JP2005106936A - Semiconductor optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor optical module that has a reduced number of optical components and a small space for arranging optical fibers. <P>SOLUTION: The semiconductor optical module includes a semiconductor optical element having optical input and output sections in one end face, an optical input port for making light enter from an input optical fiber, an optical output port making light exit to an output optical fiber, and an optical isolator installed between the input port and the input section and between the output port and the output section. The input port and the output port are installed on the same side. Incident light entered from the input port is made to enter the input section through the optical isolator. Further, outgoing light exited from the output section is made to exit from the output port through the optical isolator. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor optical module, and more particularly to a semiconductor module in which an optical input port and an optical output port are provided on the same side surface.

In a conventional semiconductor optical module having an optical input / output port, an input optical fiber and an output optical fiber are attached at positions facing each other across a semiconductor element included in the semiconductor optical module. In addition, optical components for matching the beam pattern size are separately provided between the input optical fiber and the semiconductor element and between the output optical fiber and the semiconductor element (for example, Non-Patent Document 1). 2).
N. Okada et al. "40Gbit / s Electroabsorption Modulator Module with Driver IC Integrated in a Single Package", OFC 2003, Vol. 2, pp.760-761 (2003) Tatsuo Hatta: Mounting and characteristics of ultrahigh-speed semiconductor optical modulators and photodiodes, Optical Technology Contact, August, pp.12-19 (2003)

In the conventional semiconductor optical module, since the optical components are provided on both sides of the semiconductor element, the element structure is complicated and the manufacturing cost is high.
In addition, since an allowable bending radius is determined for the optical fiber, a space for routing the optical fiber is required on both sides of the semiconductor optical module.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a semiconductor optical module that can reduce the number of optical components and reduce the space for handling optical fibers.

  The present invention includes a semiconductor optical device having a light input portion and a light output portion on one end face, a light input port for allowing light to enter from an input optical fiber, a light output port for emitting light to the output optical fiber, The semiconductor optical module includes an optical isolator provided between the input port and the optical input unit and between the optical output port and the optical output unit. The optical input port and the optical output port are provided on the same side. Incident light that has entered from the optical input port enters the optical input unit through the optical isolator, and emission light that has exited from the optical output unit exits from the optical output port through the optical isolator.

  In the semiconductor optical module according to the present invention, the structure of the optical component can be simplified, and the manufacturing cost can be reduced. In addition, the semiconductor optical module can be miniaturized.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram of a semiconductor optical module according to the present embodiment, the whole being represented by 100. The semiconductor optical module 100 includes a semiconductor element 10. The semiconductor element 10 includes, for example, an optical amplification element or an optical modulation element. The semiconductor element 10 includes a light input unit 11 and a light output unit 12 provided on the same end surface. The semiconductor optical module 100 includes an optical isolator 20 adjacent to the semiconductor element 10. Further, the semiconductor optical module 100 includes an optical input port 31 and an optical output port 32 provided on one side surface. An input optical fiber 41 and an output optical fiber 42 can be connected to the optical input port 31 and the optical output port 32, respectively.

  As shown in FIG. 1, the signal light 1 incident from the input optical fiber 41 through the optical input port 31 passes through the optical isolator 20 and enters the optical input unit 11 of the semiconductor element 10. The optical signal 1 modulated or amplified by the semiconductor element 10 is output from an optical output unit 12 provided on the same end face as the optical input unit 11. The signal light 1 emitted from the optical output unit 11 passes through the optical isolator 20 again, then exits from the optical output port 32, and enters the output optical fiber. Here, a polarization-dependent optical isolator is used as the optical isolator 20, but a polarization-independent optical isolator may be used as will be described later.

FIG. 2 is a schematic diagram showing the structure of the polarization-dependent optical isolator 20. The optical isolator 20 has a structure in which a Faraday rotator 21 having a rotation angle of 45 ° is inserted between a first birefringent crystal 22 and a second birefringent crystal 23 each having two polarizers whose transmission axes are inclined by 45 °. It has become.
The first birefringent crystal 22 and the second birefringent crystal 23 are, for example, parallel birefringent crystals. The Faraday rotator 21 also includes a magnet that applies a magnetic field to the Faraday rotator 21. As shown in FIG. 2, for example, the signal light 1 incident from the optical input port 31 enters the first birefringent crystal 22 from the left side. The signal light 1 that has passed through the first birefringent crystal 22 passes through the Faraday rotator 21 and then enters the semiconductor element 10 from the light input unit 11 through the second birefringent crystal 23. The optical isolator 20 may include a lens that matches the beam pattern sizes at the optical input port 31 and the optical input port 11 and the beam pattern sizes at the optical output port 32 and the optical output port 12.

Next, the operation of the polarization dependent optical isolator 20 included in the semiconductor optical module 100 according to the present embodiment will be described with reference to FIG.
FIG. 3 shows an operation when the signal light 1 incident from the input optical fiber 41 propagates to the semiconductor element 10. In FIG. 3, (a1), (b1), and (c1) are about the optical axis of the incident light to the semiconductor element 10, and (a2), (b2), and (c2) are about the optical axis of the emitted light from the semiconductor element 10. Indicates the direction of the electric field in a vertical plane.
(A1) and (a2) pass through the first birefringent crystal 22, (b1) and (b2) pass through the Faraday rotator 21, and (c1) and (c2) show the second birefringent crystal. The direction of the electric field of the light after passing through 23. In FIG. 3, a circle (◯) indicates the position of the optical input port 31 (alignment position of the optical fiber 41), and a square mark (□) indicates the position of the optical input unit 11.

  First, when non-polarized light enters from the input optical fiber 41, the first birefringent crystal 22 is separated into ordinary light S1 and extraordinary light S2, and is emitted from different locations at the output end of the first birefringent crystal 22 (FIG. 3 (a1)). Here, the ordinary light S1 is at the position (O) of the optical input port 31, and the abnormal light S2 is shifted from the position of the optical input port 31.

  Next, the Faraday rotator 21 rotates the ordinary light S1 and the extraordinary light S2 in the same direction of 45 ° and inputs the same into the second birefringent crystal 23 (FIG. 3 (b1)).

  In the second birefringent crystal 23, the ordinary light S1 and the extraordinary light S2 are further separated and emitted from different places.

  Therefore, by adjusting the optical axis of the semiconductor element (position of the optical input unit 11) with respect to the required polarized light (ordinary light S1 here), only specific polarized light can be passed (FIG. 3 (c1)). )).

  Subsequently, reverse propagation will be described. Here, a case will be described in which the optical axis (position of the light input unit 11) is adjusted so that ordinary light can pass in the forward direction.

  The light propagated in the reverse direction from the light input portion 11 of the semiconductor element passes through the second birefringent crystal 23 and is separated into ordinary light S1 and extraordinary light S2 (FIG. 3 (c2)).

  Next, the Faraday rotator 21 rotates the polarization directions of the ordinary light S1 and the extraordinary light S2 in the same direction by 45 °, and inputs them to the first birefringent crystal 22 (FIG. 3 (b2)).

  In the first birefringent crystal 22, the ordinary light S1 and the extraordinary light S2 are further separated and emitted from different places (FIG. 3 (a2)).

  Comparing FIG. 3 (a1) with FIG. 3 (a2), the optical isolator 20 separates and makes only the ordinary light S1 incident, and inputs light in the reverse direction such as reflected light from the light input unit 11 as light input. It can be seen that the optical isolator functions effectively without returning to the port 31.

  Next, FIG. 4 shows an operation when light emitted from the light output unit 12 of the semiconductor element 10 propagates to the output optical fiber 42. 4, as in FIG. 3 described above, (a1) and (a2) pass through the first birefringent crystal 22, (b1) and (b2) pass through the Faraday rotator 21, ( c1) and (c2) indicate the direction of the electric field of the light in a plane substantially perpendicular to the optical axis after passing through the second birefringent crystal 23. In FIG. 4, a circle (◯) indicates the position of the optical output port 32 (alignment position of the optical fiber 42), and a square mark (□) indicates the position of the optical input unit 12.

  The light emitted from the light input unit 12 passes through the second birefringent crystal 23 and is separated into ordinary light S1 and extraordinary light S2 (FIG. 4 (c1)), and then the direction of the electric field is the same direction by the Faraday rotator 21. And 45 ° (FIG. 4 (b1)), and further passes through the first birefringent crystal 22 (FIG. 3 (a1)). As a result, only the ordinary light S 1 enters the light output port 32 and is emitted from the output optical fiber 42.

  On the other hand, in the reverse propagation, the light separated into the ordinary light S1 and the extraordinary light S2 through the first birefringent crystal 22 (FIG. 4 (a2)) is 45 in the same direction by the Faraday rotator 21. Rotate (° (FIG. 4 (b2))) and pass through the second birefringent crystal 23 (FIG. 4 (c2)). The light transmitted through the second birefringent crystal 23 is emitted to a position away from the light output port 32 for both the ordinary light S1 and the extraordinary light S2.

  As a result, it is understood that effective optical isolation can be obtained even for the signal light emitted from the optical input unit 12.

5A and 5B are optical path diagrams of the polarization-dependent optical isolator 20, wherein FIG. 5A is a top view and FIG. 5B is a side view. In FIG. 5, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts, a solid line indicates a forward optical path, and a broken line indicates a reverse optical path.
As described with reference to FIGS. 3 and 4, when the optical axis is aligned with the normal light S1 in the forward direction (horizontal), the normal light S1 in the reverse direction is output from a place away from the optical axis (FIG. 5 ( a)). That is, the polarization-dependent optical isolator 20 functions as an optical isolator by separating only the ordinary light S1 and making it incident and removing light in the opposite direction such as reflected light from the optical axis. Therefore, bidirectional optical isolation sharing an optical component is possible.
Note that the optical isolator 20 can isolate light on both the input side and the output side of the semiconductor element as shown in FIG.

  As described above, in the semiconductor optical module 100, it is possible to isolate both incident light and outgoing light to the semiconductor element 10 by using one optical isolator 20. For this reason, the optical components contained in the semiconductor optical module 100 can be reduced, and the manufacturing cost can be reduced.

  By using such a polarization-dependent optical isolator, it is possible to reduce the number of optical components and to reduce costs compared to using a polarization-independent optical isolator described later.

FIG. 6 is a perspective view of an optical input / output means for connecting an optical fiber to the semiconductor optical module 100. As shown in FIG. 1, instead of separately connecting the input optical fiber 41 and the output optical fiber 42, the optical input / output fixed to the ferrule 43 so that the input optical fiber 41 and the output optical fiber 42 are substantially parallel to each other. You may connect using the means 42. FIG.
By using the light input / output means 40, the signal light input / output means can be reduced in size, and the semiconductor optical module 100 can be reduced in size.

FIG. 7 is a schematic diagram of the semiconductor element 10 included in the semiconductor optical module 100. The semiconductor element 10 includes a semiconductor substrate 15 provided with a light input unit 11 and a light output unit 12. The semiconductor substrate 15 is provided with a functional unit 14 such as an optical amplification unit or an optical modulation unit. The optical input unit 11, the optical output unit 12, and the functional unit 14 are connected by an optical waveguide 13.
In the semiconductor element 10, the light incident from the light incident portion 11 is reflected by the reflection point 16 of the second end surface 18 facing the first end surface 17 provided with the light input portion 11 and the light output portion 12, and the light output portion. 12 is emitted. A light reflecting film may be provided on the second end face 18.

  Here, although the light that has entered from the light input unit 11 is reflected by the second end face 18 and guided to the light output unit 12, other means such as using a loop-shaped optical waveguide may be used. Absent.

  Thus, in the semiconductor optical module 100 according to the present embodiment, both the incident light / emitted light to the semiconductor element 10 can be isolated by the single optical isolator 20. As a result, the number of optical components used for isolation can be reduced, and the semiconductor optical module 100 can be reduced in size and cost.

  Further, in the semiconductor optical module 100 according to the present embodiment, since the input optical fiber 41 and the output optical fiber 42 are connected to the same side surface (end surface), a space for handling these fibers is provided in the conventional structure. Can be smaller.

Embodiment 2. FIG.
In the present embodiment, a case where a polarization-independent optical isolator is used as the optical isolator 20 of the semiconductor optical module 100 will be described.
8A and 8B are structural views of the polarization-independent optical isolator 20, wherein FIG. 8A is a top view and FIG. 8B is a side view. In the optical isolator 20, a first Faraday rotator 62 and a first half-wave plate 63 are inserted between the first birefringent crystal 61 and the second birefringent crystal 64, and the second birefringent crystal 64 and the third birefringent crystal 64 are further inserted. A second half-wave plate 65 and a second Faraday rotator 66 are inserted between the birefringent crystals 67 to form a structure.
The optical isolator 20 may further include a lens.

  The first birefringent crystal 61, the second birefringent crystal 64, and the third birefringent crystal 67 are made of, for example, a parallel plate birefringent crystal. The ordinary optical axes of the first birefringent crystal 61 and the second birefringent crystal 64 are arranged to be orthogonal to each other, while the ordinary optical axes of the first birefringent crystal 61 and the third birefringent crystal 67 are parallel to each other. Are arranged as follows. The first Faraday rotator 62 and the second Faraday rotator 66 are arranged so that the polarized light rotates in the same direction at an angle of 45 °. Further, each of the first half-wave plate 63 and the second half-wave plate 65 has a structure in which two half-wave plates whose optical axes are orthogonal to each other are stacked one above the other. As will be described later, ordinary light and extraordinary light are separated in the vertical direction and are incident on each of the half-wave plates stacked vertically.

Next, the operation of the polarization-independent optical isolator according to the present embodiment will be described with reference to FIGS.
9 and 10 show the direction of the electric field of light in a plane substantially perpendicular to the optical axis at each of the positions A to H shown in FIG. 8A, and are shown at positions A to H in FIG. The direction of the electric field shown in FIGS. 9 (a1) to (h1) corresponds to the direction of the electric field shown in FIGS. 9 (a2) to (h2). Similarly, the electric field directions shown in FIGS. 10 (a1) to (h1) and the electric field directions shown in FIGS. 10 (a2) to (h2) correspond to positions A to H in FIG. 8, respectively. In FIGS. 9 and 10, a circle (◯) indicates the position of the optical input port 31 (alignment position of the optical fiber 41), and a square mark (□) indicates the position of the optical input unit 11.

First, the case where light propagates in the forward direction from the input optical fiber 41 to the optical input unit 11 of the semiconductor element 10 will be described.
When non-polarized light (FIG. 9 (a1)) enters from the input optical fiber 41, it is separated into ordinary light and extraordinary light in the first birefringent crystal 61, and output from different locations at the output end of the first birefringent crystal 22. (FIG. 9 (b1)).

  The ordinary light and the extraordinary light pass through the first Faraday rotator 62, both of which rotate in the same direction by 45 ° (FIG. 9 (c1)), and enter the first half-wave plate 63. As described above, the first half-wave plate 63 has a structure in which two half-wave plates are vertically stacked, and the separated ordinary light and extraordinary light are incident on each of the half-wave plates stacked vertically. To do. As a result, the polarizations of ordinary light and extraordinary light are respectively rotated in opposite directions (here, 45 °) (FIG. 9 (d1)) and enter the second birefringent crystal 64. From the second birefringent crystal 64, two ordinary lights emerge from the corresponding positions (FIG. 9 (e1)). These lights enter the half-wave plates stacked on the top and bottom of the second half-wave plate 65, respectively, and the polarized light rotates in the opposite direction (here, 45 °) (FIG. 9 (f1)). Further, after passing through the second Faraday rotator 66, the polarized light rotates 45 ° in the same direction (FIG. 9 (g1)), and then enters the third birefringent crystal 67. In the third birefringent crystal 67, ordinary light and extraordinary light entering from different places exit from the same place and enter the light input unit 11 (FIG. 9 (h1)).

  Thus, the unpolarized light incident from the input optical fiber 41 finally enters the light input unit 11 of the semiconductor element 10.

  Subsequently, reverse propagation will be described. Here, a case where the optical axis (position of the light input unit 11) is adjusted so that forward light incident from the input optical fiber 41 is coupled to the light input unit 11 will be described.

  The non-polarized light (FIG. 9 (h2)) propagating in the reverse direction from the light input unit 11 of the semiconductor element 10 passes through the third birefringent crystal 67 and is separated into ordinary light and extraordinary light. It exits from 67 different positions (FIG. 9 (g2)). These lights are both rotated by 45 ° in the same direction by the second Faraday rotator 66 (FIG. 9 (f 2)), and further in the different directions (here 45 by the second half-wave plate 65). °) The polarized light rotates (FIG. 9 (e 2)) and enters the second birefringent crystal 64. From the second birefringent crystal 64, these lights are emitted as two extraordinary lights (FIG. 9 (d2)), and the polarized light rotates in different directions (here 45 °) by the first half-wave plate 63 ( Further, the first Faraday rotator 62 rotates the 45 ° polarized light in the same direction (FIG. 9B 2), and enters the first birefringent crystal 61. From the first birefringent crystal 61, ordinary light and extraordinary light are emitted from different positions from the light input port 41 (FIG. 9 (a2)).

  Thus, the forward non-polarized light entering from the input optical fiber 41 is incident on the semiconductor element 10 from the optical input unit 11, while the non-polarized light in the reverse direction from the optical input unit 11 to the input optical fiber 41. Since no light enters the input optical fiber 41, effective optical isolation is possible.

  Subsequently, FIG. 10 shows an operation when light emitted from the light output unit 12 of the semiconductor element 10 propagates to the output optical fiber 42. Also in FIG. 10, similarly to FIG. 9 described above, (a1) to (h1) and (a2) to (h2) are respectively the light in a plane substantially perpendicular to the optical axis in A to H of FIG. Indicates the direction of the electric field.

  The light emitted from the light input unit 12 (FIG. 10 (h1)) was separated into ordinary light and extraordinary light from the third birefringent crystal 67, through the second Faraday rotator 66, the second half-wave plate 65, and the like. Thereafter, the ordinary light and the extraordinary light are finally emitted from the same position to the output optical fiber 42 (FIG. 10 (a1)).

On the other hand, in the reverse propagation, the light entering the first birefringent crystal 61 (FIG. 10 (a2)) is separated into ordinary light and extraordinary light (FIG. 10 (b2)), the first Faraday rotator 62, The light passes through the first half-wave plate 63 and the like, and is emitted to a position different from the light output unit 12 of the semiconductor element 10 (FIG. 10 (h2)).
As a result, it is understood that effective optical isolation can be obtained even for the signal light emitted from the light output unit 12.
Also in FIG. 10, the rotation of polarized light in the Faraday rotator and the half-wave plate is the same as in FIG.

11A and 11B are optical path diagrams of the polarization-independent optical isolator 20, wherein FIG. 11A is a top view and FIG. 11B is a side view. In FIG. 11, the same reference numerals as those in FIG. 8 indicate the same or corresponding parts, the solid line indicates the forward optical path, and the broken line indicates the reverse optical path.
As shown in the side view of FIG. 11B, when viewed from the side, the light incident on the optical isolator 20 is split into two optical paths by polarization, but the input / output positions are the same. However, as shown in FIG. 11A, when viewed from above, the optical path in the forward direction and the reverse direction is changed from the second birefringent crystal 64. Therefore, the use of the optical isolator 20 enables bidirectional light isolation sharing the optical component.

  Thus, in the semiconductor optical module 100, isolation can be performed with only one polarization-independent optical isolator, and the optical components included in the semiconductor optical module 100 can be reduced, thereby reducing the manufacturing cost.

It is the schematic of the semiconductor optical module concerning Embodiment 1 of this invention. It is the schematic of the optical isolator contained in a semiconductor optical module. It is a figure which shows operation | movement of a polarization dependence type optical isolator. It is a figure which shows operation | movement of a polarization dependence type optical isolator. It is an optical path diagram of a polarization-dependent optical isolator. It is a perspective view of the optical input / output means contained in a semiconductor optical module. It is the schematic of the semiconductor element contained in a semiconductor optical module. It is the schematic of the optical isolator contained in a semiconductor optical module. It is a figure which shows operation | movement of a polarization independent type optical isolator. It is a figure which shows operation | movement of a polarization independent type optical isolator. It is an optical path diagram of a polarization independent type optical isolator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor element, 11 Optical input part, 12 Optical output part, 20 Optical isolator, 31 Optical input port, 32 Optical output port, 41 Input optical fiber, 42 Output optical fiber, 100 Semiconductor optical module

Claims (7)

A semiconductor optical device having a light input portion and a light output portion on one end surface;
An optical input port for entering light from the input optical fiber;
An optical output port for emitting light to the output optical fiber;
An optical isolator provided between the optical input port and the optical input unit and between the optical output port and the optical output unit,
The optical input port and the optical output port are provided on the same side surface,
Incident light incident from the optical input port enters the optical input unit through the optical isolator, and emitted light from the optical output unit exits from the optical output port through the optical isolator. A semiconductor optical module. 2. The optical isolator according to claim 1, wherein the optical isolator includes at least a Faraday rotator and a birefringent crystal, and includes one optical isolator that isolates both the incident light and the emitted light. Semiconductor optical module. 2. The semiconductor optical module according to claim 1, wherein the optical isolator is a single optical isolator on the optical axes of both the incident light and the outgoing light. The semiconductor optical module according to claim 1, wherein the optical isolator is a polarization-dependent optical isolator. 4. The semiconductor optical module according to claim 1, wherein the optical isolator is a polarization independent optical isolator. 2. The semiconductor light according to claim 1, wherein light entering from the light input portion is reflected at or near another end face arranged opposite to the end face and exits from the light output portion. module. 2. The semiconductor optical module according to claim 1, further comprising light input / output means fixed to a ferrule so that the input optical fiber and the output optical fiber are substantially parallel to each other.

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