JP2008003211A - In-line type hybrid optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that the structure of a conventional hybrid optical device including an optical isolator has a complicated package, and a highly accurate positioning is required in an assembly process. <P>SOLUTION: The in-line type hybrid optical device 1 is composed a reflection type optical isolator 2 having a reflection mirror 11 composed of a half mirror 11b on the other end and a light receiving element 3 arranged on the light transmission side of the refection mirror 11, which are housed in an isolator case 20 and in a light receiving element case 30, respectively, and the respective cases 20 and 30 are positioned and fixed so that the reflection type optical isolator 2 and the light receiving element 3 are optically coupled with collimated light. Approximately 95% of incident light signal A is reflected as reflected light R from the reflection mirror 11 toward an input/output optical fiber 16 side, and approximately 5% of the incident light signal A passes through as transmission light T toward a light transmission side. The transmission light T propagates as collimated light and is made incident on the light receiving face 3a of the light receiving element 3 via a hemispherical face lens 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inline hybrid optical device including an inline reflective optical isolator section and an optical active element.

  In recent years, with the rapid development of optical communication due to the spread of so-called FTTH (Fiber to the home) connection services, etc., in order to compensate for optical signal transmission loss and optical signal strength decrease due to optical signal branching, The introduction of optical fiber amplifiers that directly amplify optical signals without converting them into electrical signals is advancing. In general, optical fiber amplifiers are composed of optical functional elements such as polarization-independent optical isolators, pumping semiconductor laser light sources, optical multiplexers, optical splitters, and monitoring light receiving elements in addition to optical fibers for amplification. The optical signal in the optical fiber is amplified by the pumping light (pump light) output from the pumping semiconductor laser light source.

  Conventionally, an optical fiber amplifier has been configured by interconnecting each of these single-function optical components with an optical fiber. When an optical fiber amplifier is configured in this manner, the number of components increases. As the assembly process increases, there is a problem that the connection loss increases with the increase in the number of connection parts of the optical components. In addition, such an increase in the number of parts and the number of connected parts has caused an increase in the manufacturing cost of the optical fiber amplifier and an increase in the size of the optical fiber amplifier.

  The increase in the manufacturing cost and the increase in size of the optical fiber amplifier described above become a particularly serious problem when a large amount of optical fiber amplifier is used in an optical access system such as FTTH connection service. As one of the measures to solve this problem, each optical component is arranged on a strong substrate together with optical elements such as a lens and a mirror without connecting the optical components to each other using an optical fiber or the like. However, there is a method of optical coupling in a spatial system. However, this measure requires a submicron positional accuracy for the placement of each optical component, and thus has a drawback that the reliability of the optical fiber amplifier is likely to be problematic, and the manufacturing cost is high.

  Therefore, in recent years, as an effective measure for solving the above-described problem, a measure using a component in which a part of optical components constituting an optical fiber amplifier is integrated, that is, a hybrid optical device is employed. In particular, multifunctional optical devices that combine optical isolators, which are major components, and optical filters such as optical multiplexers / demultiplexers and optical splitters, and optical isolators, optical filters, and optical active elements such as semiconductor lasers and light receiving elements. A hybrid optical device is useful. Here, the “photoactive element” means an element using electricity such as LD (laser diode), LED (light emitting diode), PD (photodiode), etc. Elements that do not use electricity, such as optical couplers and optical splitters, are called “optical passive elements”. Several such hybrid optical devices have been provided as commercial products. Among them, an inline hybrid optical device in which a reflective inline optical isolator and an optical active element are connected in series is an assembly operation. It is easy to handle because the input / output optical fiber is taken out on one side of the optical device, and has many advantages such as downsizing the apparatus and reducing the manufacturing cost.

  Conventionally, as the above-described reflection type inline optical isolator, there are those disclosed in Patent Document 1 and Patent Document 2. Moreover, as a hybrid optical device using a reflective inline optical isolator, for example, there are those disclosed in Non-Patent Document 1 and Patent Document 3. In addition, techniques for simply combining a reflective in-line optical filter and an optical active element are disclosed in Patent Document 4, Patent Document 5, Patent Document 6, and the like.

  In the hybrid optical device for an optical fiber amplifier disclosed in Non-Patent Document 1, a first cylindrical gradient index lens (hereinafter referred to as a rod lens) disposed on the input / output optical fiber side and an optical signal observation Since the second rod lens arranged on the monitor PD (photodiode) side of the first optical lens is optically coupled by the collimated light system, the alignment between the first rod lens and the second rod lens is as follows. Since the tolerance of the relative position error is large, it can be performed relatively easily. However, the second rod lens and the monitor PD are not optically coupled by a collimated light system but are optically coupled by a so-called light collecting system. For this reason, the optical coupling efficiency between the second rod lens and the monitor PD is greatly influenced by the relative positional relationship between them, and the alignment between the second rod lens and the monitor PD is High positional accuracy is required as compared with the alignment between the first rod lens and the second rod lens.

  Further, in the hybrid optical device for optical fiber amplifier disclosed in Patent Document 3, the first, second, and third rod lenses located on the light input side with respect to the reflector plate constitute a part of the optical isolator. The light receiving element is provided on the light output side of the reflecting plate via the fourth rod lens.

Also in the hybrid optical device for an optical fiber amplifier disclosed in Patent Document 3, the alignment between the fourth rod lens and the light receiving element is configured to be optically coupled by a condensing system. Similar to the disclosed hybrid optical device for an optical fiber amplifier, high relative positional accuracy is required.
Japanese Patent No. 2710451 (FIGS. 1, 2 and 3) Japanese Patent Laying-Open No. 2005-17904 (FIGS. 1, 2, 3, and 4) Japanese Patent Application Laid-Open No. 7-301763 (paragraphs [0070] to [0076]) JP-A-62-269909 (FIG. 1) JP 2000-338359 A (paragraphs [0010] to [0014]) JP 2004-221420 A (paragraphs [0020] to [0028]) Proceedings of Spring Meeting of 1993 IEICE (C-200, 4-236)

  However, in conventional hybrid optical devices for optical fiber amplifiers as shown in Non-Patent Document 1 and Patent Document 3 above, a configuration in which a plurality of rod lenses are connected in series with an optical element such as a birefringent plate interposed therebetween Therefore, the alignment between the light receiving element and the rod lens facing the light receiving element cannot be performed unless the alignment between the rod lenses is completed. Therefore, it is necessary to first perform alignment between rod lenses that do not require relatively high accuracy, and finally assemble rod lenses and light receiving elements that require highly accurate alignment. In order to prevent this, it is necessary to align the rod lens and the light receiving element in advance and fix them. However, since the mounting position of the light receiving element largely depends on the incident position of the signal light to the rod lens, it is difficult to align the light receiving element and the lens facing the light receiving element alone. This is not realistic because the three lenses, the rod lens and the light receiving element, facing the optical isolator portion and the light receiving element are simultaneously aligned. In general, a rod lens is not often used for a lens that collects an optical signal on a light receiving element.

  As a result, the structure of the hybrid optical device for an optical fiber amplifier as shown in the above-mentioned Non-Patent Document 1 and Patent Document 3 is manufactured so that the package becomes complicated and a high degree of alignment is required in the assembly work process. It becomes a factor which raises cost, and becomes a factor which makes it easy to make optical coupling unstable. In addition, these factors further tend to deteriorate the optical characteristics, leading to inferior reliability.

The present invention has been made to solve such a problem, and has an optical signal input terminal and an output terminal at one end, reflects an optical signal incident from the input terminal to the output terminal side, and enters the optical signal. An inline-type reflective optical isolator having a reflecting means at the other end for transmitting a part of
An optical active element disposed on the light transmitting side of the reflecting means;
An in-line hybrid optical device configured with
The optical active element converts the condensing state of the light transmitted through the reflecting means or the light emitted to the reflecting means on the side facing the reflecting means, for example, a condensing means such as a spherical lens, an aspherical lens, or a fused lens. Prepared,
In the reflective optical isolator section and the optical active element, the optical axis of the light reflected by the reflecting means or the optical axis of the light transmitted through the reflecting means and the optical axis of the optical active element via the condensing means match or substantially match. The reflection type optical isolator section and the optical active element are fixed to each other so as to be optically coupled by collimated light.

  According to this configuration, the optical axis of the light reflected by the reflecting means or the optical axis of the light transmitted through the reflecting means and the optical axis of the optical active element coincide or substantially coincide with each other. The element is optically coupled by collimated light. Therefore, the light emitted from the active optical element and reflected by the reflecting means together with the light emitted to the reflective optical isolator section, and the light transmitted through the reflecting means and incident from the reflective optical isolator section to the optical active element The mode field becomes almost parallel light and the mode field diameter becomes large. As a result, the tolerance of the relative alignment error in the three-axis (XYZ-axis) direction between the reflective optical isolator section and the optical active element is improved. Accordingly, the optical axis between the reflection type optical isolator part and the optical active element can be obtained simply by accurately adjusting the angle of the optical axis of the optical active element with respect to the reflection means and fixing the reflection type optical isolator part and the optical active element to each other. As a result, the condensing means for the optical active element is previously integrated with the reflection type optical isolator portion, and this integrated reflection type optical isolator is used. Therefore, it is not necessary to align the optical active element not provided with the light collecting unit with the optical coupling system. As a result, an in-line hybrid optical device is provided in which the package structure is relatively simplified, the optical characteristics are stable, and the manufacturing cost can be suppressed.

  Further, the present invention is characterized in that the reflecting means comprises a half mirror that transmits the intensity of the optical signal incident from the input terminal, and the optical active element comprises a light receiving element.

  According to this configuration, the optical signal incident from the input terminal is split in light intensity into an optical signal reflected by the half mirror and an optical signal transmitted through the half mirror, and the optical signal transmitted through the half mirror is received by the light receiving element. Is done. For this reason, the optical signal incident on the reflective optical isolator from the input terminal is observed based on the optical signal received by the light receiving element. Further, when the optical active element is a light receiving element, the angle alignment of the optical axis of the optical active element with respect to the reflecting means can increase the area of the light receiving surface of the light receiving element. The degree is relatively large compared to other photoactive elements. For this reason, the relative alignment between the optical isolator portion and the optical active element can be more reliably and easily performed.

  According to the present invention, the reflecting means includes a wavelength selection filter that transmits an optical signal in a specific wavelength region, for example, an optical signal in the vicinity of a wavelength of 1480 nm, and the optical active element is at least one of the light receiving element and the light emitting element. It is characterized by comprising the above elements.

  According to this configuration, the reflection type optical isolator unit is optically coupled with an optical active element composed of an element such as a light receiving element or a light emitting element, and the optical active element has various functions for optical signals in a specific wavelength region. Further, it is possible to add value to the optical signal isolated by the reflection type optical isolator section, or to use a part of the isolated optical signal.

  Further, the present invention provides an optical material in which the reflecting means has a wedge-shaped cross section perpendicular to a plane including the optical axis of the optical signal incident from the input terminal and the optical axis of the optical signal output to the output terminal. A reflection member that reflects an optical signal and partially transmits the optical signal is provided on a surface facing the optical active element.

  According to this configuration, the optical signal incident from the input terminal is reflected and partially transmitted by the reflecting member provided on the surface facing the optical active element of the optical material constituting the reflecting means. Since the reflecting member is provided on the surface of the optical material that is inclined with respect to the traveling direction of the optical signal incident from the input terminal, the reflection light is reflected by the light that is multiply reflected by the surface facing the optical active element of the optical material. It is prevented that the optical characteristics in the isolator section are affected.

  According to the inline-type hybrid optical device of the present invention, as described above, the angle of the optical axis of the optical active element with respect to the reflecting means is accurately adjusted, and the reflective optical isolator portion and the optical active element are simply fixed to each other. The optical coupling between the reflective optical isolator and the optical active element can be performed reliably and easily, the package structure is relatively simplified, the optical characteristics are stable, and the manufacturing cost is reduced. An in-line hybrid optical device that can be suppressed is provided.

  Next, the best mode for carrying out the present invention will be described.

  FIG. 1 is a partially broken side view showing the internal structure of the inline-type hybrid optical device 1 according to the present embodiment. 2 shows a schematic configuration of the reflective optical isolator 2 shown in FIG. 1. FIG. 2A is a plan view thereof, and FIG. 2B is a side view thereof. In FIG. 2, the same parts as those in FIG.

  As shown in FIG. 1, the inline-type hybrid optical device 1 includes an inline-type reflective optical isolator 2 and a light receiving element 3.

  The reflective optical isolator 2 includes a two-core ferrule 4, a rutile plate 5, a quartz glass plate 6 (not shown in FIG. 1) and a half-wave plate 7, a converging rod lens 8, a spacer 9, a magnetized garnet crystal plate 10, and a reflection. The mirrors 11 are arranged in this order.

  Input / output optical fibers 15 and 16 whose optical axes are parallel to each other are arranged in parallel at an interval of 125 [μm] and integrated with the two-core ferrule 4. The reflection type optical isolator 2 is configured to emit an optical signal incident from one input / output optical fiber 15 (or input / output optical fiber 16) from the other input / output optical fiber 16 (or input / output optical fiber 15). ing. The one ends 15a and 16a of the input / output optical fibers 15 and 16 are connected to an external optical signal path (not shown), and an optical signal input terminal and an output terminal provided at one end of the reflective optical isolator 2, respectively. It is composed. The other ends 15 b and 16 b of the input / output optical fibers 15 and 16 are disposed on the end face 4 a of the two-core ferrule 4. The end face 4a of the two-core ferrule 4 is formed to be inclined at a predetermined angle (for example, 8 °) with respect to a plane perpendicular to the optical axes of the input / output optical fibers 15 and 16. The rutile plate 5, the quartz glass plate 6, and the half-wave plate 7 are disposed so as to be inclined so that their respective light input / output end faces are parallel to the end face 4 a of the two-core ferrule 4. Further, the end face 8 a facing the quartz glass plate 6 and the half-wave plate 7 of the converging rod lens 8 is formed so as to be substantially parallel to the end face 4 a of the two-core ferrule 4.

  The rutile plate 5 is made of a rutile crystal which is a birefringent crystal, and separates an optical signal A incident from the forward direction indicated by an arrow in FIG. 2A into an ordinary ray O and an extraordinary ray E (FIG. 2A). ), (B)). The crystal optical axis 5c of the rutile plate 5 is oriented in the direction indicated by the arrow in FIG. 2B, and an ordinary ray O or extraordinary ray E of an optical signal having a polarization in a direction parallel to the crystal optical axis 5c. A spatial displacement 5d is made to act on.

  Between the rutile plate 5 and the converging rod lens 8, the ordinary ray O and the extraordinary ray E are transmitted to the position where the optical signal A incident from the input / output optical fiber 15 passes, depending on the forward or reverse propagation direction. A half-wave plate 7 that rotates the polarization direction in reverse is disposed. Further, a quartz glass plate 6 which is an amorphous optical element is disposed at a position where an optical signal (reflected light R) reflected by the reflecting mirror 11 and incident on the input / output optical fiber 16 passes. The quartz glass plate 6 is arranged in parallel with the half-wave plate 7 so that only the reflected light R reflected from the reflecting mirror 11 passes in the forward operation. The optical axis of the half-wave plate 7 is oriented at an angle of 22.5 ° counterclockwise with respect to the polarization direction of the ordinary ray O that is separated and traveling in the forward direction. When A propagates in the forward direction indicated by the arrow in FIG. 2A, the polarization directions of the ordinary ray O and extraordinary ray E are respectively rotated by 45 ° counterclockwise, and the optical signal A propagates in the opposite direction (not shown). In this case, the polarization directions of the ordinary ray O and the extraordinary ray E are respectively rotated by 45 ° in the clockwise direction.

  The converging rod lens 8 is composed of a gradient index rod lens having a phase difference of about π / 2. When the ordinary ray O and the extraordinary ray E propagate in the forward direction, these rays O and E are parallel rays. When the light is condensed near the focusing center optical axis 8c on the lens end face 8b side and propagates in the opposite direction, the light beams O and E are moved away from the focusing center optical axis 8c and on the lens end face 8a side. Convert to parallel rays. A spacer 9 made of a glass plate having a concave cross section is fixed to the lens end surface 8 b of the converging rod lens 8. A magnetized garnet crystal plate 10 made of a Faraday element is disposed and fixed in the recess of the spacer 9. The magnetized garnet crystal plate 10 is pre-magnetized and rotates the polarization directions of the ordinary ray O and the extraordinary ray E non-reciprocally regardless of the propagation direction and always by a constant counterclockwise direction by 22.5 °. .

  A reflecting mirror 11 is fixed to the spacer 9 at the other end of the reflective optical isolator 2 that covers the concave portion of the spacer 9. The reflecting mirror 11 reflects 95 [%] of the intensity of the optical signal A incident from one end 15a as reflected light R toward the other end 16a, and transmits 5 [%] of the intensity of the incident optical signal A to the transmitted light T. The half mirror 11b which permeate | transmits is provided in the glass plate 11a, and comprises the reflection means. In the present embodiment, the glass plate 11a has an optical axis of the input / output optical fiber 15 through which the optical signal A incident from one end 15a propagates and an input / output light through which the optical signal (reflected light R) emitted to the other end 16a propagates. A cross-section perpendicular to the plane including the optical axis of the fiber 16 and parallel to the traveling direction of the optical signal A incident from one end 15a is formed in a wedge shape. The half mirror 11b is provided on the end face as a reflecting member. The reflecting surface of the half mirror 11 b is formed to be inclined by about 1 ° with respect to a surface perpendicular to the focusing center optical axis 8 c of the focusing rod lens 8.

  As shown in FIG. 1, the light receiving element 3 constituting the optical active element is arranged on the light transmission side of the reflecting mirror 11 so that the light receiving surface 3 a is substantially parallel to the end face of the reflecting mirror 11. The light receiving element 3 is composed of a PIN photodiode with high sensitivity and a fast response speed, and a hemispherical lens 13 is provided on the light receiving surface 3a. The hemispherical lens 13 converts the condensing state of transmitted light T transmitted through the reflecting mirror 11 or light emitted from the light receiving element 3 to the reflecting mirror 11 provided on the side of the reflecting mirror 11 facing the half mirror 11b. Condensing means is configured.

  The reflective optical isolator 2 is housed and fixed inside a cylindrical optical isolator housing 22 with its periphery held by the optical isolator holder 21. An end cap 23 is attached to the left end opening of the optical isolator housing 22 to close the left end opening. In the vicinity of the center of the end cap 23, a hole through which the input / output optical fibers 15 and 16 pass is formed. The optical isolator section holding section 21, the optical isolator section casing 22 and the end cap 23 are all made of stainless steel. The reflective optical isolator 2 includes the optical isolator section holding section 21, the optical isolator section casing 22 and the end cap 23. It is held and fixed by an isolator casing 20 comprising a cap 23. On the other hand, a light receiving element housing 30 made of stainless steel is attached to the right end opening of the optical isolator housing 22, and the right end opening is closed. The light receiving element housing 30 has a hole into which the light receiving element 3 is inserted. The light receiving element 3 is held and fixed to the light receiving element housing 30 in a state of being inserted into the hole. At this time, the position of the light receiving element 3 is adjusted so that the optical axis of the transmitted light T transmitted through the reflecting mirror 11 and the optical axis of the hemispherical lens 13 coincide with each other.

  The inline-type hybrid optical device 1 includes a reflective optical isolator 2 and a light receiving element 3, the optical axis of the reflected light R reflected by the reflective mirror 11 or the optical axis of the transmitted light T transmitted through the reflective mirror 11, and a hemispherical lens. 13 is configured to be fixed to each other via the isolator housing 20 and the light receiving device housing 30 so that the optical axes of the light receiving devices 3 through 13 are coincident or substantially coincide with each other and are optically coupled by collimated light. ing.

  The operation when the optical signal A having a wavelength of 1.55 [μm] is incident on the in-line hybrid optical device 1 in the above configuration will be described with reference to FIG.

  FIGS. 7A to 7I show the normal state of the optical signal A propagating in the forward direction at the positions FA, FB, FC, FD, FE, FF, FG, FH, and FJ indicated by arrows in FIG. The polarization state and arrangement relationship of the light beam O and the extraordinary light beam E are shown. The polarization state and the arrangement relationship are shown in FIG. 2 in a state where the rutile plate 5 side is viewed from the two-core ferrule 4 side, and the direction perpendicular to the paper surface is the respective of the input / output optical fibers 15 and 16. It is in the optical axis direction. In FIG. 3, the dotted line drawn horizontally represents a plane including the optical axes of the input / output optical fibers 15, 16, and the alternate long and short dashed line represents the center between the optical axes of the input / output optical fibers 15, 16. As shown, a plane perpendicular to the plane including the optical axes of the input and output optical fibers 15 and 16 is shown.

  An optical signal A having a wavelength of 1.55 [μm] incident in the forward direction from one end 15 a of the input / output optical fiber 15 is first incident on the rutile plate 5 at a predetermined angle. FIG. 3A shows the arrangement relationship of the optical signal A at this time, and it is considered that the optical signal A is composed of two independent polarization components of an ordinary ray O and an extraordinary ray E that are orthogonal to each other. Can do. As described above, the crystal optical axis 5 c of the rutile plate 5 is oriented in a direction perpendicular to the plane including the optical axes of the input / output optical fibers 15 and 16. For this reason, when the optical signal A passes through the rutile plate 5, the extraordinary ray E receives the spatial displacement 5d from the ordinary ray O, and as shown in FIG. The ordinary ray O and the extraordinary ray E are spatially separated in a direction perpendicular to the plane including the optical axis.

  The separated ordinary ray O and extraordinary ray E are incident on the half-wave plate 7 at a predetermined angle. The optical axis of the half-wave plate 7 is oriented at an angle of 22.5 ° counterclockwise with respect to the polarization direction of the ordinary ray O in the state shown in FIG. The polarization direction of the light beam E is rotated by 45 degrees counterclockwise as shown in FIG.

  Subsequently, the ordinary ray O and the extraordinary ray E are incident on the converging rod lens 8. At that time, the ordinary ray O and the extraordinary ray E are parallel to the plane including the optical axis of each of the input / output optical fibers 15 and 16 and the plane including the converging center optical axis 8c of the converging rod lens 8 is referred to as the ordinary ray O. The extraordinary ray E is incident at a position sandwiched between the upper and lower sides at substantially equal intervals (see FIG. 2B). At this time, the ordinary ray O and the extraordinary ray E are substantially equidistant from the focusing center optical axis 8c. In the converging rod lens 8, the ordinary ray O and the extraordinary ray E are converted into collimated light, approaching each other as they travel, approaching the converging center optical axis 8c, and exiting from the lens end face 8b. The state of the ordinary ray O and the extraordinary ray E at this time is shown in FIG.

  The ordinary ray O and the extraordinary ray E emitted from the lens end surface 8 b of the converging rod lens 8 then pass through the spacer 9 and enter the magnetized garnet crystal plate 10. The polarization directions of the ordinary ray O and the extraordinary ray E are rotated by 22.5 ° counterclockwise by the magnetized garnet crystal plate 10, respectively. Next, the optical signal A from the magnetized garnet crystal plate 10 is reflected by the half mirror 11b of the reflecting mirror 11 to become reflected light R, and part of it becomes transmitted light T. The positions of O and extraordinary ray E substantially coincide as shown in FIG. The transmitted light T propagates as collimated light and enters the light receiving surface 3 a of the light receiving element 3 through the hemispherical lens 13. As a result, the optical signal A incident in the forward direction from the input / output optical fiber 15 is constantly observed based on the transmitted light T detected by the light receiving element 3.

  On the other hand, the ordinary ray O and extraordinary ray E of the reflected light R reflected by the reflecting mirror 11 are incident on the magnetized garnet crystal plate 10 again, and are further rotated by 22.5 ° counterclockwise by the magnetized garnet crystal plate 10, respectively. Is done. Each light beam O, E passes back and forth through the magnetized garnet crystal plate 10 so that the polarization direction is rotated 45 ° counterclockwise, and the half-wave plate 7 rotates 45 °. As a result, each of them is rotated 90 ° counterclockwise. This state is shown in FIG.

  Next, the ordinary ray O and the extraordinary ray E emitted from the magnetized garnet crystal plate 10 pass through the spacer 9 and enter the converging rod lens 8. Although the physical positions of the ordinary ray O and the extraordinary ray E are interchanged with respect to the converging center optical axis 8c of the converging rod lens 8 due to the reflection by the reflecting mirror 11, each polarization state is the same as before the reflection. keeping.

  Even after passing through the magnetized garnet crystal plate 10, the ordinary ray O and extraordinary ray E are separated from each other as they travel and away from the focusing center optical axis 8 c, but after passing through the converging rod lens 8, they converge. Due to the effect of the characteristic rod lens 8, it is converted into a condensed light beam and becomes a substantially parallel light beam. The state at this time is shown in FIG. Subsequently, the ordinary ray O and the extraordinary ray E pass through the quartz glass plate 6, but the polarization direction of each ray is not affected. The state at this time is shown in FIG.

  Next, the ordinary ray O and the extraordinary ray E are incident on the rutile plate 5 at a predetermined angle. In the rutile plate 5, the ordinary light O is rotated by 90 ° and is polarized in a direction parallel to the crystal optical axis 5 c of the rutile plate 5. Affected. However, the extraordinary ray E is rotated by 90 ° and has a polarization in a direction perpendicular to the crystal optical axis 5c of the rutile plate 5, so that it does not receive a spatial displacement action as ordinary light. pass. Accordingly, the ordinary ray O that has undergone spatial displacement has the same optical axis as that of the extraordinary ray E and enters the input / output optical fiber 16 as the incident light signal A, as shown in FIG. The light is transmitted as a forward output optical signal from one end 16a of the input / output optical fiber 16 to an external optical signal path.

  Similarly, when the optical signal A is incident in the opposite direction from the one end 16 a of the input / output optical fiber 16, the optical signal A separated into the ordinary ray O and the extraordinary ray E is transmitted to the half mirror 11 b of the reflecting mirror 11. The intensity component of about 95 [%] of the optical signal A is reflected as the reflected light R, and the intensity component of about 5 [%] is transmitted as the transmitted light T. The transmitted light T propagates as collimated light and enters the light receiving surface 3 a of the light receiving element 3 via the hemispherical lens 13. On the other hand, the ordinary ray O and extraordinary ray E of the reflected light R reflected by the reflecting mirror 11 are polarized at an angle of −45 ° in the polarization direction rotated by the half-wave plate 7 and rotated by the magnetized garnet crystal plate 10. The angle of 45 ° in the wave direction cancels out, and the total rotation angle in the polarization direction of the ordinary ray O and the extraordinary ray E becomes 0 °. It does not coincide with the optical axis of the output optical fiber 15. Accordingly, the optical signal A incident in the reverse direction from the input / output optical fiber 16 is transmitted to the transmitted light T detected by the light receiving element 3 as in the case where the optical signal A is incident in the forward direction from the input / output optical fiber 15. However, since the reflected light R is isolated as described above, it is not transmitted as an output optical signal in the opposite direction from the one end 15a of the input / output optical fiber 15 to the external optical signal path. .

  According to the in-line type hybrid optical device 1 according to the present embodiment, as described above, the optical axis of the reflected light R reflected by the reflecting mirror 11 or the optical axis of the transmitted light T transmitted through the reflecting mirror 11 and the light receiving element. When the optical axis of 3 coincides with or substantially coincides with the optical axis, the reflective optical isolator 2 and the light receiving element 3 are optically coupled by collimated light. For this reason, the mode field of the transmitted light T that is transmitted through the reflecting mirror 11 and incident on the light receiving surface 3a of the light receiving element 3 from the reflective optical isolator 2 through the hemispherical lens 13 becomes substantially parallel light, and the mode field diameter. Will be big. As a result, the tolerance of the relative alignment error in the three axis (XYZ axis) directions between the reflective optical isolator 2 and the light receiving element 3 is improved. Accordingly, the angle of the optical axis of the light receiving element 3 with respect to the reflecting mirror 11 is accurately adjusted, and the reflective optical isolator 2 and the light receiving element 3 are simply fixed to each other via the isolator casing 20 and the light receiving element casing 30. Thus, the optical coupling between the reflective optical isolator 2 and the light receiving element 3 can be performed reliably and easily, and the monitor PD as in the prior art disclosed in Non-Patent Document 1 and Patent Document 3 can be used. The second rod lens for use or the fourth rod lens for the light receiving element is integrated with the optical isolator in advance, and the optical isolator unit integrated with the second rod lens or the fourth rod lens and these There is no need to align the monitor PD or the light receiving element, which is not provided with the rod lens, with the optical coupling system. As a result, the in-line hybrid optical device 1 is provided in which the package structure is relatively simplified, the optical characteristics are stable, and the manufacturing cost can be suppressed.

  In the present embodiment, the reflecting mirror 11 includes the half mirror 11 b that transmits the intensity of the optical signal incident from the input / output optical fibers 15 and 16, and the optical active element includes the light receiving element 3. The area of the light receiving surface 3a can be increased, and the angle alignment of the optical axis of the light receiving element 3 with respect to the reflecting mirror 11 has a relatively large tolerance for relative alignment errors compared to other optical active elements. For this reason, the relative alignment between the reflective optical isolator 2 and the light receiving element 3 can be more reliably and easily performed as compared to other optical active elements.

  In the present embodiment, the half mirror 11b is provided on the end surface of the glass plate 11a inclined with respect to the traveling direction of the optical signal A incident from the one end 15a of the input / output optical fiber 15. Therefore, the half mirror 11b. Thus, it is possible to prevent the multiple reflected light from affecting the optical characteristics in the reflective optical isolator 2.

  In the above embodiment, the case where the hemispherical lens 13 is used as the light collecting means provided on the light receiving surface 3a of the light receiving element 3 has been described. However, the reflective optical isolator 2 and the light receiving element 3 are optically coupled by collimated light. If it is the structure to be used, the lens used for the condensing means of the light receiving element 3 can be changed suitably. For example, instead of the hemispherical lens 13, other spherical lenses, various lenses such as an aspherical lens or a fused lens can be used as the light collecting means of the light receiving element 3.

  In the above embodiment, a PIN photodiode is used as the light receiving element 3, but the element used as the light receiving element 3 can be changed as appropriate.

  Moreover, in the said embodiment, the reflective mirror 11 consists of the glass plate 11a in which the cross section was formed in the wedge shape, and the reflectance and transmittance | permeability in the half mirror 11b are respectively about 95 [%] and about 5 [%]. Although the case where it is set has been described, the present invention is not limited to this. The cross-sectional shape of the reflecting mirror 11, its optical material, the material of the reflecting member, and the like can be changed as appropriate. In this way, by changing the characteristics of the reflecting means, it is possible to appropriately adjust the reflectance, transmittance, the effect of preventing multiple reflection, and the like.

  In the above embodiment, the case where the reflecting mirror 11 including the half mirror 11b that transmits the intensity of the incident optical signal is used as the reflecting unit and the light receiving element 3 is used as the optical active element has been described. The invention is not limited to this. The reflection means is composed of a wavelength selection filter that transmits an optical signal in a specific wavelength region, and the optical active element is composed of at least one element among the light receiving element or the light emitting element, and is opposed to the wavelength selection filter. It is also possible to provide a condensing means for converting the condensing state of the light transmitted through the wavelength selection filter or the light emitted from the optical active element to the reflecting means.

  Also in this configuration, the light that passes through the wavelength selection filter and is emitted from the reflective optical isolator 2 to the optical active element, or the light that is emitted from the optical active element to the reflective optical isolator 2 propagates as collimated light. Since the reflective optical isolator 2 and the optical active element are optically coupled by the collimated light via the light collecting means, the relative alignment between the reflective optical isolator 2 and the optical active element is performed as in the above embodiment. It is possible to provide an in-line hybrid optical device that can be easily performed, reduced manufacturing costs, and has stable optical characteristics.

  Further, according to this configuration, the reflection type optical isolator 2 is optically coupled with an optical active element constituted by an element such as a light receiving element or a light emitting element, and the optical active element has various optical signals in a specific wavelength region. With this function, it is possible to add value to the optical signal isolated by the reflective optical isolator 2 or to use a part of the isolated optical signal.

  For example, an optical signal in the vicinity of a wavelength of 1480 [nm], for example, an optical signal in a wavelength region of 1480 ± 10 to 20 [nm] is transmitted, and the optical signal A having a wavelength of 1.55 [μm] in the above embodiment is used. The in-line type hybrid optical device is an optical fiber amplifier by using a wavelength selection filter that reflects an optical signal longer than this as a reflection means and using a light emitting element such as a pumping semiconductor laser light source as an optical active element. It functions as a device for use. In this case, the mode field of the light emitted from the pumping semiconductor laser light source and emitted to the reflective optical isolator 2 together with the reflected light R reflected by the reflecting means becomes substantially parallel light, and the mode field diameter becomes large. . As a result, it is possible to realize a hybrid optical device that is easy in relative alignment during the assembly operation between the reflective optical isolator 2 and the pumping semiconductor laser, has low manufacturing costs, and has stable optical characteristics.

It is a partially broken side view which shows the internal structure of the in-line type | mold hybrid optical device by one Embodiment of this invention. FIG. 2 shows a schematic configuration of the reflective optical isolator shown in FIG. 1, (a) is a plan view thereof, and (b) is a side view thereof. FIG. 3 is a state relationship diagram showing polarization states and arrangement relationships of ordinary rays and extraordinary rays at each position in the reflective optical isolator shown in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... In-line type hybrid optical device 2 ... Reflection type optical isolator 3 ... Light receiving element 3a ... Light receiving surface 4 ... Two-core ferrule 5 ... Rutile plate 5c ... Crystal optical axis 5d ... Spatial displacement 6 ... Quartz glass plate 7 ... Half wave plate 8 ... Converging rod lens 8c ... Converging center optical axis 9 ... Spacer 10 ... Magnetized garnet crystal plate 11 ... Reflecting mirror 11a ... Glass plate 11b ... Half mirror 13 ... Hemispherical lens 15, 16 ... Input / output optical fiber 20 ... Isolator housing Body 21: Optical isolator holding unit 22 ... Optical isolator housing 23 ... End cap 30 ... Light receiving element housing A ... Optical signal E ... Abnormal light O ... Normal light R ... Reflected light T ... Transmitted light

Claims (6)

An inline type having an optical signal input terminal and an output terminal at one end and reflecting means for reflecting an optical signal incident from the input terminal to the output terminal side and transmitting a part of the incident optical signal at the other end A reflective optical isolator portion of
An optical active element disposed on the light transmitting side of the reflecting means;
An in-line hybrid optical device configured with
The optical active element includes a condensing unit that converts a condensing state of light transmitted through the reflecting unit or light emitted to the reflecting unit on a side facing the reflecting unit,
The reflection type optical isolator section and the optical active element include an optical axis of light reflected by the reflection means or an optical axis of light transmitted through the reflection means, and an optical axis of the optical active element via the condensing means. Are matched or substantially matched, and the reflective optical isolator section and the optical active element are fixed to each other so as to be optically coupled by collimated light.   The in-line type hybrid optical device according to claim 1, wherein the condensing means comprises any one of a spherical lens, an aspherical lens, and a fused lens. The reflecting means comprises a half mirror that transmits the intensity of the optical signal incident from the input terminal,
The inline hybrid optical device according to claim 1, wherein the optical active element is a light receiving element. The reflecting means comprises a wavelength selection filter that transmits an optical signal in a specific wavelength region,
The inline hybrid optical device according to claim 1, wherein the optical active element includes at least one element among a light receiving element or a light emitting element.   5. The inline type according to claim 4, wherein the wavelength selection filter transmits an optical signal in the vicinity of a wavelength of 1480 nm as an optical signal in the specific wavelength region, and reflects an optical signal on a longer wavelength side. Hybrid optical device.   The reflecting means is orthogonal to a plane including the optical axis of the optical signal incident from the input terminal and the optical axis of the optical signal output to the output terminal, and is parallel to the traveling direction of the optical signal incident from the input terminal. The optical member having a cross section formed in a wedge shape is provided with a reflecting member that reflects an optical signal and transmits a part thereof on a surface facing the optical active element. The in-line type hybrid optical device according to any one of claims 1 to 5.

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