Optical connection component for optical transceiver module

Abstract

An object of the present disclosure is to easily cope with different optical characteristics of a light source and a light receiver.SOLUTION: The present disclosure includes a plurality of transmission light sources and a plurality of light receivers arranged on one surface of a substrate, an optical fiber array in which an optical fiber provided for each of the plurality of transmission light sources and the plurality of light receivers is arranged, a reflection surface that reflects light from the plurality of transmission light sources and light from the optical fiber array, and a first GRIN lens that is arranged between the reflection surface and the plurality of transmission light sources and has the same number as the plurality of transmission light sources. A second GRIN lens equal in number to the plurality of light receivers, wherein the first GRIN lens and the second GRIN lens are equal in lens length and different in refractive index distribution constant.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a technique for connecting a light source and a light receiver to a fiber array in an optical transceiver module. [Background technology]

[0002] Optical communications and optical data communications often use optical transceiver modules that convert electrical data signals into light and vice versa. In particular, in optical communications at data centers, the introduction of optical transceiver modules capable of transmitting information at high speeds is rapidly increasing in order to process the rapidly increasing amount of information used in AI, image transmission, IoT, autonomous driving, and other applications.

[0003] For this reason, there is strong market demand for smaller and more power-efficient optical transceiver modules, and low-profile modules with reduced module height have been standardized. The latter achieves reduced power consumption by miniaturizing the elements.

[0004] Optical transceiver modules are equipped with a light source for transmission and a light receiver for reception, and it is common to have multiple channels to increase the data volume per module. For example, the QSFP-100GBASE-SR4 transceiver module, which is mainstream in network equipment, is equipped with four light sources and four receivers. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7360695 Summary of the Invention [Problem to be solved by the invention]

[0006] Low-profile modules having multiple channels have been proposed (see, for example, Patent Document 1), but the following method is currently being used. First method: Prepare multiple spherical lenses molded in a resin material for transmission and reception, align them with the light source and receiver in their designated positions, and after reflection, input the light into the optical fiber using a spherical lens molded in another resin material. Second method: Bend the optical fiber and physically connect the end face of the optical fiber to the light source and the light receiver.

[0007] Regarding the second method, it is difficult to achieve a low height, and it is thought that it will become difficult to apply it to optical transceiver modules, which are expected to become increasingly smaller in the future.

[0008] For the first method, the optical characteristics (NA, beam diameter, etc.) of the light source and the photodetector are different, so the optimal solution for the optical system required for each is naturally different. Also, when the bottom surface of the light source and photodetector board is used as the reference, the thicknesses of the light source and photodetector components are different, so the distance between the spherical lens and each component also differs, so the mounting must be devised. [Means for solving the problem]

[0009] In order to achieve these objectives, the transceiver module of the present disclosure comprises a plurality of transmitting light sources and a plurality of optical receivers arranged on one side of a substrate, an optical fiber array in which optical fibers provided for each of the plurality of transmitting light sources and the plurality of optical receivers are arranged, a reflective surface that reflects light from the plurality of transmitting light sources and light from the optical fiber array, first GRIN lenses arranged between the reflective surface and the plurality of transmitting light sources, the number of which is equal to that of the plurality of transmitting light sources, and second GRIN lenses arranged between the reflective surface and the plurality of optical receivers, the number of which is equal to that of the plurality of optical receivers, and the first GRIN lens and the second GRIN lens have the same lens length but different optical characteristics.

[0010] The first GRIN lens and the second GRIN lens may have the following configurations. (i) The refractive index distribution constants are different. (ii) The lens diameter is different. (iii) The refractive index distribution constant and the GRIN lens diameter are different.

[0011] The transceiver module of the present disclosure may further include third and fourth GRIN lenses between the reflecting surface and each optical fiber in the optical fiber array. In this configuration, the third GRIN lens, located in the optical path including the first GRIN lens, focuses the light reflected by the reflecting surface onto the end face of the optical fiber. The fourth GRIN lens, located in the optical path including the second GRIN lens, converts the light from the optical fiber into parallel light and outputs it to the reflecting surface.

[0012] The above disclosures can be combined as much as possible. [Effects of the Invention]

[0013] The present disclosure makes it easy to accommodate different optical characteristics between a light source and a light receiver, and therefore makes it possible to provide an optical transceiver module with low loss and high productivity. [Brief explanation of the drawings]

[0014] [Figure 1] 1 illustrates an example embodiment of an optical transceiver module according to the present disclosure. [Figure 2] An example of the optical paths of the GRIN lenses 21 and 22 is shown. [Figure 3] An example of the relationship between the pitch length P and the refractive index distribution constant g is shown below. [Figure 4] 1 illustrates an example embodiment of an optical transceiver module according to the present disclosure. [Figure 5] An example of the optical paths of the GRIN lenses 21 and 22 is shown. [Figure 6] 1 illustrates an example embodiment of an optical transceiver module according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] The transceiver module of the present disclosure employs the following configuration. First configuration: The optical connection components include GRIN lenses with different refractive index distribution constants that are compatible with the optical system that is optimal for the light source and the photodetector, all in the same matrix. Second configuration: The optical connection components include GRIN lenses with different diameters that are compatible with the optical system that is optimal for the light source and the photodetector, all in the same matrix. Third configuration: The optical connecting parts include GRIN lenses with different refractive index distribution constants and GRIN lens diameters that are suitable for the optical system that is optimal for the light source and the photodetector, all in the same matrix.

[0017] An example of configuring an optical connecting part using an optical fiber array and a GRIN lens array will be described in detail below.

[0018] (First embodiment) 1 shows an embodiment of an optical transceiver module according to the present disclosure. In the optical transceiver module of this embodiment, N optical receivers 31 and N transmitting light sources 32 are arranged in a row on one side of a substrate 33. The optical receivers 31 are any means capable of receiving an optical signal, such as a photodiode (PD). The transmitting light sources 32 are any light sources capable of transmitting an optical signal, such as a vertical cavity surface emitting laser (VCSEL). N is a natural number of 2 or more, and in this embodiment, N=4 is shown as an example.

[0019] The optical transceiver module of this embodiment includes an optical fiber array 91. The optical fiber array 91 has a plurality of optical fibers 11 fixed at their sides by capillaries 12. The end faces of the optical fiber array 91 are beveled, and a reflecting surface 13 is provided on the surface. This allows light that has passed through the capillaries 12 to be incident on the end faces of the optical fibers 11 that are arranged on the reflecting surface 13.

[0020] The optical transceiver module of this embodiment includes a GRIN lens array 92 between a plurality of photodetectors 31 and a plurality of transmitting light sources 32 and an optical fiber array 91. The GRIN lens array 92 includes the same number of GRIN lenses 21 as the number of photodetectors 31, and the same number of GRIN lenses 22 as the number of transmitting light sources 32. The circumferential direction of the GRIN lenses 21 and 22 is covered by a common capillary 23. The GRIN lenses 22 and 21 function as a first GRIN lens and a second GRIN lens, respectively.

[0021] 2 shows an example of the optical paths of the GRIN lenses 21 and 22. In this embodiment, the normal to the light receiving surface of the optical receiver 31 and the emission direction of the transmitting light source 32 are arranged perpendicular to the substrate 33. The optical axis of the GRIN lens 22 coincides with the emission direction of the transmitting light source 32, and the optical axis of the GRIN lens 21 coincides with the incident direction of the optical receiver 31.

[0022] The lens length of the GRIN lenses 21 and 22 is the thickness H of the capillary 23. 23 The GRIN lens 21 reflects the light L emitted from the end face of the optical fiber 11. 21 The GRIN lens 22 has optical properties such that the light L emitted from the transmitting light source 32 is condensed on the light receiving surface of the light receiver 31. 22 The optical fiber 11 has an optical characteristic such that the light L emitted from the transmitting light source 32 is condensed at the end face of the optical fiber 11, i.e., the reflecting surface 13. 22 is incident on the optical fiber 11, and the light L emitted from the optical fiber 11 21 is received by the photoreceiver 31.

[0023] Here, the height H from the bottom surface 34 of the substrate to the light receiving surface of the light receiver 31 31 , and the height H from the bottom surface 34 of the substrate to the output end surface of the transmitting light source 32 32 In this disclosure, the height H 31 and H 32 Even if the optical characteristics of the GRIN lenses 21 and 22 are different, the light L emitted from the optical fiber 11 can be adjusted by adjusting the optical characteristics of the GRIN lenses 21 and 22. 21 is incident on the light receiver 31, and light L emitted from the transmitting light source 32 is 22 can be made to enter the optical fiber 11.

[0024] Furthermore, there may be a gap between the GRIN lens 21 and the light receiver 31, and a gap between the GRIN lens 22 and the transmitting light source 32. In the present disclosure, even if a liquid such as a refrigerant is present in the gap, the optical characteristics of the GRIN lenses 21 and 22 can be adjusted to prevent the light L emitted from the optical fiber 11 from being scattered. 21 is incident on the light receiver 31, and light L emitted from the transmitting light source 32 is 22 can be made to enter the optical fiber 11.

[0025] Furthermore, there is a preferred range of the beam diameter incident on the light receiving surface of the light receiver 31. In this embodiment, by adjusting the pitch length of the GRIN lens 21, the light L emitted from the optical fiber 11 can be 21 can be made to be incident on the light receiving surface of the light receiver 31 with a preferred beam diameter.

[0026] Here, the pitch length is the period when light rays travel through the GRIN lens in a sinusoidal wave pattern. The pitch length P (mm) and the refractive index distribution constant g (mm -1 ) have the following relationship: (Number 1) P=2π / g (1)

[0027] This relationship is illustrated in Figure 3. Figure 3 shows two ray trajectories with different incident points. The pitch length P has characteristics that are directly related to the refractive index distribution constant g. On the other hand, when the central refractive index is constant, the lens diameter is inversely proportional to the refractive index distribution constant g. Therefore, the pitch length can be adjusted by adjusting at least either the lens diameter or the refractive index distribution constant.

[0028] The beam diameter emitted from the transmitting light source 32 varies depending on the transmitting light source 32. In this embodiment, the pitch length of the GRIN lens 21 is adjusted to suit the beam diameter of the transmitting light source 32, thereby 22 can be accurately incident on the optical fiber 11.

[0029] In addition, the height H 31 and height H 32 The GRIN lens 21 and the light receiver 31, and the GRIN lens 22 and the transmitting light source 32 may be connected without any gaps.

[0030] Furthermore, the multiple photodetectors 31 and the multiple light sources for transmission 32 may be mounted on different substrates. Furthermore, the arrangement of the multiple photodetectors 31 and the multiple light sources for transmission 32 is not limited to one row, but may be arranged in any two-dimensional shape.

[0031] As described above, the GRIN lens array 92 of this embodiment has a height H 31 and height H 32 A single optical component can be used to accommodate different optical characteristics of the transmitting light source 32 and the optical receiver 31. This allows the transmitting light source 32 and the optical receiver 31 to be connected to the optical fiber 11 very efficiently.

[0032] (Second embodiment) 4 shows an embodiment of the optical transceiver module of the present disclosure. The optical transceiver module of this embodiment uses the reflecting surface 13 provided on the prism 94. This makes it possible to configure the optical fiber array 91 of the first embodiment by connecting a regular optical fiber array 95 to the prism 94 without processing the optical fiber array 91 itself.

[0033] 5 shows an example of the optical paths of the GRIN lenses 21 and 22. In this embodiment, an example is shown in which the end faces of the capillaries 52, on which the end faces of the optical fibers 51 are arranged in the optical fiber array 95, are perpendicular to each other. In this embodiment, the end faces of the optical fibers 11 are spaced apart from the reflecting surface 13. For this reason, in this embodiment, the pitch lengths of the GRIN lenses 21 and 22 are designed taking into account the optical path length in the prism 94.

[0034] In this embodiment, the light L emitted from the transmitting light source 32 22 After being shaped into a beam by the GRIN lens 22, the light L is reflected by the reflecting surface 13 in the prism 94, passes through the prism 94, and then enters the optical fiber 11. On the other hand, the light L emitted from the optical fiber 11 21 is reflected by the reflecting surface 13 in the prism 94, passes through the prism 94, is shaped into a beam by the GRIN lens 21, and is received by the photodetector 31.

[0035] (Third embodiment) 6 shows an example embodiment of an optical transceiver module according to the present disclosure. The optical transceiver module of this embodiment includes a GRIN lens array 96 between a prism 94 and an optical fiber array 95. The GRIN lens array 96 includes GRIN lenses 61 and 62. The GRIN lens 61 functions as a third GRIN lens located in an optical path including the first GRIN lens 21. The GRIN lens 62 functions as a fourth GRIN lens located in an optical path including the second GRIN lens 22.

[0036] The GRIN lens 61 reflects the light L from the optical fiber 51. 21 The light L is converted into parallel light and emitted to the reflecting surface 13.21 The GRIN lens 62 converts the light L reflected by the reflecting surface 13 into parallel light. 22 The light is focused onto the end face of the optical fiber 51.

[0037] In this embodiment, since the GRIN lenses 61 and 62 are provided, the light L reflected by the reflecting surface 13 21 and L 22 Therefore, the optical fiber 51 and the optical receiver 31 and the transmitting light source 32 and the optical fiber 51 can be optically coupled efficiently.

[0038] (Other embodiments) In the above description and drawings, a VCSEL is shown as an example of the transmitting light source 32, but this is not limiting. Furthermore, the emission direction from the transmitting light source 32 and the incidence direction to the optical receiver 31 are shown as being perpendicular to the surface of the board on which the transmitting light source 32 and the optical receiver 31 are mounted, but it goes without saying that emission and incidence horizontally and at a certain angle relative to the board surface are also included. [Industrial Applicability]

[0039] The optical connecting part according to the present disclosure can be applied to an optical transmitting and receiving module. [Explanation of symbols]

[0040] 11, 51: Optical fiber 12, 23, 33, 52, 63: Capillary 13: Reflective surface 21, 22, 61, 62: GRIN lenses 31:Receiver 32: Transmitting light source 33: Circuit board 34: Bottom 91, 95: Optical fiber array 92, 96: GRIN lens array 94: Prism

Claims

1. a plurality of light sources for transmission and a plurality of light receivers arranged on one surface of a substrate; an optical fiber array in which optical fibers provided for the plurality of transmitting light sources and the plurality of light receivers are arranged; a reflecting surface that reflects light from the plurality of transmitting light sources and light from the optical fiber array; a first GRIN lens disposed between the reflecting surface and the plurality of transmitting light sources, the number of which is equal to the number of the plurality of transmitting light sources; a second GRIN lens disposed between the reflecting surface and the plurality of optical receivers, the number of which is equal to the number of the plurality of optical receivers; Equipped with the first GRIN lens and the second GRIN lens have the same lens length but different optical characteristics; Transmitting and receiving module.

2. The first GRIN lens and the second GRIN lens have different refractive index distribution constants. The transceiver module according to claim 1 .

3. The first GRIN lens and the second GRIN lens have different lens diameters. The transceiver module according to claim 1 .

4. The first GRIN lens and the second GRIN lens have different refractive index distribution constants and GRIN lens diameters. The transceiver module according to claim 1 .

5. a third and a fourth GRIN lens are further provided between the reflecting surface and each optical fiber of the optical fiber array; the third GRIN lens, which is disposed in an optical path including the first GRIN lens, focuses the light reflected by the reflecting surface onto an end face of the optical fiber; the fourth GRIN lens, which is disposed in an optical path including the second GRIN lens, converts the light from the optical fiber into parallel light and outputs the parallel light to the reflecting surface; The transceiver module according to claim 1 .

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