JP3153893B2 - High frequency band optical module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency band optical module, and more particularly to a semiconductor light emitting / receiving element, a semiconductor optical modulator and other high-frequency band optical modules.

[0002]

2. Description of the Related Art FIG.
This will be described with reference to FIG. In FIG. 6, reference numeral 1 denotes an optical element. The optical element 1 will be described later in detail. The optical element 1 is electro-mechanically coupled and fixed to a step 31 formed to protrude upward from the stem 3. The stem 3 is a conductor made of a copper tungsten alloy CuW and is grounded. Reference numeral 21 denotes an electric waveguide substrate made of an electric insulating material, and a high-frequency electric waveguide 22 is formed on the surface. The electric waveguide substrate 21 is mechanically coupled and fixed to the stem 3 near the optical element 1. The high-frequency electric waveguide 22 is driven by the high-frequency signal source 2 connected to one end of the high-frequency electric waveguide 22. The other end of the high-frequency signal source 2 is grounded. Reference numeral 24 denotes a terminating resistor connected to the other end of the electric waveguide 22.

Reference numeral 4 denotes a lens constituting an input / output optical device, which is a mechanically strong lens holder 41 made of a metal material.
It is attached to the tip of. Reference numeral 42 denotes an optical fiber for transmitting light. Reference numeral 4 'denotes a lens constituting the same input / output optical device, which is attached to the tip of a mechanically strong lens holder 41' made of a metal material. Reference numeral 42 'denotes an optical fiber for transmitting light. These two lenses are positioned and fixed to face each other with the optical element 1 interposed therebetween.

[0004] The high-frequency band optical module comprises the optical element 1 described above, a pair of light emitting units or light receiving units. The optical element 1 will be described with reference to FIG. FIG. 5 shows a cross section of the optical element 1. Reference numeral 11 denotes an optical waveguide having a minute cross section.
2 and the n-layer 13 are joined. Reference numeral 15 denotes a p-electrode in contact with the p-layer 12, and reference numeral 16 denotes an n-electrode in contact with the n-layer 13. The optical element 1 is electro-mechanically coupled to the step 31 of the stem 3 via the n-electrode 16. The p-electrode 15 of the optical element 1 is connected to a high-frequency electric waveguide 22 formed on the surface of the electric waveguide substrate 21 via a bonding wire 23. Here, the optical element 1
As shown in FIG. 5, the p-electrode 15 is connected to the high-frequency signal source 2 via a bonding wire 23 and an electric waveguide 22.
And the n-electrode 16 is made of a conductor 31 made of a copper-tungsten alloy CuW.
A modulation signal is applied to the optical waveguide 11 from the high-frequency signal source 2 from a place where the optical waveguide 11 is grounded.

The high-frequency band optical module described with reference to FIG. 6 comprises a high-frequency electric waveguide 22, an optical element 1 having a minute optical waveguide 11, an optical fiber 42 and a lens 4.
And an optical device including: In order for the high-frequency band optical module to exhibit high-efficiency optical coupling and high temperature stability, it is necessary to arrange the lens 4 close to the optical element 1. That is, considering the optical coupling between the optical waveguide 11 of the optical element 1 and the lens 4 constituting the input / output optical device,
Since the light emission angle of the optical element 1 is about 30 °, which is considerably large, in order to perform optical coupling between the optical fiber 42 and the optical waveguide 11 with high efficiency, the numerical aperture N
It is necessary to use a lens having a large A. In order to employ the lenses 4 having a large numerical aperture NA and to sufficiently optically couple them to the optical fiber 42, the lens holder 41 holding the lenses 4 must be arranged close to the optical waveguide 11 of the optical element 1. Becomes For example, when a lens 4 having an NA of 0.6 is employed, the distance between the lens 4 and the optical waveguide 11 is 0.3 m.
approach to about m.

The width of the optical waveguide 11 of the optical element 1 is as small as 1 to 2 μm.
If the relative positional accuracy between the lens and the lens 4 does not maintain ± 0.5 μm, the optical coupling efficiency will be degraded. Since it is necessary to secure and maintain the relative position accuracy, the optical waveguide 1 of the lens 4 and the optical element 1
Then, the lens holder 41 is fixed by welding to a case surrounding the entire module (not shown in FIG. 5) and the sleeve of the optical fiber 42 is fixed to the lens holder 41. Fix by welding. That is, these members are made of a metal material having good weldability and high mechanical strength. In addition, as a material constituting these members, a material having the same coefficient of thermal expansion is adopted from the viewpoint of preventing axial displacement due to a temperature change.

[0007]

Referring to FIG. 4B, the high-frequency band optical module described above has an NA of 0.6.
In the case where the lens 4 is adopted, the problem that the optical response characteristic is deteriorated at a specific frequency in a high frequency band exceeding 10 GHz is included, and the working frequency band of the high frequency band optical module is about 10 GHz. It has limited disadvantages. The deterioration of the optical response characteristic is caused by the lens holder 41 made of a metal material being too close to the electric waveguide 22.
As a result of various experimental studies, it has been recognized that the spatial electromagnetic field formed by 2 is disturbed in the vicinity of the lens holder 41.

The present invention has solved the above-mentioned problems of the conventional high-frequency band optical module based on the above recognition.
An object of the present invention is to provide a high-frequency band optical module having an electric waveguide on which an optical element having a minute optical waveguide is mounted.

[0009]

[Means for Solving the Problems]

Claim 1: An optical element 1 having a stem 3 made of a conductive material, having a small optical waveguide 11 and being electro-mechanically coupled and fixed to the stem 3, and having a high-frequency electric waveguide 22 on the surface
Is formed and is provided with an electric waveguide substrate 21 made of an electrically insulating material that is mechanically coupled and fixed to the vicinity of the optical element 1 of the stem 3.
A pair of lens holders 41 and 41 ′ made of a mechanically strong metal material that is positioned and fixed to face each other with the interposed therebetween, and is mechanically coupled and fixed to the lens holders 41 and 41 ′. In the high-frequency band optical module including the optical fibers 42 and 42 ′,
1 is provided with a hollow shield 5 made of a conductive material surrounding the entire optical element 1 which is electromechanically bonded and fixed to the step portion 31 formed on the surface of the optical waveguide 22 and a lens 4. , 4 ′ and the optical element 1 to constitute a high-frequency band optical module in which light passing holes 51 and 51 ′ forming an optical path are formed.

Claim 2: The high-frequency band optical module according to claim 1, further comprising a case 6 surrounding the entire high-frequency band optical module.
The sleeve 42 'and the case 6 are made of a metal material having good weldability and high mechanical strength.
A high-frequency band optical module in which the lens holder 41 is fixed by welding and the sleeve of the optical fiber 42 is fixed to the lens holder 41 by welding.

In another preferred embodiment, the optical device includes a stem made of a conductive material, an optical element having a minute optical waveguide, and being electro-mechanically coupled to and fixed to the stem. An optical waveguide substrate 21 made of an electrically insulating material and having a waveguide 22 formed therein and mechanically coupled and fixed to the optical element 1 of the stem 3 near the optical element 1 is provided. A high-frequency band including a pair of lens holders 41 and 41 ′ positioned and fixed to face each other with the optical fibers 42 and 42 ′ mechanically coupled and fixed to the lens holders 41 and 41 ′. In the optical module, a high-frequency band optical module in which the lens holders 41 and 41 ′ are made of a non-conductive material such as ceramics or glass having high mechanical strength was constructed.

Further, there is provided an optical element 1 having a stem 3 made of a conductive material, having an optical waveguide 11 and being electro-mechanically coupled and fixed to the stem 3, and having a high-frequency The optical waveguide 22 is formed and the optical element 1 of the stem 3 is formed.
An electric waveguide substrate 21 made of an electrically insulating material mechanically coupled and fixed is provided in the vicinity, and lenses 4 and 4 ′ are attached to the tips and positioned and fixed to face each other with the optical element 1 interposed therebetween. High-frequency band light including a pair of lens holders 41, 41 'made of a mechanically strong metal material, and optical fibers 42, 42' mechanically coupled and fixed to the lens holders 41, 41 '. In the module, a high-frequency band optical module in which the distal ends of the lens holders 41 and 41 ′ were welded and fixed to the stem 3 via the electromechanical connecting portion 7 was configured.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a perspective view of an embodiment of a high-frequency band optical module, and FIG. 2 is a sectional view thereof. 1 and 2, the same reference numerals as those in FIGS. 6 and 5 denote the same members.

The optical device 1 described above with reference to FIG.
It is electro-mechanically coupled and fixed to a step 31 protruding upward from the stem 3. Stem 3 is copper tungsten alloy C
A conductor made of uW, which is grounded. A high-frequency electric waveguide 22 is formed on the surface of an electric waveguide substrate 21 made of an electrically insulating material. This electric waveguide substrate 2
1 is mechanically connected and fixed to the stem 3 in the vicinity of the optical element 1. The high-frequency electric waveguide 22 is driven by the high-frequency signal source 2 connected to one end of the high-frequency electric waveguide 22. The other end of the high-frequency signal source 2 is grounded. A terminal resistor 24 is connected to the other end of the electric waveguide 22.

The lens 4 constituting the input / output optical device is attached to the tip of a mechanically strong lens holder 41 made of a metal material. Similarly, the lens 4 'constituting the input / output optical device is attached to the tip of a mechanically strong lens holder 41' made of a metal material. Light propagates through optical fiber 42 and optical fiber 42 '. These two lenses are positioned and fixed to face each other with the optical element 1 interposed therebetween. The high-frequency band optical module includes the optical element 1 described above, a pair of a light emitting unit and a light receiving unit.

The width of the optical waveguide 11 of the optical element 1 is 1 to 2 μm.
The optical waveguide 11 and the lens 4
Unless the relative positional accuracy between ± 0.5 μm is maintained, the optical coupling efficiency deteriorates. In order to secure and maintain the relative positional accuracy, the alignment between the lens 4 and the optical waveguide 11 of the optical element 1 is performed, and then the lens holder 41 is welded to the case 6 surrounding the entire high-frequency band optical module. At the same time, the sleeve of the optical fiber 42 is fixed to the lens holder 41 by welding. Due to the need to carry out this welding fixation,
These members are made of a metal material having good weldability and high mechanical strength. In addition, as a material constituting these members, a material having the same coefficient of thermal expansion is adopted from the viewpoint of preventing axial displacement due to a temperature change.

Reference numeral 5 denotes a tubular shield made of a metal material. The tubular shield 5 includes an electric waveguide substrate 21, an electric waveguide 22 formed on a surface of the electric waveguide substrate 21,
Surrounding the step 31 projecting upward from the stem 3 and the entire optical element 1 which is electromechanically bonded and fixed to the step 31, it is welded and fixed to the conductor stem 3 made of a copper tungsten alloy CuW. You. In the tubular shield 5, a light passage hole 51 for forming an optical path between the lens 4 and the optical element 1 is formed, and a light passage hole 51 'for forming an optical path between the lens 4' and the optical element 1 is formed. Are formed.

By providing the tubular shield 5 as described above, the lens holder 41, which is a conductor, is
, The electromagnetic effect of the lens holder 41 approaching the optical element 1 is shielded by the tubular shield 5 interposed therebetween. Therefore, the spatial electromagnetic field formed by the electric waveguide 22 in the tubular shield 5 is not disturbed by the lens holder 4.
Then, the lens holder 41 is fixed to the case 6 by welding, and the optical fiber 42 is fixed to the lens holder 41.
By fixing the sleeve by welding, the mechanical configuration of the entire high-frequency band optical module can be strengthened, and the relative positional accuracy between the optical waveguide 11 and the lens 4 can be secured and maintained satisfactorily.

Referring to FIG. 4A, the optical response characteristic of the above embodiment is higher than that of the conventional example shown in FIG. 4B in a high frequency band exceeding 10 GHz. It is flat without any deterioration. To explain the second embodiment, this corresponds to the conventional example of the high-frequency band optical module described with reference to FIG. 6 in which the lens holders 41 and 41 'are made of a non-conductive material. That is, in the above embodiments, the lens holders 41 and 41 'are made of a metal material which is a mechanically strong conductor. In the second embodiment, the lens holders 41 and 41 'are made of a non-conductive material such as ceramics or glass having high mechanical strength.
Since the lens holder 41 is a non-conductive material, even if the lens holder 41 is installed close to the optical waveguide 11 of the optical element 1,
Does not have any particular electromagnetic effect, so that the spatial electromagnetic field formed by the electric waveguide 22 is not disturbed by the lens holder 4. By simply using a non-conductive material such as ceramic or glass having high mechanical strength as a constituent material of the lens holders 41 and 41 ', disturbance of the spatial electromagnetic field can be prevented very easily.

A third embodiment will be described with reference to FIG.
As in the previous embodiment, the optical element 1 is electro-mechanically coupled and fixed to a step 31 formed to protrude upward from the stem 3. The stem 3 is a conductor made of a copper tungsten alloy CuW and is grounded. A high-frequency electric waveguide 22 is formed on the surface of an electric waveguide substrate 21 made of an electrically insulating material. The electric waveguide substrate 21 is mechanically coupled and fixed to the stem 3 near the optical element 1.

The lens 4 constituting the input / output optical device is attached to the tip of a mechanically strong lens holder 41 made of a metal material via an attachment ring 411 made of a metal material. Similarly, the lens 4 ′ constituting the input / output optical device includes a mounting ring 41 made of a metal material.
It is attached to the tip of a mechanically strong lens holder 41 'made of a metal material via 1'. Light propagates through optical fiber 42 and optical fiber 42 '. These two lenses are positioned and fixed to face each other with the optical element 1 interposed therebetween. In this embodiment, the tip of the lens holder 41 and the tip of the mounting ring 411 are connected to the copper-tungsten alloy Cu
It is electro-mechanically welded and fixed to a stem 3 which is a conductor made of W. Similarly, the tip of the lens holder 41 'and the tip of the mounting ring 411' are also electromechanically welded and fixed to the stem 3 via the electromechanical connection 7 '.

Here, the tips of the lens holders 41 and 41 ′ which are installed close to the optical element 1 are connected to the stem 3 which is a conductor.
The optical element 1 and the lens holder, which are electro-mechanically welded and fixed to each other so that they are almost completely at the same potential, are eventually electro-mechanically coupled and fixed to the step 31 formed to project upward from the stem 3. 41 and 41 'can be almost completely at the same potential.

As described above, by setting the optical element 1 and the lens holders 41 and 41 'at the same potential, the lens holders 41 and 41', which are conductors, are placed close to the optical waveguide 11 of the optical element 1. Thus, the electromagnetic effect due to the above is not exerted on the optical element 1, and the spatial electromagnetic field formed by the electric waveguide 22 is prevented from being disturbed by the lens holder 4.

[0024]

As described above, according to the present invention, in the high-frequency band optical module, the spatial electromagnetic field formed by the electric waveguide is prevented from being disturbed in the vicinity of the lens holder, and the specific frequency is reduced. Deterioration of the optical response characteristics can be prevented. Thereby, a high numerical aperture N
It is possible to provide a high-frequency band optical module having a high frequency response characteristic in which the optical coupling between the optical element and the lens is performed with high efficiency by employing the lens of A.

That is, by providing the hollow shield, even if the lens holder, which is a conductor, is placed close to the optical waveguide of the optical element, the electromagnetic effect of the lens holder approaching the optical element is interposed between them. It is shielded by the hollow shield, and the spatial electromagnetic field formed by the electric waveguide in the hollow shield is not disturbed by the lens holder. By fixing the lens holder to the case by welding and fixing the optical fiber sleeve to the lens holder by welding, the mechanical structure of the entire high-frequency band optical module can be strengthened, and the optical waveguide and It is possible to satisfactorily maintain and maintain the relative positional accuracy with the lens.

Further, disturbance of the spatial electromagnetic field can be prevented very easily by simply using a non-conductive material such as ceramic or glass having high mechanical strength as a constituent material of the lens holder. Furthermore, a very simple structure in which the tip of the lens holder is welded and fixed to the stem via the electromechanical connection can prevent disturbance of the spatial electromagnetic field formed by the electric waveguide.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an embodiment.

FIG. 2 is a cross-sectional view illustrating an embodiment.

FIG. 3 is a sectional view illustrating another embodiment.

FIG. 4 is a diagram showing frequency characteristics of the high-frequency band optical module.

FIG. 5 is a sectional view of an optical element.

FIG. 6 is a perspective view illustrating a conventional example.

[Explanation of symbols]

 Reference Signs List 1 optical element 11 optical waveguide 12 p-layer 13 n-layer 14 semi-insulating layer 15 p-electrode 16 n-electrode 2 high-frequency signal source 21 electric-waveguide-forming substrate 22 electric-waveguide 23 bonding wire 24 termination resistor 3 stem 31 step 4 lens 41 Lens holder 411 Mounting ring 42 Optical fiber 5 Shield 51 Light passage hole 6 Case 7 Electromechanical connection

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-11-38372 (JP, A) JP-A-11-3904 (JP, A) JP-A-10-322028 (JP, A) JP-A 8- 5874 (JP, A) JP-A-7-263807 (JP, A) JP-A-4-39632 (JP, A) JP-A-4-152307 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) H01L 31/00-31/024 H01L 33/00 H01S 5/00-5/50 G02B 6/32 G02B 6/42 G02F 1/00-1/125

Claims (4)

(57) [Claims] 1. A stem comprising a conductive material, an optical element having a minute optical waveguide and being electromechanically coupled and fixed to the stem, and a high-frequency electric waveguide formed on a surface of the stem. An optical waveguide substrate made of an electrically insulating material that is mechanically coupled and fixed near the optical element, wherein a lens is attached to the front end, and is mechanically strong that is positioned and fixed to face each other with the optical element interposed therebetween. A high-frequency band optical module including a pair of lens holders made of a metal material and including an optical fiber mechanically coupled and fixed to the lens holder, wherein an electric waveguide formed on a surface of the electric waveguide substrate; A hollow shield made of a conductive material surrounding the entire optical element which is electro-mechanically bonded and fixed to the step portion, wherein the hollow shield forms a light passage between the lens and the optical element. A high-frequency band optical module, characterized in that: 2. The high-frequency band optical module according to claim 1, further comprising a case surrounding the entire high-frequency band optical module, wherein the optical fiber sleeve and the case have good weldability and high mechanical strength. A high frequency band optical module comprising a metallic material, wherein a lens holder is welded and fixed to a case, and an optical fiber sleeve is fixed to the lens holder by welding. 3. A stem comprising a conductive material, comprising an optical element having a minute optical waveguide and being electro-mechanically coupled and fixed to the stem, wherein a high-frequency electric waveguide is formed on a surface of the stem. A pair of lenses, comprising an electric waveguide substrate made of an electrically insulating material mechanically coupled and fixed in the vicinity of the optical element, wherein the lens is attached to the tip and positioned and opposed to each other with the optical element interposed therebetween. A high frequency band optical module comprising a holder and an optical fiber mechanically coupled and fixed to the lens holder, wherein the lens holder is made of a non-conductive material such as ceramics or glass having high mechanical strength. High-frequency band optical module. 4. A stem comprising a conductive material, comprising an optical element having a minute optical waveguide and being electro-mechanically coupled and fixed to the stem, wherein a high-frequency electric waveguide is formed on a surface of the stem. An optical waveguide substrate made of an electrically insulating material that is mechanically coupled and fixed near the optical element, wherein a lens is attached to the front end, and is mechanically strong that is positioned and fixed to face each other with the optical element interposed therebetween. In a high-frequency band optical module including a pair of lens holders made of a metal material and including an optical fiber mechanically coupled and fixed to the lens holder, a tip of the lens holder is stemmed via an electromechanical connection. A high-frequency band optical module characterized by being fixedly welded to a module.