JP2004047738A - Optical transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmitter which is strong with respect to the mechanical strain of a housing, and which contains the small number of components at a low cost. <P>SOLUTION: In the optical transmitter including a light-emitting element 53, a Peltier element 55 for radiating heat generated from the element 53 to the housing, a first lens system 61 for converting the output light of the element 53 into a collimated beam, and a second lens system 63 for condensing collimated light to an optical fiber, the element 55 includes a through-hole opened on an optical axis for passing the output light from the element 53 and is connected to a front surface plate of a side for connecting an optical connector of the housing 40. The element 53 and the lens system 61 are fixed on the optical axis at a substrate 54 fixed to the element 55. The lens system 63 is fixed to the optical axis facing the lens system 61 via a housing fixed to the front surface plate. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical transmitter, and more particularly, to an optical transmitter having a Peltier element for dissipating heat generated from a light emitting element to a housing.
[0002]
[Prior art]
The optical transmitter includes a light emitting element and a driving circuit for driving the light emitting element. The drive circuit amplifies an input signal from a device equipped with an optical transmitter, synchronizes the signal with a clock of an optical transmission line, converts the signal into a voltage or current for driving a light emitting element, and outputs the voltage or current.
[0003]
FIG. 1 shows the structure of a conventional optical transmitter. In the optical transmitter, a housing 11 that houses an optical connector for connecting an optical fiber is fixed to a front plate of a housing 10. The bottom plate of the housing 10 is provided with a substrate 22 on which a drive circuit 21 is mounted and a Peltier element 25 on which a substrate 24 on which a light emitting element 23 is mounted is placed and the element temperature of the light emitting element 23 is kept constant. ing. The output light of the light emitting element 23 passes through the first lens system 31 that converts the light into collimated light, passes through the sapphire window 32, and is sent to the housing 11. The housing 11 is provided with a second lens system 33 that focuses collimated light on an optical fiber.
[0004]
The optical transmitter hermetically seals the entire housing 10 so that the light emitting element 23 emits light stably regardless of environmental conditions. The Peltier element 25 absorbs heat generated from the light emitting element and radiates heat to the outside via the bottom plate of the housing 10.
[0005]
FIG. 2 shows the structure of a conventional optical transmitter. A housing 10 of the optical transmitter shown in FIG. 1 includes an optical module 12 and a substrate 22 on which a drive circuit 21 is mounted. The entire optical module 12 is hermetically sealed, and heat generated by the Peltier element 25 is radiated to the outside via the optical module 12 and the bottom plate of the housing 10.
[0006]
[Problems to be solved by the invention]
In the conventional optical transmitter, in order to radiate heat from the bottom plate of the housing 10, the optical transmitter is screwed to the housing of the device on which the optical transmitter is mounted, or screwed to the radiator. At this time, the bottom plate of the casing 10 is distorted, and the optical axis of the light emitting element 23 mounted on the bottom plate via the Peltier element 25 and the substrate 24 is shifted in angle. Such an angle shift results in an angle shift of the optical system including the first lens system 31 and the second lens system 33, and there is a problem that the power incident on the optical fiber decreases.
[0007]
Further, the conventional optical transmitter requires hermetic sealing with the housing 10 or the optical module 12, and has a problem of high cost. The cost can be reduced by using a metal can type or coaxial type package which incorporates a light emitting element and is hermetically sealed. However, in order to fix these packages, a support having a special shape having good heat conductivity is required as the substrate 24, and there is a problem that the size of the optical transmitter becomes large.
[0008]
The present invention has been made in view of such a problem, and an object of the present invention is to provide an optical transmitter which is resistant to mechanical distortion of a housing, has a small number of parts, and is low in cost.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an optical transmitter having a light emitting element and a Peltier element for radiating heat generated from the light emitting element to a housing. In the Peltier element, a through hole is formed on an optical axis through which output light of the light emitting element passes, and the Peltier element is fixed to a front plate on a side of the housing to which an optical connector is connected, and the light emitting element is It is characterized by being fixed on the optical axis via a substrate fixed to the element.
[0010]
The invention according to claim 2 is an optical transmitter including: an optical module that converts output light of a light emitting element into collimated light and outputs the collimated light; and a Peltier element for radiating heat generated from the optical module to a housing. In the Peltier element, a through hole is formed on an optical axis through which output light of the light emitting element passes, and the Peltier element is fixed to a front plate on a side of the housing to which an optical connector is connected, and the optical module is a Peltier element , And the light emitting element is fixed on the optical axis.
[0011]
The invention according to claim 3 is characterized in that the optical module according to claim 2 is a metal can type package or a coaxial type package.
[0012]
The invention described in claim 4 is characterized in that the Peltier element according to claim 2 or 3 and the optical module are hermetically sealed.
[0013]
The light emitting element, a Peltier element for dissipating heat generated from the light emitting element to a housing, and a first lens system that converts output light of the light emitting element into collimated light, A second lens system for condensing the collimated light onto an optical fiber, wherein the Peltier element has a through-hole formed on an optical axis through which output light of the light-emitting element passes, and The light emitting element and the first lens system are fixed to the front plate on the side to which an optical connector is connected, and the light emitting element and the first lens system are fixed on the optical axis via a substrate fixed to the Peltier element, and the second lens system is Is fixed on the optical axis in opposition to the first lens system via a housing fixed to the front plate.
[0014]
The invention according to claim 6 is characterized in that the light emitting element according to claim 5 and the first lens system are hermetically sealed and fixed to the Peltier element.
[0015]
The invention according to claim 7 and the peltier element according to claim 6, and the hermetically sealed light emitting element and the first lens system are further hermetically sealed.
[0016]
The invention according to claim 8 is characterized in that the housing according to any one of claims 1 to 7 is a plastic case or a transfer mold.
[0017]
According to a ninth aspect of the present invention, in the optical transmitter according to any one of the first to eighth aspects, a heat pipe for thermally coupling the Peltier element and a bottom plate of the housing is provided. I do.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(1st Embodiment)
FIG. 3 shows the structure of the optical transmitter according to the first embodiment of the present invention. The housing 40 of the optical transmitter includes a front plate to which a housing 41 for housing an optical connector for connecting an optical fiber is fixed, and a bottom plate to which a substrate 52 on which a drive circuit 51 is mounted is fixed. A Peltier element 55 is fixed to a front plate where the housing 40 and the housing 41 are connected. The Peltier element 55 has a through hole on the optical axis through which the output light of the light emitting element 53 passes. A substrate 54 on which the light emitting element 53 is mounted, and a first lens system 61 that converts output light of the light emitting element 53 into collimated light are fixed to a Peltier element 55, and the light emitting element 53 and the first lens system 61 are Each is fixed on the optical axis. The output light of the light emitting element 53 passes through the first lens system 61 and the through hole provided in the Peltier element 55, passes through the sapphire window 62, and is sent to the housing 41. The housing 41 is provided with a second lens system 63 that focuses collimated light on an optical fiber.
[0019]
In the optical transmitter, the entire housing 40 is hermetically sealed so that the light emitting element 53 emits light stably regardless of environmental conditions. The Peltier element absorbs heat generated from the light emitting element and radiates heat to the outside through the front plate of the housing 40. The case uses a plastic case or transfer mold.
[0020]
With such a configuration, since the light emitting element 53 is fixed to the front plate via the Peltier element 55 and the substrate 54 together with the first lens system 61, the light emitting element 53 is separated from the first lens system 61 and the second lens system 63. There is no angle shift in the optical axis of the optical system configured. That is, there is no effect on the mechanical strain of the housing when screwing the optical transmitter to the device on which the optical transmitter is mounted.
[0021]
The optical transmitter shown in FIG. 1 has a structure in which a substrate 24 on which the light emitting element 23 is mounted and a Peltier element 25 are arranged between the optical axis of the light emitting element 23 and the bottom plate. On the other hand, in the optical transmitter shown in FIG. 3, since the distance between the optical axis of the light emitting element 53 and the bottom plate can be set to an arbitrary height in the case design, the height of the optical transmitter can be reduced. .
[0022]
(Second embodiment)
FIG. 4 shows the structure of the optical transmitter according to the first embodiment of the present invention. In the optical transmitter, a housing 41 that houses an optical connector for connecting an optical fiber is fixed to a front plate of a housing 40. An optical module 42 and a substrate 52 on which a drive circuit 51 is mounted are provided on a bottom plate of the housing 40. The Peltier element 55 is fixed to the front plate of the optical module 42. The Peltier element 55 has a through hole on the optical axis through which the output light of the light emitting element 53 passes. A substrate 54 on which the light emitting element 53 is mounted and a first lens system 61 for converting output light of the light emitting element 53 into collimated light are fixed to the Peltier element 55. The output light of the light emitting element 53 passes through the first lens system 61 and the through hole provided in the Peltier element 55, passes through the sapphire window 62, and is sent to the housing 41. The housing 41 is provided with a second lens system 63 that focuses collimated light on an optical fiber. The entire optical module 42 is hermetically sealed, and heat generated by the Peltier element 55 is radiated to the outside via the front plate and the bottom plate of the optical module 42 and the bottom plate of the housing 40.
[0023]
(Third embodiment)
FIG. 5 shows the structure of the optical transmitter according to the third embodiment of the present invention. In the optical transmitter, a housing 41 that houses an optical connector for connecting an optical fiber is fixed to a front plate of a housing 40. A substrate 52 on which the drive circuit 51 is mounted is provided on the bottom plate of the housing 40. A Peltier element 55 is fixed to a front plate where the housing 40 and the housing 41 are connected. In the Peltier element 55, a through hole is formed on the optical axis through which the output light of the light emitting element 53 passes, and the optical module 43 is fixed.
[0024]
FIG. 6 shows the structure of the optical module according to the third embodiment of the present invention. The optical module 43 includes a substrate 54 on which the light emitting element 53 is mounted, and a first lens system 61 that converts output light of the light emitting element 53 into collimated light. The optical module 43 is hermetically sealed in its entirety so that the light emitting element 53 emits light stably regardless of environmental conditions, and a sapphire window 64 is opened on an optical axis through which output light of the light emitting element 53 passes. I have.
[0025]
With such a configuration, since the optical module 43 is hermetically sealed, it is not necessary to hermetically seal the entire housing 40, and the manufacturing cost of the optical transmitter can be reduced. Further, since the light emitting element and a part of the optical system are modularized, the number of components of the optical transmitter can be reduced.
[0026]
FIG. 7 shows a structure of an optical transmitter to which a hermetic seal is added in the third embodiment. The hermetically sealed optical module 43, Peltier element 55, and drive circuit 51 were further hermetically sealed. Since the temperature near the junction between the one end of the Peltier element 55 and the optical module 43 tends to decrease due to low temperature, the reliability of the optical transmitter is improved by adding an airtight seal.
[0027]
(Fourth embodiment)
FIG. 8 shows the structure of the optical transmitter according to the fourth embodiment of the present invention. In the optical transmitter, a housing 41 that houses an optical connector for connecting an optical fiber is fixed to a front plate of a housing 40. A substrate 52 on which the drive circuit 51 is mounted is provided on the bottom plate of the housing 40. A Peltier element 55 is fixed to a front plate where the housing 40 and the housing 41 are connected. In the Peltier element 55, a through hole is formed on the optical axis through which the output light of the light emitting element built in the optical module 44 passes, and the optical module 44 is fixed.
[0028]
The optical module 44 is a metal can or coaxial type package module that incorporates a light emitting element and is hermetically sealed. Since the optical module 44 is directly fixed to the Peltier element 55 fixed to the front plate, the size of the optical transmitter can be reduced, and the number of parts of the optical transmitter can be reduced. In addition, since the optical module 44 is hermetically sealed, it is not necessary to hermetically seal the entire housing 40, so that the manufacturing cost of the optical transmitter can be reduced.
[0029]
FIG. 9 shows a structure of an optical transmitter to which a hermetic seal is added in the fourth embodiment. The hermetically sealed optical module 44 and the Peltier element 55 were further hermetically sealed. The vicinity of the junction between one end of the Peltier element 55 and the optical module 44 is likely to cause dew condensation due to a decrease in temperature. Therefore, the hermetic sealing is added to improve the reliability of the optical transmitter.
[0030]
(Fifth embodiment)
FIG. 10 shows the structure of the optical transmitter according to the fifth embodiment of the present invention. The optical transmitter according to the fourth embodiment is provided with a heat pipe 71 in order to efficiently radiate heat generated from the Peltier element 55. The heat generated by the Peltier element 25 is radiated to the housing or the radiator of the device on which the optical transmitter is mounted via the front plate of the housing 40, the heat pipe 71, and the bottom plate of the housing 40.
[0031]
In each of the above-described embodiments, the Peltier element 55 is fixed to the front plate where the housing 40 and the housing 41 are connected. A plate-shaped or block-shaped fixing plate having a through hole formed on the optical axis through which the output light of the light-emitting element passes is provided between the front plate and the light-emitting element 53, and the Peltier element 55 is fixed to this fixing plate. It is good also as a structure which does.
[0032]
【The invention's effect】
As described above, according to the present invention, a Peltier element having a through-hole formed on the optical axis through which output light of the light-emitting element passes is fixed to the front plate on the side to which the optical connector of the housing is connected, Since the light-emitting element is fixed on the optical axis via the substrate fixed to the Peltier element, it is possible to make the casing resistant to mechanical strain.
[0033]
Further, according to the present invention, since the distance between the optical axis of the light emitting element and the bottom plate can be set to an arbitrary height, the height of the optical transmitter can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a structure of a first example of a conventional optical transmitter.
FIG. 2 is a cross-sectional view illustrating a structure of a second example of the conventional optical transmitter.
FIG. 3 is a sectional view showing a structure of the optical transmitter according to the first embodiment of the present invention.
FIG. 4 is a cross-sectional view illustrating a structure of an optical transmitter according to a second embodiment of the present invention.
FIG. 5 is a cross-sectional view illustrating a structure of an optical transmitter according to a third embodiment of the present invention.
FIG. 6 is a sectional view illustrating a structure of an optical module according to a third embodiment of the present invention.
FIG. 7 is a cross-sectional view illustrating a structure of an optical transmitter to which a hermetic seal is added in the third embodiment.
FIG. 8 is a sectional view showing a structure of an optical transmitter according to a fourth embodiment of the present invention.
FIG. 9 is a cross-sectional view showing a structure of an optical transmitter to which a hermetic seal is added in the fourth embodiment.
FIG. 10 is a sectional view showing a structure of an optical transmitter according to a fifth embodiment of the present invention.
[Explanation of symbols]
10, 40 housing 11, 41 housing 12, 42 to 44 optical module 21, 51 drive circuit 22, 24, 52, 54 substrate 23, 53 light emitting element 25, 55 Peltier element 31, 61 first lens system 32, 62, 64 Sapphire windows 33, 63 Second lens system

Claims (9)

A light-emitting element, and an optical transmitter having a Peltier element for radiating heat generated from the light-emitting element to a housing,
The Peltier element has a through-hole formed on an optical axis through which output light of the light-emitting element passes, and is fixed to a front plate on a side of the housing to which an optical connector is connected,
The optical transmitter, wherein the light emitting element is fixed on the optical axis via a substrate fixed to the Peltier element. An optical module that converts the output light of the light emitting element into a collimated light and outputs the collimated light, and a Peltier element for dissipating heat generated from the optical module to a housing;
The Peltier element has a through-hole formed on an optical axis through which output light of the light-emitting element passes, and is fixed to a front plate on a side of the housing to which an optical connector is connected,
The optical transmitter, wherein the optical module is fixed to the Peltier element, and the light emitting element is fixed on the optical axis. The optical transmitter according to claim 2, wherein the optical module is a metal can type package or a coaxial type package. The optical transmitter according to claim 2, wherein the Peltier element and the optical module are hermetically sealed. A light emitting element, a Peltier element for dissipating heat generated from the light emitting element to a housing, a first lens system for converting output light of the light emitting element into collimated light, and condensing the collimated light on an optical fiber An optical transmitter having a second lens system,
The Peltier element has a through-hole formed on an optical axis through which output light of the light-emitting element passes, and is fixed to a front plate on a side of the housing to which an optical connector is connected,
The light emitting element and the first lens system are fixed on the optical axis via a substrate fixed to the Peltier element,
An optical transmitter, wherein the second lens system is fixed on the optical axis in opposition to the first lens system via a housing fixed to the front plate. The optical transmitter according to claim 5, wherein the light emitting element and the first lens system are hermetically sealed and fixed to the Peltier element. The optical transmitter according to claim 6, wherein the Peltier element, the light-emitting element, and the first lens system that are hermetically sealed are further hermetically sealed. The optical transmitter according to claim 1, wherein the housing is a plastic case or a transfer mold. 9. The optical transmitter according to claim 1, further comprising a heat pipe for thermally coupling the Peltier element and a bottom plate of the housing.

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