JP2013148825A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate electrical coupling of all of light receiving elements for realizing wavelength locker even without using a support member expressly meant for a light receiving element.SOLUTION: A first light receiving element (18-1) that is a rear incidence type light receiving element is disposed on a top face of a first beam splitter (16-1), an optical filter (17) is disposed on a top face of a second beam splitter (16-2), and a second light receiving element (18-2) that is a rear incidence type light receiving element is disposed on a top face of the optical filter (17). Here, the first beam splitter (16-1) emits branched light from the top face thereof and the second beam splitter (16-2) emits branched light from the top face thereof.

Description

  The present invention relates to an optical module.

  Some light sources for the transmission side of an optical communication module have a function of changing the wavelength of emitted light and selecting and emitting light of a desired wavelength from a changeable band. Hereinafter, such a light source is referred to as a wavelength tunable optical element. An optical module on the transmission side using a wavelength tunable optical element may use feedback control called a wavelength locker to control the oscillation wavelength from a band that can be changed to a desired wavelength. As an example of a wavelength locker, by comparing the light intensity of light emitted from a light source with the light intensity of light transmitted through an optical filter whose transmittance varies depending on the wavelength of transmitted light, a desired wavelength is compared. There is a configuration in which a deviation from the position is detected and feedback control is performed.

  For example, Patent Document 1 describes an example of a transmission optical module equipped with a wavelength locker. The wavelength locker described in Patent Document 1 uses two optical elements (beam splitters) that branch light partially after collimating light emitted from an optical element serving as a light source using a lens. Thus, the light intensity detection light beam of the emitted light and the light intensity detection light beam transmitted through the optical filter are branched.

  In general, a light receiving element that converts light intensity into electric current is used for light intensity detection, and a support member dedicated to the light receiving element is required for the purpose of ensuring high optical coupling efficiency and the purpose of wiring for electrical coupling. . When a dedicated support member is used, the area required for configuring the wavelength locker and the cost for the support member are increased, which is a problem for downsizing and cost reduction of the optical module on the transmission side.

  In this regard, Patent Document 2 describes an example of a configuration in which a light receiving element detects the light intensity of a light source and the transmitted light intensity of an optical filter without using a dedicated support member. In the configuration described in Patent Document 2 (for example, FIG. 1), a light beam is branched into two by a cubic beam splitter, and only a light receiving element is directly joined to a surface from which one branched light is emitted, and the other branch. In this configuration, an optical filter and a light receiving element are connected and directly joined to a surface from which light is emitted.

JP 2011-124444 A JP 2002-299745 A

  In order to configure the wavelength locker, it is necessary to realize not only optical coupling but also electrical coupling. In general, electrical coupling of the optical elements including the light receiving element is arranged such that the electrode portion of the optical element appears above the optical module, and a conductive wire is pressed from above the optical module to connect the wires.

  In the case of Patent Document 2 (for example, FIG. 1), since at least one of the two light receiving elements for realizing the wavelength locker has the electrode portion facing the upper side of the optical module, it relates to both of the light receiving elements. It is difficult to easily perform wire connection.

  An object of the present invention is to make it possible to easily perform all electrical coupling of a light receiving element for realizing a wavelength locker even when a support member dedicated to the light receiving element is not used.

  In order to solve the above problems, an optical module according to the present invention is installed on a platform substrate and emits light, and a wavelength tunable optical element that is installed on the platform substrate and transmits light emitted from the wavelength tunable optical element. A first beam splitter that branches into light and branched light; a first light receiving element that detects the light intensity of the branched light emitted from the first beam splitter; and A second beam splitter for branching the transmitted light emitted from the beam splitter into a transmitted light and a branched light; an optical filter through which the branched light emitted from the second beam splitter passes; and the optical filter And a second light receiving element for detecting the light intensity of the light, and the first light receiving element and the second light receiving element are back-illuminated light receiving elements, The first light receiving element is installed on a surface of one of the first beam splitter and the second beam splitter opposite to the surface in contact with the platform substrate. The optical filter is disposed on a surface of the other of the first beam splitter and the second beam splitter that is opposite to the surface in contact with the platform substrate, The second light receiving element is installed on the surface of the optical filter opposite to the surface in contact with the other beam splitter, and the first beam splitter is connected to the first beam splitter. Branching light is emitted from a surface of the surface opposite to the surface in contact with the platform substrate, and the second beam splitter includes the second beam splitter. Of the faces, to the surface in contact with the platform substrate, characterized in that emits branched light from the opposite side. The first light receiving element may be wired for electrical coupling on a surface opposite to the surface in contact with the first beam splitter or the second beam splitter, The light receiving element may be wired for electrical coupling on a surface opposite to the surface in contact with the optical filter.

  The optical module may output transmitted light emitted from the second beam splitter. The optical module may further include a modulation element that modulates the transmitted light emitted from the second beam splitter, and may output light modulated by the modulation element.

  According to the present invention, even when a support member dedicated to a light receiving element is not used, the entire electrical coupling of the light receiving elements for realizing the wavelength locker can be easily performed.

It is a figure which shows a mode that the inside of the optical module which concerns on one Embodiment of this invention was seen from upper direction. It is a figure which shows a mode that the inside of the optical module which concerns on one Embodiment of this invention was seen from the side surface. It is a figure which shows a mode that the inside of the optical module in a modification was seen from upper direction. It is a figure which shows a mode that the inside of the optical module in a modification was seen from the side surface.

  1A and 1B are diagrams illustrating an example of the configuration of the optical module 1 according to the present embodiment. FIG. 1A shows a state in which the inside of the optical module 1 is viewed from above the optical module 1. FIG. 1B shows a state in which the inside of the optical module 1 is viewed from the side surface of the optical module 1.

  The optical module 1 according to this embodiment includes, for example, a thermoelectric cooler (hereinafter referred to as TEC) 11, a platform substrate 12, a wavelength tunable optical element 13 that is a light source, a first lens 14, and a second lens in a housing 10. Lens 15, first beam splitter 16-1, second beam splitter 16-2, optical filter 17 (etalon filter), first light receiving element 18-1, and second light receiving element 18-2, Is provided.

  As shown in FIG. 1B, the TEC 11 is disposed on the bottom surface of the housing 10 of the optical module 1. A platform substrate 12 is disposed on the TEC 11. On the platform substrate 12, the variable wavelength optical element 13, the first lens 14, the first beam splitter 16-1, the second beam splitter 16-2, and the second lens 15 are provided. , Is arranged. The wavelength tunable optical element 13, the first lens 14, the first beam splitter 16-1, the second beam splitter 16-2, and the second lens 15 are on the optical axis of the wavelength tunable element 13. Is arranged. Both the first beam splitter 16-1 and the second beam splitter 16-2 have a cube shape in which two right-angle prisms are joined, and incident light is transmitted as transmitted light at the joint surface of the two right-angle prisms. Has the function of branching to branch light.

  The first light receiving element 18-1 is disposed on the upper surface of the first beam splitter 16-1. Therefore, the first light receiving element 18-1 is supported by the first beam splitter 16-1. Here, the first light receiving element 18-1 is a back-illuminated light receiving element, and is arranged so that the light receiving surface 23 is bonded to the upper surface of the first beam splitter 16-1. Therefore, the two electrodes 24-1 (anode and cathode) of the first light receiving element 18-1 face upward. Therefore, wire connection using the conductive wire 21 with an external feedback control device (not shown), that is, electrical coupling can be easily performed. Note that, for joining the upper surface of the first beam splitter 16-1 and the light receiving surface 23, a joining material whose refractive index is adjusted so as to transmit light and suppress reflection generated at the joining portion is used.

  An optical filter 17 is disposed on the upper surface of the second beam splitter 16-2, and a second light receiving element 18-2 is disposed on the upper surface of the optical filter 17. Therefore, the second light receiving element 18-2 is supported by the second beam splitter 16-2 and the optical filter 17. Here, the second light receiving element 18-2 is also a back-illuminated light receiving element, and is arranged so that the light receiving surface 22 is bonded to the upper surface of the optical filter 17. Therefore, the two electrodes 24-2 (anode and cathode) of the second light receiving element 18-2 face upward, and electrical coupling can be easily performed with respect to the second light receiving element 18-2. Yes. In addition, the upper surface of the second beam splitter 16-2 and the optical filter 17 and the upper surface of the optical filter 17 and the light receiving surface 22 are bonded to each other between the upper surface of the first beam splitter 16-1 and the light receiving surface 23. Similar to the bonding, a bonding material whose refractive index is adjusted so as to transmit light and suppress reflection generated at the bonding portion is used.

  Note that the upper surface of the first beam splitter 16-1 is a surface opposite to the bottom surface of the first beam splitter 16-1 (that is, the surface bonded to the platform substrate 12), and the second beam splitter 16-1. The upper surface of the splitter 16-2 is a surface opposite to the bottom surface of the second beam splitter 16-2 (that is, the surface bonded to the platform substrate 12). The upper surface of the optical filter 17 is a surface opposite to the bottom surface of the optical filter 17 (that is, the surface bonded to the upper surface of the second beam splitter 16-2).

  Hereinafter, the operation of the optical module 1 will be described. In the optical module 1 according to the present embodiment, the light output from the wavelength tunable optical element 13 passes through the first lens 14 and becomes parallel light, and is incident on the first beam splitter 16-1. Then, the first beam splitter 16-1 branches the incident light into transmitted light and branched light, emits the transmitted light to the second beam splitter 16-2, and transmits the branched light to the second light splitter 16-2. The light is emitted from the upper surface to the first light receiving element 18-1. That is, the first beam splitter 16-1 emits the transmitted light in the optical axis direction and emits the branched light in a direction perpendicular to the optical axis. The branched light is incident on the first light receiving element 18-1. The light intensity of the branched light is detected by the first light receiving element 18-1, and the detected light intensity is electrically sent to the feedback control device via the conductive wire 21.

  The transmitted light emitted from the first beam splitter 16-1 is incident on the second beam splitter 16-2. The second beam splitter 16-2 splits the incident light into transmitted light and branched light, emits the transmitted light to the optical fiber 19, and outputs the branched light to the optical filter 17 from its upper surface. That is, the second beam splitter 16-2 emits the transmitted light in the optical axis direction and emits the branched light in a direction perpendicular to the optical axis. The transmitted light is incident on the second lens 15. The transmitted light is converged by the second lens 15 and incident on the optical fiber 19. The light coupled and incident on the optical fiber 19 is output from the optical fiber 19 to the outside.

  The light emitted from the upper surface of the second beam splitter 16-2 is incident on the optical filter 17. The light emitted from the upper surface of the second beam splitter 16-2 passes through the optical filter 17 and then enters the second light receiving element 18-2. In the second light receiving element 18-2, the received light is transmitted through the optical filter 17, so that the light intensity depending on the wavelength of the light emitted from the wavelength variable optical element 13 is detected. The detected light intensity is electrically sent to the feedback control device via the conductive wire 21.

  As described above, the light intensities detected by the first light receiving element 16-1 and the second light receiving element 16-2 are electrically sent to the feedback control device. Then, the feedback control device feedback-controls the wavelength tunable optical element 13 so that a specific wavelength is output based on the light intensity transmitted electrically. That is, a wavelength locker is realized.

  As described above, in the optical module 1, the first light receiving element 18-1 is supported by the first beam splitter 16-1, and the second light receiving element 18-2 includes the second beam splitter 16-2 and the second beam splitter 16-2. Supported by an optical filter 17. Therefore, the first light receiving element 18-1 and the second light receiving element 18-2 are supported without using a dedicated support member. In addition, the first light receiving element 18-1 which is a back-illuminated light receiving element is arranged so that the light receiving surface 23 is bonded to the upper surface of the first beam splitter 16-1, and the back-illuminated light receiving element is used. Since a certain second light receiving element 18-2 is disposed such that its light receiving surface 22 is bonded to the upper surface of the optical filter 17 disposed on the upper surface of the second beam splitter 16-2, the first light receiving element 18-2 is provided. Both the element 18-1 and the second light receiving element 18-2 can be easily electrically coupled.

  In addition, this invention is not limited to the said embodiment.

  For example, in the above embodiment, the configuration using the front output of the wavelength tunable optical element is illustrated, but the rear output may be used.

  Further, for example, an isolator is additionally arranged between the first lens 14 and the first beam splitter 16-1 in order to avoid that the reflected light returns to the wavelength tunable optical element 13 and the oscillation state becomes unstable. May be.

  In addition, for example, in order to avoid that reflected light returns to the wavelength tunable optical element 13 and the oscillation state becomes unstable, at least one of the first beam splitter 16-1 and the second beam splitter 16-2. It may be mounted at an angle.

  Further, for example, the first beam splitter 16-1 and the second beam splitter 16-2 may be connected without a gap. Further, for example, the wire connection may be performed by arranging a conductive thin film on the platform substrate and relaying the conductive thin film.

  Further, for example, the first light receiving element 16-1 is disposed on the upper surface of the second beam splitter 16-2, and the optical filter 17 is disposed on the upper surface of the first beam splitter 16-1, and the second light receiving element. The element 18-2 may be disposed on the upper surface of the optical filter 17.

  For example, the optical module 1 may include an element that modulates transmitted light emitted from the second beam splitter 16-2. Hereinafter, this aspect (hereinafter referred to as a modified example) will be described.

  FIG. 2A shows a state in which the inside of the optical module 1 in the modified example is viewed from above, and FIG. 2B shows a state in which the inside is viewed from the side.

  In the modification, the optical module 1 further includes a thermoelectric cooler 11-1 (TEC11-1), a platform substrate 12-1, a third lens 25, and an optical modulator 26 disposed on the TEC11-1. Provided. Of the elements disposed on the platform substrate 12 in the above embodiment, only the second lens 15 is disposed on the platform substrate 12-1. In addition to the second lens 15, an optical modulator 26 and a third lens 25 are disposed on the platform substrate 12-1.

  In the modified example, the transmitted light emitted from the second beam splitter 16-2 is incident on the second lens 15, converged, and coupled and incident on the optical modulator 26. The light modulator 26 performs processing such as light modulation and amplification on the incident light. The processed light is coupled and incident on the optical fiber 19 via the third lens 25 and is output to the outside from the optical fiber 19.

  DESCRIPTION OF SYMBOLS 1 Optical module, 10 Housing | casing, 11, 11-1 Heat transfer cooler (TEC), 12, 12-1 Platform substrate, 13 Wavelength variable optical element, 14 1st lens, 15 2nd lens, 16-1 1st 1 beam splitter, 16-2 second beam splitter, 17 optical filter, 18-1 first light receiving element, 18-2 second light receiving element, 19 optical fiber, 21 conductive wire, 22, 23 light receiving surface , 24-1, 24-2 electrodes, 25 third lens, 26 light modulator.

Claims (4)

A tunable optical element installed on the platform substrate and emitting light;
A first beam splitter installed on the platform substrate and for branching light emitted from the wavelength tunable optical element into transmitted light and branched light;
A first light receiving element for detecting the light intensity of the branched light emitted from the first beam splitter;
A second beam splitter installed on the platform substrate and branching the transmitted light emitted from the first beam splitter into a transmitted light and a branched light;
An optical filter through which the branched light emitted from the second beam splitter passes;
A second light receiving element for detecting the light intensity of the light that has passed through the optical filter;
With
The first light receiving element and the second light receiving element are back-illuminated light receiving elements,
The first light receiving element is installed on a surface of one of the first beam splitter and the second beam splitter opposite to the surface in contact with the platform substrate. ,
The optical filter is disposed on a surface of the other beam splitter of the first beam splitter and the second beam splitter that is opposite to the surface in contact with the platform substrate,
The second light receiving element is installed on the surface of the optical filter opposite to the surface in contact with the other beam splitter,
The first beam splitter emits branched light from the surface of the first beam splitter opposite to the surface in contact with the platform substrate,
The second beam splitter emits branched light from a surface of the second beam splitter opposite to a surface in contact with the platform substrate;
An optical module characterized by The optical module according to claim 1,
Outputting the transmitted light emitted from the second beam splitter;
An optical module characterized by The optical module according to claim 1,
A modulation element that modulates transmitted light emitted from the second beam splitter;
Outputting light modulated by the modulation element;
An optical module characterized by The optical module according to claim 1,
The first light receiving element is wired for electrical coupling on a surface opposite to the surface in contact with the first beam splitter or the second beam splitter,
The second light receiving element has a wiring for electrical coupling on a surface opposite to a surface in contact with the optical filter,
An optical module characterized by

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