JP2004294918A - Optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the yield by deterring loss accompanying connector connection from increasing by preventing a radiation wave leaking from a connector from entering a flank of an optical modulator. <P>SOLUTION: An optical device 10A is constituted by mounting and fixing a reverse surface 22a of a pedestal 22 on a main surface 18a of a base 18 of a housing 12 and mounting and fixing the optical modulator 14 on a main surface 22b of the pedestal 22; and a main surface 30a of an optical waveguide substrate 30 of the optical modulator 13 and a reverse surface 30b of the optical waveguide substrate 30 are nearly parallel to each other and the angle θ that the main surface 22b of the pedestal 22 and the reverse surface 22a of the pedestal 22 contain is <0 to <90. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical device having an optical element in which one or more optical waveguides are formed on a substrate having an electro-optical effect and one or more electrodes are provided on a main surface of the substrate.
[0002]
[Prior art]
In recent years, with the development of multimedia, demand for broadband communication has increased, and an optical transmission system exceeding 10 Gb / s has been put into practical use, and further higher speed is expected.
[0003]
As a device for modulating an electric signal (microwave signal) of 10 Gb / s or more into light, an LN optical modulator is used. When a microwave signal of 10 Gb / s or more is supplied to an optical modulator, the following microwave attenuation becomes a problem (for example, see Patent Document 1).
(1) Conductor loss of microwave line
(2) Dielectric loss due to LN substrate, buffer layer and low dielectric constant layer
(3) Loss due to higher-order mode propagation
(4) Microwave line bending and taper loss
(5) Impedance mismatch with external circuit
(6) Loss due to the mounting package including the loss in the contact with the connector and the connector line, and the loss due to the outer package
[0004]
In the technique described in Patent Document 1, in order to solve the above-described problem, at least a dielectric substrate and a metal substrate located below a signal electrode layer and a ground electrode formed on a crystal substrate having an optical waveguide are used. A groove for forming an air gap is provided on one side.
[0005]
[Patent Document 1]
JP-A-10-142567 (paragraphs [0003] to [0006])
[0006]
[Problems to be solved by the invention]
The present inventors have proposed a method for solving the above-mentioned problem. That is, as a configuration for improving the loss due to the higher-order mode propagation of the above (3), a structure in which a conductive layer is provided between a modulator substrate and a support substrate in a modulator having an LN thin plate structure is proposed.
[0007]
By forming a conductive layer between the modulator substrate and the reinforcing substrate, the invasion of unnecessary waves (radiated waves) in the substrate thickness direction can be cut at the surface of the reinforcing substrate (the electric field becomes zero at the conductive layer), Ripple due to substrate resonance can be shifted to the high frequency side, and high frequency loss can be dramatically improved.
[0008]
Further, the present inventors have tried to reduce the microwave attenuation by focusing on the reduction of the loss due to the connector connection of (6).
[0009]
Here, regarding the connection structure between the optical modulator and the connector, the first optical device 100A includes an optical modulator 102 and an optical modulator 102 as shown in FIG. And a metal housing 104 provided so as to be supported. The optical modulator 102 is a modulation device including an optical waveguide (not shown) formed immediately below a main surface of a substrate 106 having an electro-optical effect, and a signal electrode layer 108 and a ground electrode 110 formed on the main surface of the substrate 106. It has an electrode 112 and a pedestal 114 for supporting the substrate 106.
[0010]
The housing 104 has a base 116 on which the base 114 is mounted and fixed, and a side plate 118 located on the side of the optical modulator 102.
[0011]
Further, a feedthrough substrate 120 made of, for example, a ceramic material is provided between the optical modulator 102 and the side plate 118 of the housing 104. A coplanar line and a strip line line are provided on the upper surface of the feedthrough substrate 120, a signal electrode layer 122 is formed substantially at the center thereof, and a ground electrode layer 124 is formed on both sides of the signal electrode layer 122. I have. The feed-through board 120 is provided with a through-hole 126, and the base 116 and the grounding electrode layer 124 are electrically connected through the through-hole 126.
[0012]
A connector 128 is fitted into the side plate 118. The connector 128 has a cylindrical glass bead 130 for insulation and a metal connecting pin 132 coaxially mounted in the glass bead 130. Solder fixed.
[0013]
Among the electrode layers formed on the feed-through substrate 120, the signal electrode layer 122 formed substantially at the center is an electrode for supplying a predetermined modulation signal to the signal electrode layer 108 of the optical modulator 102 from an external power supply (not shown). Used as The connection pins 132 of the connector 128 are electrically connected to the signal electrode layer 122 by solder, conductive paste, or the like.
[0014]
Further, the signal electrode layer 122 and the signal electrode layer 108 of the optical modulator 102 are electrically connected by a bonding wire 134 such as a ribbon, and the ground electrode layer 124 and the ground electrode 110 of the optical modulator 102 are They are electrically connected by bonding wires 136.
[0015]
The second optical device 100B has substantially the same configuration as the above-described first optical device 100A, as shown in FIG. The side surface 102 and the side plate 118 of the housing 104 are configured to be in contact with each other. In this case, the connection pin 132 of the connector 128 is directly electrically connected to the signal electrode layer 108 of the optical modulator 102 by solder or conductive paste, and the ground electrode 110 of the optical modulator 102 and the side plate 118 are connected by, for example, a ribbon wire 140. It is electrically connected.
[0016]
In the first and second optical devices 100A and 100B, the optical devices are mounted such that the axial direction of the connection pins 132 of the connector 128 and the normal direction of the main surface of the substrate 106 are perpendicular to each other. Representatively, a side view of the second optical device 100B is shown in FIG. FIG. 15 also shows a Mach-Zehnder optical waveguide 142 formed immediately below the main surface of the substrate 106.
[0017]
However, in the case of such first and second optical devices 100A and 100B, the radiation wave leaked from the connection pin 132 of the connector 128 propagates toward the substrate 106 of the optical modulator 102 and couples with the substrate 106. Therefore, there is a problem that the influence of resonance in the substrate 106 becomes remarkable.
[0018]
Usually, like the second optical device 100B in FIG. 14, the side surface of the optical modulator 102 is brought into close contact with the side plate 118 of the housing 104, or the ground electrode 110 of the optical modulator 102 is electrically connected to the housing 104. Although the potential is set to be equal, the radiation wave enters from the side surface of the substrate 106, so that the characteristics are insufficient and the yield may be deteriorated.
[0019]
The present invention has been made in consideration of such a problem, and can prevent a radiation wave leaking from a connector from entering a side surface of an optical modulator, and suppress an increase in loss due to connector connection. It is an object of the present invention to provide an optical device capable of improving the yield while improving the yield.
[0020]
[Means for Solving the Problems]
An optical device according to the present invention includes an optical element in which one or more optical waveguides are formed on a substrate having an electro-optic effect, and one or more electrodes are provided on a main surface of the substrate. A connector for supplying power to one or more electrodes, wherein the connector has a columnar conductor electrically connected to a signal electrode layer to which a signal is supplied, among the one or more electrodes of the optical element. The angle θ between the axial direction of the conductor and the main surface of the substrate is 0 ° <θ <90 °.
[0021]
Thereby, the angle between the axial direction of the columnar conductor in the connector and the main surface of the substrate is θ, so that it is possible to suppress radiation waves leaked from the columnar conductor from entering the side surface of the substrate.
[0022]
Also, when the conductor of the connector is electrically connected to the electrode of the optical modulator, the pressing force at the connection point between the conductor and the electrode is usually controlled in the contact work, but this control requires skill. Was. That is, if the pressing force at the connection point is too strong, cracks may occur on the substrate of the optical modulator, and if the pressing force is too weak, the high-frequency characteristics may deteriorate.
[0023]
However, according to the present invention, if a substrate, a connector, and the like are manufactured in a predetermined size, the positioning can be easily performed only by sliding the optical modulator, and the conductor and the electrode come into contact with each other. Can be done easily. In addition, the probability of cracking is reduced, and the yield is improved.
[0024]
The conductor may be in direct contact with the signal electrode layer, or may be connected to the signal electrode layer via a stress relief member. A feed-through board may be interposed between the board and the conductor. The thickness of the substrate may be 30 μm or less. Further, a support substrate may be fixed to the back surface of the substrate.
[0025]
Further, in the above configuration, the electronic device further includes a housing that houses the optical element and the connector, the housing includes a base and a side plate, and the optical element is mounted on the base via a pedestal. The connector may be fixed, and the conductor of the connector may be inserted through the side plate.
[0026]
When the optical element is mounted and fixed on the main surface of the pedestal, the main surface of the substrate and the back surface of the substrate in the optical element are substantially parallel to each other, and the main surface of the pedestal and the base The angle formed by the back surface may be 0 ° <θ <90 °.
[0027]
In addition, the pedestal may be installed afterwards on the housing, or may be provided integrally with the housing.
[0028]
A part of the side surface of the substrate may directly contact the side wall. Means for controlling the impedance of the optical element may be interposed between the side wall and the side surface of the substrate.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an optical device according to the present invention will be described with reference to FIGS. 1, 4 and 5, a part of the optical device is shown in a simplified manner.
[0030]
First, the optical device 10A according to the first embodiment has a housing 12, an optical modulator 14, and a connector 16, as shown in FIG.
[0031]
The housing 12 has a metal base 18 and a metal side plate 20, and has a substantially L-shape when viewed from the side. The optical modulator 14 is mounted and fixed on the base 18 via a metal pedestal 22.
[0032]
The connector 16 is fitted into the side plate 20 of the housing 12. The connector 16 has a cylindrical glass bead 24 fixed by solder in a hole provided in the side plate 20 for insulation, and a metal connection mounted coaxially in the glass bead 24. And a pin 26. A stress relief member 28 is attached to the tip of the connection pin 26. Of course, it is not necessary to attach such a stress relief member 28.
[0033]
As shown in FIG. 2, the optical modulator 14 includes an optical waveguide substrate 30 made of an X-cut plate of lithium niobate, and a Mach-Zehnder type formed directly below the main surface of the optical waveguide substrate 30 by a titanium diffusion method or the like. An optical waveguide 32, a buffer layer (not shown) made of silicon oxide or the like, and a coplanar (CPW) modulation electrode layer (first and second ground electrodes 34A and 34B, Signal electrode layer 36).
[0034]
The Mach-Zehnder optical waveguide 32 has a form in which one optical waveguide 32A is branched into two optical waveguides 32B and 32C, and although not shown, the optical waveguide 32A is multiplexed with one optical waveguide 32A again. The modulation electrode layer includes a center electrode 36 as a signal line and ground electrodes 34A and 34B on both sides, and forms a so-called coplanar (CPW) electrode.
[0035]
The optical device 10A according to the first embodiment has a pedestal 22 provided on a main surface 18a of a base 18 of a housing 12 as shown in FIGS. The main surface 30a of the optical waveguide substrate 30 and the back surface 30b of the optical waveguide substrate 30 in the optical modulator 14 are substantially parallel to each other, and the main surface of the pedestal 22 is provided. The angle θ between the base 22b and the back surface 18b of the base is 0 ° <θ <90 °. The pedestal 22 may be installed later on the main surface 18 a of the base 18 or may be provided integrally with the base 18.
[0036]
Thus, the optical modulator 14 is mounted on the pedestal 22 and a part (upper end) of one side surface 30c of the optical waveguide substrate 30 (hereinafter, also referred to as one side surface 30c of the optical modulator 14). When the edge is brought into contact with the side plate 20, the angle θ between the axial direction of the connection pin 26 of the connector 16 and the main surface 30a of the optical waveguide substrate 30 is 0 ° <θ <90 °. At this time, the connection pin 26 of the connector 16 comes into direct contact with the signal electrode layer 36 of the optical modulator 14 or is connected via the stress relief member 28. The amount of protrusion may be adjusted.
[0037]
As shown in FIG. 1, the connection pin 26 of the connector 16 is electrically connected directly to the signal electrode layer 36 of the optical modulator 14 by solder or conductive paste, and the first and second grounds of the optical modulator 14 are formed. The electrodes 34A and 34B and the side plate 20 are electrically connected, for example, by a ribbon wire 38.
[0038]
When a part of one side surface 30c of the optical modulator 14 is brought into contact with the side plate 20 of the housing 12, a wedge-shaped gap is generated between the one side surface 30c of the optical modulator 14 and the side plate 20. This gap may be air, but as shown in FIG. 3, a wedge-shaped metal spacer 40 may be fixed in advance so as to fill the gap.
[0039]
As described above, in the optical device 10A according to the first embodiment, the angle θ between the axial direction of the connection pin 26 of the connector 16 and the main surface 30a of the optical waveguide substrate 30 is 0 ° <θ <90 °. Therefore, it is possible to suppress the radiation wave leaked from the connection pin 26 from entering the one side surface 30c of the optical waveguide substrate 30.
[0040]
In the case where the connection pin 26 of the connector 16 is electrically connected to the signal electrode layer 36 of the optical modulator 14, usually, in a contact operation, the pressing force at the connection point between the connection pin 26 and the signal electrode layer 36 is controlled. However, this control requires skill. That is, when the substrate thickness of the optical waveguide substrate 30 is 30 μm or less, cracks may occur in the optical waveguide substrate 30 of the optical modulator 14, particularly when the pressing force at the connection point is too strong, and conversely, If the pressing force is too weak, the high-frequency characteristics may be deteriorated.
[0041]
However, in the first embodiment, if the side plate 20, the base 18, the pedestal 22, the optical waveguide board 30, the connector 16 and the like of the housing 12 are manufactured with the dimensions specified in advance, the optical modulator 14 Can be easily positioned simply by sliding the contact pins, and the contact work can be easily performed because the connection pins 26 and the signal electrode layers 36 are in contact with each other or are connected via the stress relief members 28. In addition, the probability of cracking is reduced, and the yield is improved.
[0042]
The optical waveguide substrate 30 is made of a ferroelectric electro-optic material, preferably, a single crystal. Such a crystal is not particularly limited as long as light can be modulated. However, lithium niobate, lithium tantalate, lithium niobate-lithium tantalate solid solution, potassium lithium niobate, KTP (KTiOPO4: potassium titanyl phosphate), GaAs (Gallium arsenide) and quartz can be used. Even in the case of an anisotropic substrate, it does not depend on the substrate orientation.
[0043]
The material of the first and second ground electrodes 34A and 34B and the signal electrode layer 36 is not particularly limited as long as it is a material having low resistance and excellent impedance characteristics, and gold, silver, copper, or the like may be used. it can.
[0044]
For the buffer layer, a material such as silicon oxide, magnesium fluoride, silicon nitride, or alumina can be used.
[0045]
The optical modulator 14 was formed by forming the first and second ground electrodes 34A and 34B and the signal electrode layer 36 on the main surface 30a of the optical waveguide substrate 30 via a buffer layer (not shown). However, in addition, first to fourth optical modulators 14A to 14D described later can be used.
[0046]
Next, an optical device 10B according to a second embodiment will be described with reference to FIG.
[0047]
As shown in FIG. 4, the optical device 10B according to the second embodiment includes a side surface of the pedestal 22 (and one side surface 30c of the optical modulator 14 (see FIG. 3)) and the side plate 20 of the housing 12. The difference is that a feed-through substrate 50 made of, for example, a ceramic material is provided between them. In this example, the case where the stress relief member 28 is not attached to the tip of the connection pin 26 of the connector 16 is shown.
[0048]
A coplanar electrode is formed on the upper surface of the feedthrough substrate 50, and first and second grounding electrode layers 54A and 54B are formed on both sides of the center electrode 52. The feed-through board 50 is provided with a through-hole 56, and the base 18 is electrically connected to the first and second grounding electrode layers 54 </ b> A and 54 </ b> B via the through-hole 56.
[0049]
Of the electrode layers formed on the feed-through substrate 50, the center electrode 52 is used as an electrode for supplying a predetermined modulation signal to the signal electrode layer 36 of the optical modulator 14 from an external power supply (not shown). The connection pin 26 of the connector 16 is electrically connected to the center electrode 52 by solder, conductive paste, or the like.
[0050]
Further, the center electrode 52 and the signal electrode layer 36 of the optical modulator 14 are electrically connected by a bonding wire 58 such as a ribbon, and the first and second grounding electrode layers 54A and 54B and the The first and second ground electrodes 34A and 34B are electrically connected by a bonding wire 60 such as a ribbon.
[0051]
The impedance of the optical modulator 14 can be controlled by appropriately adjusting the thickness and length of the connection pin 26 of the connector 16. That is, the connection pins 26 of the connector 16, the feed-through board 50, and the signal electrode layer 52 formed on the feed-through board 50 function as a means for controlling the impedance of the optical modulator 14.
[0052]
Also in the second embodiment, since the angle θ between the axial direction of the connection pin 26 of the connector 16 and the main surface 30a of the optical waveguide board 39 is 0 ° <θ <90 °, the leakage from the connection pin 26 It is possible to suppress the radiated wave from entering from one side surface 30c of the optical waveguide substrate 30. Also, when manufacturing the optical device 10B, the feed-through substrate 50 is fixed on the base 18 by contacting the side plate 20, and then the pedestal 22 is fixed beside the feed-through substrate 50. By simply sliding the device 14 on the pedestal 22 toward the feed-through substrate 50, the optical modulator 14 can be easily positioned at a predetermined position.
[0053]
In the above-described example, the signal electrode layer 52 is formed by providing a coplanar line on the upper surface of the feed-through substrate 50, and the connection pins 26 are brought into contact with the signal electrode layer 52. Like the optical device 10Ba, the concave portion 62 may be formed at a position corresponding to the connection pin 26 on the upper surface of the feed-through substrate 50 so that the connection pin 26 does not contact the feed-through substrate 50. In this case, a ground electrode 54 is formed on the upper surface of the feedthrough substrate 50.
[0054]
As shown in FIG. 6, the width Dc of the recess 62 provided in the feed-through board 50 and the distance Db from the center of the connection pin 26 to the wall surface of the recess 62 are appropriately determined with respect to the thickness Da of the connection pin 26. By adjusting, the impedance of the optical modulator 14 can be controlled.
[0055]
When the inside of the concave portion 62 is air (when the inside of the concave portion 62 is filled with air), preferably, the ratio (the width Dc of the concave portion 62 / the thickness Da of the connection pin 26) is set to 1 to 4. Thereby, the impedance of the optical modulator 14 can be easily set to a practical level, for example, 50Ω. In this case, the width Dc of the concave portion 62 may be set to twice or less the distance Db from the center of the connection pin 26 to the wall surface of the concave portion 62.
[0056]
On the other hand, when the recess 62 is filled with a dielectric material, the thickness Da of the connection pin 26, the width Dc of the recess 62, and the distance Db from the center of the connection pin 26 to the wall surface of the recess 62 are determined in vacuum. What is necessary is just to satisfy the above requirements when converted to the effective distance.
[0057]
The optical modulator 14 was formed by forming the first and second ground electrodes 34A and 34B and the signal electrode layer 36 on the main surface 30a of the optical waveguide substrate 30 via a buffer layer (not shown). However, besides, first to fourth optical modulators 14A to 14D described later can be used.
[0058]
Next, an example of a preferable configuration of the optical modulator in the optical devices 10A and 10B according to the above-described first and second embodiments will be described with reference to FIGS.
[0059]
As shown in FIG. 7, the first optical modulator 14A is thinned until the thickness of the optical waveguide substrate 30 becomes 30 μm or less. In the optical waveguide substrate 30, a portion including the Mach-Zehnder type optical waveguides 32B and 32C is a first thin portion 70 having a thickness of 30 μm or less, and a portion adjacent to the first thin portion 70 is the first thin portion 70. The second thin portion 72 is thinner than the first thin portion 70. The difference between the thickness of the first thin portion 70 and the thickness of the second thin portion 72 is 1 μm or more.
[0060]
In the first optical modulator 14A, a support substrate 74 is attached to the back surface of the optical waveguide substrate 30 using a thermosetting resin such as an epoxy-based film. The support substrate 74 has a groove 76 formed at a position corresponding to the first and second thin portions 70 and 72 of the optical waveguide substrate 30, and the first and second thin portions 70 and 72 of the optical waveguide substrate 30, One cavity 78 is formed in the groove 76 of the support substrate 74.
[0061]
In this case, since the modulation signal from the signal electrode layer 36 seeps into the cavity 78 (air) existing below the second thin portion 72, the speed matching condition can be satisfied without forming the buffer layer described above. Further, since the modulation signal is efficiently applied to the optical waveguides 32B and 32C, the driving voltage of the first optical modulator 14A can be reduced.
[0062]
Next, as shown in FIG. 8, the second optical modulator 14B is thinned until the thickness of the optical waveguide substrate 30 becomes 30 μm or less, and particularly includes the branch portions 32B and 32C of the Mach-Zehnder optical waveguide. The portion is formed to be thinner and is a thin portion 80.
[0063]
A support substrate 74 is attached to the back surface of the optical waveguide substrate 30 using a thermosetting resin such as SOG (SPIN on GLASS) or an epoxy film. The support substrate 74 has a groove 76 formed in a portion corresponding to the thin portion 80 of the optical waveguide substrate 30, and one hollow portion is formed by the thin portion 80 of the optical waveguide substrate 30 and the groove 76 of the support substrate 74. It has become. This hollow portion is filled with a dielectric material 82. That is, when the stacking relation of the portions including the optical waveguides 32B and 32C is viewed, from the bottom, a three-layer structure of the support substrate 74, the low dielectric material 82, and the optical waveguide substrate 30 is formed.
[0064]
Also in this case, the drive voltage of the optical modulator 14 can be reduced because the speed matching condition can be satisfied and the modulation signal can be efficiently applied to the optical waveguides 32B and 32C without forming the buffer layer described above. Can be. In addition, there is an advantage that the mechanical strength is higher than that of the first optical modulator 14A.
[0065]
Next, as shown in FIG. 9, the third optical modulator 14C is thinned until the thickness of the optical waveguide substrate 30 becomes 30 μm or less, and the support substrate 74 is provided on the back surface of the thinned optical waveguide substrate 30. (For a specific method of bonding, see Example 3 described later). Also in this case, the speed matching condition can be satisfied without forming the above-described buffer layer, and the modulation signal is efficiently applied to the optical waveguides 32B and 32C. Therefore, the driving voltage of the third optical modulator 14C is reduced. Can be reduced. In addition, there is an advantage that the mechanical strength is higher than those of the first and second optical modulators 14A and 14B.
[0066]
Next, as shown in FIG. 10, the fourth optical modulator 14D has substantially the same configuration as the third optical modulator 14C, but the main surface of the support substrate 74 (the optical waveguide substrate 30 is attached). This is different in that a conductive layer 84 of Au or the like is formed on the (surface).
[0067]
In this case, invasion of unnecessary waves (radiated waves) in the thickness direction of the substrate can be cut (the electric field becomes zero by the conductive layer 84) on the surface of the support substrate 74. Therefore, the ripple due to the substrate resonance can be shifted to the high frequency side, and the high frequency loss can be remarkably improved.
[0068]
【Example】
(Example 1)
An optical modulator 14 similar to the optical device 10A according to the first embodiment was used as the optical modulator. That is, a Ti diffusion waveguide is formed directly below the main surface 30a of an optical waveguide substrate 30 made of an X-cut plate of lithium niobate, and a buffer layer and a CPW electrode (the first and second ground electrodes 34A) are formed on the main surface 30a. 34B and the signal electrode layer 36).
[0069]
Next, after the optical waveguide substrate 30 is cut into chips, the end surface is polished, the optical axis is adjusted with the optical fiber, and the optical fiber is adhered and fixed with a UV curable resin to produce a pigtail device (optical modulator 14). . Further, as shown in FIG. 1, glass beads 24 for a V connector were fixed in advance to the side plate 20 of the metal housing 12 by soldering. The pedestal 22 on which the optical waveguide substrate 30 is mounted and fixed is adjusted so that the angle θ between the axial direction of the connection pin 26 projecting from the center of the glass bead 24 and the main surface 30a of the optical waveguide substrate 30 is 30 °. The height of the connection pin 26 was adjusted so that the tip of the connection pin 26 was in contact with the signal electrode layer 36 formed on the optical waveguide substrate 30.
[0070]
Accordingly, by placing the optical modulator 14 on the pedestal 22 and sliding the optical modulator 14 toward the side plate 20 to bring one side surface 30 c of the optical modulator 14 into contact with the side plate 20, the connection pin 26 is automatically connected to the optical waveguide. An angle of 30 ° is formed with respect to the main surface 30a of the substrate 30, and the substrate 30 is electrically connected to the signal electrode layer. At this stage, the optical modulator 14 is fixed, the connection pin 26 and the signal electrode layer 36 are electrically connected by solder or conductive paste, and further, the first and second ground electrodes 34A and 34A of the optical modulator 14 are 34B and the side plate 20 were electrically connected by a ribbon wire 38, for example.
[0071]
As a characteristic evaluation, the S21 characteristic was measured with a vector network analyzer. As a result, a frequency characteristic without ripple was shown up to fr = 50 GHz.
[0072]
(Example 2)
In the first embodiment described above, the connection between the connection pin 26 and the signal electrode layer 36 was performed via the stress relief member 28.
[0073]
Before mounting the optical modulator 14 on the pedestal 22, a stress relief member 28 is attached to the tip of the connection pin 26, and then the optical modulator 14 is mounted on the pedestal 22 as in the first embodiment. The optical modulator 14 was fixed by sliding toward the side plate 20.
[0074]
As a characteristic evaluation, the S21 characteristic was measured with a vector network analyzer. As a result, a frequency characteristic without ripple was shown up to fr = 50 GHz.
[0075]
(Example 3)
The third light modulator 14C shown in FIG. 9 was used as the light modulator. That is, first, a 0.3 mm thick X-cut LiNbO ₃ (LN) Two sets of substrates were immersed for about 15 minutes, washed with pure water, and then spin-dried.
[0076]
Next, after spin-coating SOG (SPIN on GLASS) on the surfaces of the two sets of LN substrates at 1000 rpm, the coated surfaces are overlapped with each other and a load is applied thereto, and at a temperature of 1070 ° C. for 3 hours in a steam-containing oxygen atmosphere. Then, the two sets of LN substrates were bonded.
[0077]
Next, one of the two sets of the bonded LN substrates was heated and attached to a polishing platen using wax. Thereafter, by performing horizontal polishing and polishing (CMP), of the two sets of LN substrates, the LN substrate constituting the optical waveguide substrate 30 of the third optical modulator 14C was processed to a thickness of 10 μm. .
[0078]
Next, by heating the wax, the two sets of LN substrates were removed from the polishing platen, and the two sets of LN substrates were subjected to organic solvent cleaning and UV cleaning.
[0079]
Next, after depositing a Ti film to a thickness of 500-1000 ° on the main surface of the thinned LN substrate of the two sets of LN substrates by a sputtering method, a resist pattern is formed using lithography technology. A Ti pattern was formed by RIE (reactive ion etching).
[0080]
Next, the assembly (work) formed as described above was held at 1020 ° C. for 10 hours in an oxygen atmosphere containing water vapor to form a Ti-diffused optical waveguide in the thinned LN substrate. Next, a signal electrode layer 36 made of Au and first and second ground electrodes 34A and 34B were formed through a lithography process using a thick film resist and a cyan Au plating process. FIG. 9 shows a cross section of the manufactured third optical modulator 14C.
[0081]
Next, the end face of the assembly formed as described above is polished, cut into chips by dicing to produce a third optical modulator 14C, and an optical fiber is attached to the end face of the third optical modulator 14C. The optical axis was adjusted and connected to form a pictil device.
[0082]
Further, glass beads 24 for a V connector were fixed in advance to the side plate 20 of the metal housing 12 by soldering. The pedestal 22 on which the optical waveguide substrate 30 is mounted and fixed is set so that the axial direction of the connection pin 26 projecting from the center of the glass bead 24 and the main surface of the optical waveguide substrate 30 are 30 °, and the connection pin 26 Was processed by adjusting the height so that the tip of the substrate was in contact with the signal electrode layer 36 formed on the optical waveguide substrate 30. At this time, the connection pins do not need to be touched by an operator.
[0083]
Accordingly, the third light modulator 14C is placed on the pedestal 22, slid toward the side plate 20, and one side surface 30c of the third light modulator 14C is brought into contact with the side plate 20, thereby automatically. The connection pins 26 make an angle of 30 ° with the main surface 30a of the optical waveguide substrate 30, and are electrically connected to the signal electrode layer 36. At this stage, the third optical modulator 14C is fixed, the connection pin 26 and the signal electrode layer 36 are electrically connected with solder or conductive paste, and the first and second optical modulators 14C The two ground electrodes 34A and 34B and the side plate 20 were electrically connected by, for example, a ribbon wire 38. In this connector connection, no crack was formed in the optical waveguide substrate 30 of the third optical modulator 14C.
[0084]
As a characteristic evaluation, the S21 characteristic was measured with a vector network analyzer. As a result, a frequency characteristic without ripple was shown up to fr = 50 GHz.
[0085]
(Example 4)
The fourth light modulator 14D shown in FIG. 10 was used as the light modulator. That is, in the third embodiment described above, before bonding the two sets of LN substrates, an Au film is deposited by 1 μm on the surface of the non-thinned LN substrate (the surface to which the thinned LN substrate is bonded), and the other is deposited. It was adhesively fixed to the LN substrate. Thereafter, it was manufactured in the same manner as in Example 3 to obtain a pigtail device (fourth optical modulator 14D).
[0086]
Next, similarly to the third embodiment, glass beads 24 for a V connector were fixed in advance to the side plate 20 of the metal housing 12 by soldering. Further, a stress relief contact V110-1 (stress relief member 28) made by Anritsu is inserted into the tip of the connection pin 26 of the connector 16.
[0087]
In the die bonding of the optical waveguide substrate 30, the pedestal 22 on which the optical waveguide substrate 30 is mounted and fixed is connected to the axial direction of the connection pin 26 projecting from the center of the glass bead 24 and the main surface of the optical waveguide substrate 30. ° and the height was adjusted so that the tip of the connection pin 26 was in contact with the signal electrode layer 36 formed on the optical waveguide substrate 30. The connection pin 26 and the stress relief member 38 are designed so that an operator does not need to touch it.
[0088]
Therefore, the fourth light modulator 14D is placed on the pedestal 22, slid toward the side plate 20, and one side surface 30c of the fourth light modulator 14D is brought into contact with the side plate 20, thereby automatically. The connection pin 26 forms an angle of 30 ° with the main surface 30a of the optical waveguide substrate 30, and is electrically connected to the signal electrode layer 36 via the stress relief member 28. At this stage, the fourth optical modulator 14D is fixed, the connection pin 26 and the signal electrode layer 36 are electrically connected with solder or conductive paste, and the first and second optical modulators 14D are further connected. The two ground electrodes 34A and 34B and the side plate 20 were electrically connected by, for example, a ribbon wire 38. In this connector connection, no crack was formed in the optical waveguide substrate 30 of the fourth optical modulator 14D.
[0089]
As a characteristic evaluation, the S21 characteristic was measured with a vector network analyzer. As a result, as shown in FIG. 11, a frequency characteristic having no ripple up to fr = 50 GHz was shown.
[0090]
(Example 5)
In the same manner as in Example 4, a pigtail device of the fourth optical modulator 14D was manufactured. Thereafter, a conductive paste was applied to the side surface of the fourth optical modulator 14D as a measure against pyroelectricity. Finally, the same conductive paste was applied to part of the back surface of the optical modulator, and both side surfaces were short-circuited. Next, the connector 16 having the connection pins 26 protruding from the glass beads 24 was prepared, and the glass beads 24 of the connector 16 were fixed to the side plate 20 of the metal housing 12 with AuSn solder. As shown in FIG. 5, a feed-through board 50 was provided between the side surface of the pedestal 22 and the side plate 20 of the housing 12. The feed-through substrate 50 is made of, for example, alumina, and has a surface plated with Au. In addition, similarly to FIG. 5, a concave portion 62 is formed on the main surface of the feed-through substrate 50.
[0091]
Next, only the connection pins 26 are pulled out from the glass beads 24. At this time, the connection pin 26 pulls out the upper side of the concave portion 62 of the feed-through board 50 so as to bridge. In addition, an Anritsu stress relief contact V110-1 (stress relief member 28) is attached to the tip of the connection pin 26.
[0092]
In the die bonding of the optical waveguide substrate 30, the pedestal 22 on which the optical waveguide substrate 30 is mounted and fixed is connected to the axial direction of the connection pin 26 projecting from the center of the glass bead 24 and the main surface of the optical waveguide substrate 30. ° and the height was adjusted so that the tip of the connection pin 26 was in contact with the signal electrode layer 36 formed on the optical waveguide substrate 30. The connection pin 26 and the stress relief member 28 are designed so that an operator does not need to touch it by hand.
[0093]
Therefore, the fourth light modulator 14D is placed on the pedestal 22, slid toward the side plate 20, and one side surface 30c of the fourth light modulator 14D is brought into contact with the side plate 20, thereby automatically. The connection pins 26 make an angle of 30 ° with the main surface of the optical waveguide substrate 30 and are electrically connected to the signal electrode layer 36 via the stress relief member 28. At this stage, the fourth optical modulator 14D is fixed, the connection pin 26 and the signal electrode layer 36 are electrically connected with solder or conductive paste, and the first and second optical modulators 14D are further connected. The two ground electrodes 34A and 34B and the ground electrode 54 formed on the upper surface of the feedthrough substrate 50 were electrically connected by, for example, a ribbon wire 60. In this connector connection, no crack was formed in the optical waveguide substrate 30 of the fourth optical modulator 14D.
[0094]
As a characteristic evaluation, the S21 characteristic was measured with a vector network analyzer. As a result, a frequency characteristic without ripple was shown up to fr = 50 GHz.
[0095]
According to the results of Examples 1 to 5 described above, the same effect can be obtained regardless of the presence or absence of the pyroelectric side electrode.
[0096]
(Comparative Example 1)
In the same manner as in Example 3, a pigtail device using the third optical modulator 14C was manufactured. Glass beads 24 for a V connector were fixed in advance to the side plate 20 of the metal housing 12 by soldering.
[0097]
Then, in the die bonding of the optical waveguide substrate 30, the axial direction of the connection pin 26 protruding from the glass beads 24 and the main surface of the optical waveguide substrate 30 were made parallel. In this case, since the height of the connection pin 26 and the signal electrode layer 36 are almost the same, the connection pin 26 is slightly raised, and the third optical modulator 14C is inserted and mounted on the pedestal 22. The connection pins 26 are adjusted in height and connected to the signal electrode layer 36 to fix the third optical modulator 14C by die bonding. Excessive pressure may be applied to the optical waveguide substrate 30 when adjusting the height of the connection pin 26. In some cases, cracks may occur in the optical waveguide substrate 30, and the yield was 50%.
[0098]
As a characteristic evaluation, the S21 characteristic was measured by a vector network analyzer. As a result, as shown in FIG. 12, ripple occurred at fr = 30 GHz.
[0099]
(Comparative Example 2)
In the same manner as in Example 4, a pigtail device having the fourth optical modulator 14D was manufactured. Glass beads 24 for a V connector were fixed in advance to the side plate 20 of the metal housing 12 by soldering. Furthermore, an Anritsu stress relief contact V110-1 (stress relief member 28) is inserted into the tip of the connection pin 26.
[0100]
In the die bonding of the optical waveguide substrate 30, the axial direction of the connection pin 26 and the main surface of the optical waveguide substrate 30 were made parallel. In this case, since the height of the signal electrode layer 36 is almost the same as that of the portion on which the stress relief member 28 is mounted, the connection pin 26 is slightly raised, and the fourth optical modulator 14D is placed on the pedestal 22. Then, the connection pins 26 are adjusted in height and connected to the signal electrode layer 36, and the fourth optical modulator 14D is fixed by die bonding. Excessive pressure may be applied to the optical waveguide substrate 30 when adjusting the height of the connection pin 26. In some cases, cracks may occur in the optical waveguide substrate 30, and the yield was 70%.
[0101]
As a characteristic evaluation, the S21 characteristic was measured with a vector network analyzer. As a result, a frequency characteristic without ripple was shown up to fr = 50 GHz.
[0102]
In the above-described first to fifth embodiments, package mounting (mounting on the housing 12) is performed after the pigtail device is manufactured. After performing die bonding and connector connection, adjust the optical axis with the optical fiber, adhere and fix with a UV curable resin, and obtain the same effects as described above even if a pigtail device (optical modulator 14) is manufactured. Can be.
[0103]
In addition, the optical device according to the present invention is not limited to the above-described embodiment, but can adopt various configurations without departing from the gist of the present invention.
[0104]
【The invention's effect】
As described above, according to the optical device of the present invention, it is possible to prevent the radiation wave leaking from the connector from entering the side surface of the optical modulator, and to suppress an increase in loss due to connector connection. And the yield can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a part of an optical device according to a first embodiment.
FIG. 2 is a plan view partially showing an optical modulator mounted on the optical device according to the first embodiment;
FIG. 3 is a longitudinal sectional view showing the optical device according to the first embodiment.
FIG. 4 is a perspective view showing an optical device according to a second embodiment with a part thereof omitted;
FIG. 5 is a perspective view showing a modification of the optical device according to the second embodiment with a part thereof omitted;
FIG. 6 is an explanatory diagram showing impedance adjustment in a modification of the optical device according to the second embodiment.
FIG. 7 is a cross-sectional view illustrating a first optical modulator.
FIG. 8 is a sectional view showing a second optical modulator.
FIG. 9 is a cross-sectional view illustrating a third optical modulator.
FIG. 10 is a sectional view showing a fourth optical modulator.
FIG. 11 is a view showing S21 characteristics of Example 4.
FIG. 12 is a diagram showing S21 characteristics of Comparative Example 1.
FIG. 13 is a perspective view showing a first optical device according to a conventional example with a part thereof omitted.
FIG. 14 is a perspective view showing a second optical device according to a conventional example with a part thereof omitted.
FIG. 15 is a longitudinal sectional view showing a second optical device according to a conventional example.
[Explanation of symbols]
10A, 10B, 10Ba: Optical device 12: Housing
14, 14A to 14D: optical modulator 16: connector
18 ... base 20 ... side plate
22 pedestal 26 connection pin
28: Stress release member 30: Optical waveguide substrate
36 ... signal electrode layer 50 ... feedthrough substrate

Claims (10)

An optical element in which one or more optical waveguides are formed on a substrate having an electro-optic effect, and one or more electrodes are provided on a main surface of the substrate;
A connector for supplying power to the one or more electrodes of the optical element,
The connector has a columnar conductor electrically connected to a signal electrode layer to which a signal is supplied, among the one or more electrodes of the optical element,
An optical device, wherein an angle θ between the axial direction of the conductor and the main surface of the substrate is 0 ° <θ <90 °. The optical device according to claim 1,
The optical device according to claim 1, wherein the conductor is in direct contact with the signal electrode layer. The optical device according to claim 1 or 2,
The optical device according to claim 1, wherein the conductor is connected to the signal electrode layer via a stress relief member. The optical device according to claim 1,
An optical device, wherein a feed-through substrate is interposed between the substrate and the conductor. The optical device according to any one of claims 1 to 4,
An optical device, wherein the thickness of the substrate is 30 μm or less. The optical device according to claim 5,
An optical device, wherein a support substrate is fixed to a back surface of the substrate. The optical device according to any one of claims 1 to 6,
A housing for housing the optical element and the connector,
The housing has a base and side plates,
The optical element is placed and fixed on the base via a pedestal,
An optical device, wherein a conductor of the connector is inserted through the side plate. The optical device according to claim 7,
When the optical element is mounted and fixed on the main surface of the pedestal,
The main surface of the substrate and the back surface of the substrate in the optical element are substantially parallel,
An optical device, wherein an angle between a main surface of the pedestal and a back surface of the base satisfies 0 ° <θ <90 °. The optical device according to claim 7, wherein
An optical device, wherein a part of a side surface of the substrate is in direct contact with the side wall. The optical device according to any one of claims 7 to 9,
An optical device, wherein means for controlling the impedance of the optical element is interposed between the side wall and a side surface of the substrate.

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