequency line is formed on the subcarrier, the light receiving element is in contact with one surface of the high-frequency line, The dielectric may be formed on a surface of the subcarrier opposite to a surface on which the high-frequency line is provided.

[0012] The dielectric may also be a chip capacitor.

[0013] The subcarrier may be provided with a TIA (Transimpedance Amplifier) ​​that supplies a voltage to the light receiving element.

[0014] Specifically, the method for manufacturing an optical receiver according to the present disclosure includes the steps of: A method for manufacturing an optical receiver having a subcarrier, a light receiving element provided in the subcarrier and driven by a voltage supplied from an external power source, and a dielectric formed within the subcarrier, the method comprising: The dielectric is formed in the subcarrier by crystal growth.

[0015] The above disclosures can be combined as much as possible. [Effects of the Invention]

[0016] According to the present disclosure, the bandwidth of an optical receiver can be broadened with a simple configuration. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram illustrating a configuration of an optical receiver according to a first embodiment of the present disclosure. [Figure 2] 4 is a graph illustrating the effects of the optical receiver according to the first embodiment in comparison with related optical receivers. [Figure 3] 3A to 3C are diagrams illustrating a manufacturing process of the optical receiver according to the first embodiment. [Figure 4] 5A to 5C are diagrams illustrating a manufacturing process of an optical receiver according to a modified example of the first embodiment. [Figure 5] FIG. 2 is a diagram illustrating a configuration of an optical receiver according to a modified example of the first embodiment. [Figure 6] FIG. 10 is a diagram illustrating a configuration of an optical receiver according to a second embodiment of the present disclosure. [Figure 7] FIG. 10 is a diagram illustrating a configuration of an optical receiver according to a third embodiment of the present disclosure. [Figure 8] FIG. 1 is a diagram illustrating the configuration of a related optical receiver. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings indicate the same components.

[0019] (First embodiment) [Configuration of the optical receiver according to the first embodiment] An optical receiver 100 according to a first embodiment of the present disclosure will be described with reference to Fig. 1 to Fig. 5. Fig. 1 is a diagram illustrating the configuration of the optical receiver 100 according to the first embodiment. The optical receiver 100 mainly includes a carrier 1, a subcarrier 2, a PD (Photodetector) 3, a TIA (Transimpedance Amplifier) ​​4, and a dielectric layer 5. The dielectric layer 5 is an example of a "dielectric" in the present disclosure.

[0020] Specifically, the optical receiver 100 includes: Subcarrier 2 and a PD3 provided on the subcarrier 2, which receives light and is driven by a voltage supplied from an external bias power supply E; a dielectric layer 5 formed within the subcarrier 2.

[0021] The carrier 1 is made of a metal with sufficiently high conductivity to function as a GND plane. For example, the carrier 1 is made of Kovar plated with Au. The carrier 1 is formed to be sufficiently larger than the subcarrier 2. The subcarrier 2 is disposed on the carrier 1.

[0022] In this embodiment, the subcarrier 2 has dimensions of 3.0×5.0×0.15 (length×width×thickness) mm 3The size of the subcarrier 2 (combination of length, width, and thickness) is not limited to the above, and can be any size depending on the components arranged on the subcarrier 2. However, in order to perform high-frequency operation, it is preferable that the thickness of the subcarrier 2 is 0.15 mm or less. Furthermore, by making the thickness of the subcarrier 2 0.15 mm or less, it is possible to suppress deviations in the electromagnetic field mode. This makes it possible to obtain desired frequency characteristics.

[0023] A GND via 2a is formed on the left side of the subcarrier 2. The GND via 2a is formed by filling it with copper. A dielectric layer 5 is provided on top of the GND via 2a. The subcarrier 2 is made of a material capable of forming the GND via 2a, such as AlN (when InP is used for the PD 3), Si, or quartz. The subcarrier 2 may be either multi-layer or single-layer.

[0024] High-frequency lines 21, 22, and 23 are formed on the subcarrier 2. The high-frequency line 21 is in contact with the lower surface of the left portion of the PD3. The upper surface of the high-frequency line 21 is an example of "one surface of a high-frequency line" in this disclosure. The high-frequency line 22 is in contact with the lower surface of the right portion of the PD3 and the lower surface of the left portion of the TIA4. The high-frequency line 23 is in contact with the lower surface of the right portion of the TIA4. Each high-frequency line has a back-side GND plane. Each high-frequency line is, for example, a coplanar line with a GND plane or a microstrip line. The subcarrier 2 functions as a dielectric layer for each high-frequency line. In this embodiment, the length of the high-frequency line 22 between the PD3 and the TIA4 is 0.2 mm. However, the length of each high-frequency line is not limited to this and may be any length depending on the size and arrangement of each component.

[0025] In this embodiment, PD3 has dimensions of 0.3×0.4×0.15 (length×width×thickness) mm 3 The PD3 is a light-receiving element of about the same size. The PD3 is made of, for example, InP. However, the size and material of the PD3 are not limited to these and can be any size depending on the application and situation. The direction of light incidence on the PD3 is arbitrary, and light may be incident from above, below, or the side.

[0026] The PD 3 is driven by a bias voltage supplied from the TIA 4 via a high-frequency line 22. A bias voltage is also supplied to the PD 3 from an external bias power supply E via a high-frequency line 21 and a wire L.

[0027] In this embodiment, the TIA 4 has dimensions of 2.0×3.0×0.15 (length×width×thickness) mm 3 The TIA 4 is made of, for example, SiGe. However, the size and material of the TIA 4 are not limited to this and can be determined as desired depending on the application and circumstances.

[0028] In this embodiment, the dielectric layer 5 is formed in a flat plate shape, and has dimensions of 0.1×0.1×0.0003 (length×width×thickness) mm 3 The plane size of the dielectric layer 5 is about 0.1 × 0.1 mm 2 The thickness is not limited to this range, and any planar size larger than this may be used. 0.0003 mm is the lower limit of the thickness of the dielectric layer 5, and the thickness of the dielectric layer 5 may be thicker. However, it is preferable that the thickness of the dielectric layer 5 does not exceed 150 μm (0.15 mm).

[0029] The dielectric layer 5 is made of, for example, SiO2 or the like. However, the material of the dielectric layer 5 is not limited to this. Specifically, the volume and material (dielectric constant) of the dielectric layer 5 are determined according to the frequency (noise) to be cut. In other words, the volume and material (dielectric constant) are determined so as to ensure the required capacitance according to the frequency to be cut. For example, if the required capacitance according to the frequency to be cut is 10 pF, the volume and material are determined so as to ensure 10 pF.

[0030] The dielectric layer 5 needs to have a withstand voltage three to four times the drive voltage of the PD 3. For example, if the drive voltage of the PD 3 is 25V, the withstand voltage of the dielectric layer 5 needs to be designed to be about 100V.

[0031] [Dielectric layer placement] In this embodiment, the dielectric layer 5 is provided above the GND via 2a of the subcarrier 2. In other words, the dielectric layer 5 is embedded in the subcarrier 2 directly below the PD3. The bottom surface of the dielectric layer 5 contacts the top surface of the GND via 2a of the subcarrier 2, and the top surface of the dielectric layer 5 contacts the bottom surface of the high-frequency line 21. The bottom surface of the high-frequency line 21 is an example of the "other surface of the high-frequency line" in this disclosure. In particular, in this embodiment, both surfaces are in contact over the entire area. This allows the dielectric layer 5 to function as a bypass capacitor. In other words, it provides the PD3 or the subcarrier 2 with a bypass capacitor function. Furthermore, because the dielectric layer 5 and the high-frequency line 21 are in direct contact, the inductance between the dielectric layer 5 and the PD3 / high-frequency line 21 can be made negligibly small. Therefore, the bandwidth can be controlled simply by adjusting the impedance between the PD3 and the TIA 4.

[0032] [effect] Next, the effects of the optical receiver 100 will be described with reference to the graph in Fig. 2, in comparison with a related optical receiver 100A shown in Fig. 8. As shown in Fig. 8, the optical receiver 100A includes a carrier 1A, a subcarrier 2A, a PD 3A, a TIA 4A, and a bypass capacitor 5A. High-frequency lines 21A, 22A, and 23A are formed on the subcarrier 2A. The bypass capacitor 5A is connected to an external bias power supply E via a wire L1, and is also connected to the high-frequency line 21 via a wire L2.

[0033] 2 shows the calculation results of the frequency response characteristics of the optical receiver 100 and the optical receiver 100A. In the graph, A represents the frequency response characteristic of the optical receiver 100, and B represents the frequency response characteristic of the optical receiver 100A. The horizontal axis of the graph represents the frequency of the modulation frequency signal.

[0034] Here, the frequency response characteristics depend on the impedance value of the line between the dielectric layer (bypass capacitor) and the PD. In the case of the related optical receiver 100A, the presence of wire L2 between the bypass capacitor 5A and the PD 3 causes excessive peaking in the frequency response characteristics, resulting in bandwidth degradation. As a result, as shown in the graph, the optical receiver 100 has a higher bandwidth than the optical receiver 100A.

[0035] As described above, according to this embodiment, there is no need to provide a wire between the dielectric layer 5 (bypass capacitor) and the PD3, and the distance between the dielectric layer 5 and the PD3 can be sufficiently shortened, thereby realizing an optical receiver 100 having a wide and versatile frequency band.

[0036] [Manufacturing process] Next, the manufacturing process of the optical receiver 100 will be described with reference to Fig. 3. First, as shown in step (1) in the figure, GND vias 2a are formed in the subcarrier 2. Specifically, the GND vias 2a are formed by filling them with copper.

[0037] Next, in step (2), a dielectric layer 5 is formed on top of the GND via 2a so as to be embedded in the subcarrier 2. Specifically, the dielectric layer 5 is formed by crystal growth using a CVD (chemical vapor deposition) method. However, the method for forming the dielectric layer 5 is not limited to this, and any method can be used.

[0038] Next, in step (3), high-frequency lines 21, 22, and 23 are formed on the subcarrier 2. In particular, the high-frequency line 21 is formed so that the lower surface of the high-frequency line 21 and the upper surface of the dielectric layer 5 are in contact with each other.

[0039] Finally, in step (4), PD3 and TIA4 are arranged on subcarrier 2. In this case, the arrangement is such that the bottom surface of the left part of PD3 contacts high-frequency line 21, the bottom surfaces of the right parts of PD3 and TIA4 contact high-frequency line 22, and the bottom surface of the right part of TIA4 contacts high-frequency line 23.

[0040] If the subcarrier 2 is multi-layered, the above steps may be carried out while the subcarrier is being formed.

[0041] However, the configuration and manufacturing process of the subcarrier are not limited to those described above. A modified example of the manufacturing process will be described with reference to Fig. 4. Fig. 4 shows an example in which the subcarrier is made up of a first portion 24 and a second portion 25.

[0042] First, as shown in step (1) in the drawing, the second portion 25 is filled with copper to form the GND via 2a.

[0043] Next, in step (2), the dielectric layer 5 and the high-frequency line 21 are formed in this order on the second portion 25, and the high-frequency lines 22 and 23 are formed on the first portion 24.

[0044] Then, in step (3), the right surface of the second portion 25 is bonded to the left surface of the first portion 24. The bonding method is arbitrary, and the bonding may be performed by a chemical method or a mechanical method.

[0045] Finally, in step (4), PD3 and TIA4 are placed on subcarrier 2.

[0046] [Variations] Furthermore, the configuration in the vicinity of the dielectric layer 5 is not limited to the above. An optical receiver 101 according to a modified example of the first embodiment will be described with reference to FIG.

[0047] In the optical receiver 101, a high-frequency line 26 is provided so as to be in contact with the lower surface of the dielectric layer 5. The high-frequency line 26 has a line portion that extends downward from its left end and functions as a GND.

[0048] The high-frequency lines 21, 26 and the dielectric layer 5 may be configured so as to be able to be attached to the subcarrier 2 as a single unit afterward.

[0049] (Second embodiment) An optical receiver 200 according to the second embodiment of the present disclosure will be described with reference to FIG.

[0050] In the optical receiver 200, the dielectric layer 5 is formed below the GND via 2a so as to be embedded in the subcarrier 2. In other words, the dielectric layer 5 is formed on the surface of the subcarrier 2 opposite to the surface on which the PD 3 and the TIA 4 are provided. In other words, the dielectric layer 5 is formed on the surface of the subcarrier 2 opposite to the surface on which the high-frequency line 21 is provided. Therefore, in the manufacturing process, the direction of crystal growth using the CVD method is opposite to that in step (2) of FIG. 3.

[0051] In this embodiment as well, the PD 3 and the dielectric layer 5 can be connected without using a wire, so that the optical receiver 200 having a wide and versatile frequency band can be realized.

[0052] (Third embodiment) An optical receiver 300 according to a third embodiment of the present disclosure will be described with reference to FIG.

[0053] In the optical receiver 300, a bale-shaped chip capacitor 6 is embedded in the subcarrier 2 instead of the dielectric layer 5. The chip capacitor 6 is embedded in the subcarrier 2 while being sandwiched between high-frequency lines 27 and 28. The chip capacitor 6 is an example of a "dielectric" in the present disclosure.

[0054] In this embodiment as well, the PD 3 and the chip capacitor 6 can be connected without using wires, so that the optical receiver 300 having a wide and versatile frequency band can be realized. [Explanation of symbols]

[0055] 100, 101, 200, 300: Optical receiver 1: Career 2: Subcarrier 2a: GND via 21, 22, 23, 26, 27, 28: High frequency lines 24: Part 1 25:Second part 3:PD 4:TIA 5: Dielectric layer 6: Chip capacitor

Claims

1. A subcarrier and a light receiving element provided on the subcarrier and driven by a voltage supplied from an external power source; a high-frequency line provided on the subcarrier and supplying a voltage to the light-receiving element; a dielectric disposed within the subcarrier; and the light receiving element is in contact with the upper surface of the high-frequency line, an upper surface of the dielectric body contacts a lower surface of the high-frequency line; The lower surface of the dielectric is connected to ground. Optical receiver.

2. A subcarrier and a light receiving element provided on the subcarrier and driven by a voltage supplied from an external power source; a high-frequency line provided on the subcarrier and supplying a voltage to the light-receiving element; a GND via arranged directly below the high-frequency line in the subcarrier; a dielectric disposed within the GND via; An optical receiver having:

3. A subcarrier; a light receiving element provided on the subcarrier and driven by a voltage supplied from an external power source; a high-frequency line provided on the subcarrier and supplying a voltage to the light-receiving element; a dielectric disposed within the subcarrier; and the light receiving element is in contact with the upper surface of the high-frequency line, the dielectric is disposed on a surface of the subcarrier opposite to a surface on which the high-frequency line is provided, a bottom surface of the high-frequency line and an top surface of the dielectric are connected by a GND via; Optical receiver.

4. The dielectric is a chip capacitor.

4. An optical receiver according to claim 1.

5. The subcarrier is provided with a TIA (Transimpedance Amplifier) ​​that supplies a voltage to the light receiving element.

4. An optical receiver according to claim 1.

6. A method for manufacturing an optical receiver having a subcarrier, a light receiving element provided on the subcarrier and driven by a voltage supplied from an external power supply, a high-frequency line provided on the subcarrier and supplying a voltage to the light receiving element, and a dielectric disposed within the subcarrier, comprising: forming the dielectric material in the subcarrier by crystal growth; the light receiving element is connected to an upper surface of the high-frequency line; an upper surface of the dielectric body is connected to a lower surface of the high-frequency line; The lower surface of the dielectric is connected to ground. A method for manufacturing an optical receiver.

7. A method for manufacturing an optical receiver having a subcarrier, a light receiving element provided on the subcarrier and driven by a voltage supplied from an external power supply, a high-frequency line provided on the subcarrier and supplying a voltage to the light receiving element, and a dielectric disposed within the subcarrier, comprising: forming the dielectric by crystal growth on a surface of the subcarrier opposite to a surface on which the high-frequency line is provided; the light receiving element is connected to an upper surface of the high-frequency line; a bottom surface of the high-frequency line and a top surface of the dielectric are connected by a GND via; A method for manufacturing an optical receiver.

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