JPH07209560A - Optical module - Google Patents

Abstract

PURPOSE:To connect an optical semiconductor element to an optical waveguide so that a reflected light noise is small and the optical coupling loss is small. CONSTITUTION:The optical module incudes a substrate 1, machined to have an optical waveguide 2 formed on the surface and also have an end surface 3 slanted to the optical waveguide while its end part includes the end surface of the optical waveguide and an end surface 4 slanted to the end surface 3, and an optical semiconductor element 6 which has an optical waveguide 7 formed on the surface or inside; and the optical semiconductor element 6 is fixed to a heat sink 10 fixed to a sobmount 9. Then the surfaces 3 and 4 are so formed as to satisfy theta2=180 deg.-sin<-1>(n1costheta1)-theta1, where n1 is the refractive index of the substrate waveguide 2, and theta1 and theta2 are the angles between the substrate waveguide 2 and the surfaces 3 and 4; and the optical semiconductor element 6 is so positioned that theta3=sin<-1>(n1costheta1)-(90 deg.-theta1), where theta3 is the angle between the optical waveguide 7 of the optical semiconductor element 6 and the substrate waveguide 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module in which an optical semiconductor element and an optical waveguide necessary for constructing an optical circuit are connected, and is used for optical measurement, optical information processing, optical communication and the like. Can be widely used in the optical-related technology using.

[0002]

2. Description of the Related Art In recent years, the performance of optical devices such as semiconductor light emitting devices, light receiving devices, optical fibers, and optical waveguides has been dramatically improved.
The fields of optical technology such as optical measurement, optical information processing, and optical communication have been greatly developed. The optical circuit used there is ideally a crystal growth, as realized by a semiconductor IC.
Although it is desirable to make them integrally by a consistent manufacturing process such as patterning and etching, it is still technically difficult due to material mismatch, and most of them are composed of a combination of individually manufactured optical elements. It is realized by fixed connection.

In connecting and fixing such optical components,
Improvement of optical coupling efficiency and reduction of light reflection at the connection interface are important issues in realizing high quality optical circuits. Regarding an optical module in which an optical semiconductor element and an optical waveguide are connected, as an example of a conventional technique, Japanese Patent Laid-Open No. 60952/1993 is disclosed
No. "Optical semiconductor device", and its configuration is shown in FIG. 18 and FIG.
9 shows. In the figure, a semiconductor laser, which is a light-emitting element, is used as the optical semiconductor element 6, and its end face 13 and the end face 12 of the optical waveguide substrate 1 are processed at right angles to the respective optical waveguides 2. Are positioned so as to face each other in parallel, and the semiconductor laser is fixed to the waveguide substrate 1.

However, in a general optical circuit, as shown in FIG. 20, when the end face of the waveguide 2 is processed at a right angle, the reflectance of the light at the end face becomes maximum, and the reflected light 14 becomes a noise component. There is a problem that it will end up. This noise is caused by optical measurement and optical information processing that requires a high S / N ratio.
In optical communication, it often becomes a big problem.

In order to solve the problem of the reflected light noise, it is known that the reflected light can be removed from the optical circuit by obliquely processing the end face of the waveguide as shown in FIG. There is. Therefore, as shown in FIG. 22, the end portion of the waveguide substrate is often polished obliquely with respect to the waveguide, and the inclination angle θ ₁ is often selected to be θ ₁ = 86 ° to 70 °.

However, in this case, as shown in FIG. 22, the central direction of the light incident on the substrate waveguide is at an angle θ with respect to the waveguide.
_You will be inclined by _{3 at an} angle. This angle θ ₃ is obtained from Snell's law by the following equation (1).

Θ ₃ = sin ⁻¹ (n ₁ cos θ ₁ ) − (90 ° −θ ₁ ) (1) where n ₁ is the refractive index of the substrate waveguide 2. If the angle of the incident light deviates from this direction, the optical coupling efficiency decreases, and the relationship between the angular deviation Δθ and the optical coupling loss Loss in that case is that the mode field diameter of the light emitting element and the mode field diameter of the optical waveguide are almost the same. Given by the following equation (2) (Reference K. Kawano, et al., "Combinationlens metho
d for coupling a laser diode to a single-mode fiber
r ", Appl. Opt. 24, 984 (1985)).

Loss = ₁₀ log ₁₀ (exp (−π ² w _o ² Δθ ² / λ ² )) (dB) (2) where w _o is the mode field radius of the light emitting element and the substrate waveguide, and λ is the wavelength of light. Is. In order to avoid the optical coupling loss due to this angle shift, it is necessary to set the direction of the center of light emission of the semiconductor light emitting element, that is, the direction of the element waveguide, to be inclined by an angle θ _{3 with} respect to the substrate waveguide.

On the other hand, a semiconductor light emitting device is generally a rectangular parallelepiped having a size of several hundreds of μm, and as shown in FIG. 23, when the device waveguide and the substrate waveguide are aligned so as to be inclined by an angle θ ₃ , the angle When θ ₃ is large, the element collides with the substrate, so that the element cannot be brought sufficiently close to the end face of the waveguide, and there is a certain distance between the end face of the element and the end face of the waveguide. If the size of this interval is defined as z and the size of the semiconductor element is defined as L × L angles, z is given by the following equation (3) due to the geometrical relationship.

Z = 0.5 L · cot (θ ₁ −θ ₃ ) (3) In this case, the light emitted from the light emitting element spreads by the time it reaches the end face of the substrate waveguide, causing a mode field mismatch, The optical coupling loss at that time is given by the following equation (4) (Reference: Kono: Fundamentals and applications of optical coupling system for optical devices (Hyundai Engineering Co.)).

Loss = ₁₀ log ₁₀ {4 / (4 + λ ² z ² / π ² w _o ⁴ )} (dB) (4) Here, as a typical value, the wavelength of light is λ = 0.84 μ
m, the size of the semiconductor element is 300 μm square (L = 30
0 μm) and the mode field radius w _o = 1 μm,
The refractive index of the substrate waveguide is n ₁ = 2.2, and the tilt angle of the substrate is θ ₁
= 80 °, the normal incident light angle θ ₃ is calculated as θ ₃ = 12.5 ° from the equation (1). On the other hand, the distance z is
From (3), z = 62 μm is calculated. Therefore, the optical coupling loss is, from the formula (4), except the Fresnel reflection loss at the end face,
Calculated as Loss = -18 (dB).

[0012]

In principle, the optical coupling between the light emitting element and the waveguide should be such that if the mode field diameters of the two are equal, coupling can be achieved without loss except Fresnel reflection loss. It can be said that -18 (dB) is large. Generally, the greater the intensity of light propagating in the optical circuit,
Finally, since the S / N ratio at the time of detecting the signal light by the light receiving element is increased, in order to improve the performance of the optical circuit, realization of the connection method and the assembly structure for reducing the above-mentioned coupling loss becomes a problem.

An object of the present invention is to provide an optical module which can reduce the coupling loss between an optical element and an optical waveguide and which can be easily positioned and fixed.

[0014]

The above-mentioned object is to form an optical waveguide 2 on the surface, and the end portion is inclined with respect to the end face 3 and the end face 3 including the end face of the optical waveguide. It includes a substrate 1 processed to have an end surface 4 and an optical semiconductor element 6 having an optical waveguide 7 formed on the surface or inside thereof. The optical semiconductor element 6 is fixed to a submount 9 and the submount 9 is attached to a heat sink 10. The optical semiconductor element 6 is fixed, the light emitting end surface of the optical semiconductor element 6 is substantially parallel to the end surface 4 of the substrate 1, and the emitted light of the optical semiconductor element 6 enters the optical waveguide 2 of the substrate 1. This is achieved by an optical module characterized in that 6 is positioned.

In the above optical module, the substrate waveguide 2
Where n _{1 is} the refractive index of the substrate and θ ₁ and θ ₂ are the angles formed by the substrate waveguide 2 and the surfaces 3 and 4, respectively, θ ₂ = 180 ° −sin
^-1 (n ₁ cos θ ₁ ) −θ ₁ so that the surface 3
And the surface 4 are produced, and the optical waveguide 7 of the optical semiconductor element 6 is manufactured.
The angle θ ₃ between the substrate waveguide 2 and the substrate waveguide 2 is θ ₃ = sin ⁻¹ (n ₁ cos
It is preferable that the optical semiconductor element 6 is positioned so as to have a value calculated by the formula θ ₁ ) − (90 ° −θ ₁ ).

The optical semiconductor element is mounted on the submount 9,
The submount 9 may be fixed to a metal heat sink 10 by soldering, and the heat sink 10 may be fixed to the substrate 1 by a bonding material 11 to form an optical module.

Further, LiNbO ₃ is used as the material of the substrate 1, a Ti-doped waveguide is used as the substrate waveguide 2, a semiconductor laser or a super luminescent diode is used as the optical semiconductor element 6, and a surface is used as the submount 9. The back surface is made of metallized ceramics, a UV curable adhesive is used as the bonding material 11, and the angle θ _{1 is set} to 80.
The optical module may be configured such that the angle θ, the angle θ ₂ are 77.5 °, and the angle θ ₃ is 12.5 °.

As another solution, the optical waveguide 2 is formed on the surface.
And a substrate 1 processed to have an end face 3 including an optical entrance 24 of the optical waveguide and an end face 3 inclined with respect to the waveguide and an end face 4 inclined with respect to the end face, and a surface or A light emitting element 6 in which a waveguide 7 is formed, a base 26 for mounting the substrate 1, and a heat sink 10 for mounting the light emitting element 6 are included, and the refractive index of the substrate waveguide 2 is n ₁ ,
When the angles formed by the substrate waveguide 2 and the surfaces 3 and 4 are θ ₁ and θ ₂ , respectively, 0 <θ ₂ ≦ 180 ° −sin ⁻¹ (n ₁ cos
Surfaces 3 and 4 are formed so as to satisfy the formula θ ₁ ) −θ ₁ , the light emitting element 6 is fixed to the submount 9, the submount 9 is fixed to the heat sink 10, and the base 2
The substrate 1 is fixed on the optical waveguide 6 and the optical waveguide 2 is connected to the optical waveguide 7 of the light emitting element 6 by θ ₃ = sin ⁻¹ (n ₁ cos θ ₁ ) − (90 °
Angle θ ₃ given by −θ ₁ ), and the light entrance 24 of the optical waveguide 2 is positioned near the light exit 25 of the light emitting element waveguide 7, and the light emitted from the light emitting element 6 is The heat sink 10 is placed on the base 2 so as to enter the substrate waveguide 2.
6 is fixed to the side surface 29 of the optical module 6.

In this case, the light receiving element submount 38 is fixed on the heat sink 10 behind the light emitting element 6, and the light receiving element 37 is fixed to the submount 38 at a position where the backward light emitted by the light emitting element 6 can be detected. May be.

The substrate 1 is made of LiNbO ₃ , the substrate waveguide 2 is a Ti-doped waveguide, the light emitting device 6 is a semiconductor light emitting device such as a semiconductor laser or a super luminescent diode, and the submount 9 is used. Ceramics can be used as the base 26, iron can be used as the base 26, iron, Kovar or copper tungsten can be used as the heat sink 10, and a photodiode can be used as the light receiving element 37.

Further, the optical gyro system can be constructed by including the optical module in the optical system.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a top view showing an optical module according to the invention. In FIG. 1, reference numeral 1 denotes a substrate having a substrate waveguide 2 formed on its surface, the end portion of which includes the end face of the substrate waveguide 2 and an end face 3 which is inclined with respect to the waveguide 2 and further inclined with respect to the end face 3. It is processed so as to have a curved end surface 4. Reference numeral 6 denotes an optical semiconductor element having an element waveguide 7 formed on the surface or inside thereof, which is soldered and fixed to a submount 9, and the submount 9 is further soldered and fixed to a metal heat sink 10. The light emitting end surface of the optical semiconductor element 6 is substantially parallel to the end surface 4 of the substrate 1, and the optical semiconductor element 6 is positioned so that the light emitted from the element waveguide 7 enters the substrate waveguide 2.
It is fixed by 1. The difference between FIGS. 1A and 1B lies in the use of the bonding material 11, and in FIG.
While the bonding material is adhered and fixed only on the sliding surface between the end face 4 of the substrate and the heat sink 10 including the optical semiconductor element 6, in (b), the substrate including the gap between the substrate waveguide 2 and the element waveguide 7 is included. The bonding material is widely attached, filled, and fixed up to the portion extending over the end surface 3 of the first embodiment.

As mentioned above, the conventional problems are
It occurred because the optical element collided with the end surface of the substrate that was processed obliquely. In order to avoid the collision, as shown in FIG. 2, the corner of the end portion 3 of the substrate 1 is shaved to form a new surface 4, and the surface 4 is polished until the end of the surface 4 approaches the vicinity of the substrate waveguide 2. did. In this case, the angle θ ₂ formed by the surface 4 and the substrate waveguide 2 is expressed by the following equation (5) θ ₂ = 90 ° −θ ₃ = 180 ° −sin ⁻¹ (n ₁ ) with respect to the light incident angle θ ₃ . cos θ ₁ ) −θ ₁
The value is determined by (5). Then, as shown in FIG. 1, the heat sink 10 is slid on the surface 4 to position and fix the optical semiconductor element 6.

When the connection method as described above is adopted, the optical element waveguide 7 and the substrate waveguide 2 can be sufficiently close to each other so that the optical semiconductor element 6 and the waveguide substrate 1 do not collide with each other.
Then, if the heat sink 10 is slidably fixed to the surface 4 of the substrate 1, the optical element waveguide 7 can be automatically aligned in the correct incident direction. As a result, since the optical connection between the optical element waveguide 7 and the substrate waveguide 2 can be realized with a small gap and no angular deviation, the optical coupling loss can be reduced.

Next, an embodiment of the connection method of the present invention will be described with reference to FIGS. In FIG. 3, LiNbO ₃ is used as the waveguide substrate 1, and the waveguide 2 is formed on the surface by Ti doping. The tilt angle θ ₁ is selected to be 80 °, the tilt angle θ ₂ is calculated as 77.5 ° by the formula (5), and the incident angle θ ₃ is calculated as 12.5 ° by the formula (1). The parts were polished to form end faces 3 and 4. However, when polishing the end face 4, the polishing was controlled so that the end of the end face 4 was located at a distance of 50 μm from the end of the waveguide so as not to reach the end face of the waveguide 2. The wavelength of the optical semiconductor element 6 is 0.84μ
Although an m 2 semiconductor laser is used, it is also possible to use a super luminescent diode. The semiconductor laser 6 is a ceramic submount 9 whose surface is plated with gold.
The submount 9 is soldered to a metal heat sink 10. At the time of connection, the substrate 1 is fixed to the fixed base 16, the heat sink 10 on which the semiconductor laser 6 is mounted is attached to the fine movement stage 21, and the semiconductor laser 6 can be finely moved three-dimensionally. A TV camera 17 for monitoring is installed in the rear. Then, when the semiconductor laser 6 is slightly moved by the stage 21 while emitting light, the emitted light 18 is observed by the monitor camera 17 when the light enters the substrate waveguide 2, so that the light intensity seen by the monitor CRT 19 is maximized. The stage 21 is positioned.

Next, in order to perform fine adjustment, as shown in FIG. 4, a monitor fiber 20 connected to another fine movement stage 21 is installed on the substrate output side. A PD (photodetector) 22 is installed at the opposite end of the fiber, and if light is input to the fiber, it can be detected by the PD. PD detection light 2
After the monitor fiber 20 is once positioned at the position where 3 is the maximum, both the semiconductor laser 6 and the fiber 20 are finely adjusted, and both are finally positioned at the position where the PD detection light 23 is maximized. Fixed with Agent 11. In an actual system, the distance z between the element waveguide 7 and the substrate waveguide 2 is about 20.
μm, and the coupling loss Loss calculated from equation (4) is -9
It was (dB). Therefore, the coupling loss can be improved by 9 (dB) from -18 (dB) in the case of the conventional technique.

In the above-described embodiment, the heat sink 10 is directly fixed to the waveguide substrate 1 as shown in FIG. However, in this case, since the heat sink 10 is not fixed on the entire surface, cracks are likely to occur due to environmental changes such as temperature cycles, and long-term reliability is not always sufficient. Therefore, in another embodiment, as shown in FIG. 5, a plate-shaped base 26 is separately manufactured, and the base 26 is manufactured.
The substrate 1 is placed on the substrate 2, the light incident port 24 of the substrate waveguide 2 is as close as possible to the ridgeline 30 of the connection surface 29 of the base 26, and the waveguide 2 is in relation to the normal 31 of the connection surface 29 by the above formula (1) Substrate 1 is base 2 in a positional relationship that forms an angle θ ₃ given by
6 is fixed, and the connection surface of the heat sink 10 is slidably fixed to the connection surface 29 of the base 26.
The optical semiconductor element 6 is fixed on the heat sink 10 in such a positional relationship that the light emitting port 25 thereof is sufficiently close to the light incident port 24 of the substrate waveguide 2.

As described above, the structure in which the substrate 1 is placed on the base 26 and the heat sink 10 and the base 26 are slid on each other and fixed to the entire surface is more reliable and superior.

Also in this embodiment, as in the previous embodiment, the light emitting device 6 and the waveguide substrate 1 do not collide with each other while the device waveguide 7 and the substrate waveguide 2 form an angle θ _3. Since the light output port 25 of the waveguide 7 and the light input port 24 of the substrate waveguide 2 can be brought sufficiently close to each other, the optical connection between the optical element waveguide 7 and the substrate waveguide 2 has a small gap and a small gap. As a result, it goes without saying that the optical coupling loss can be reduced.

Hereinafter, another embodiment of the present invention will be described in more detail with reference to FIGS.

First, in FIG. 6, L is used as the waveguide substrate 1.
Using iNbO ₃ , a bifurcated (Y-branched) waveguide 2 is formed on the surface by Ti doping, and the refractive index of the waveguide is changed by changing the voltage so that the propagation light in the waveguide can be controlled. An optical IC was formed by providing an electrode 28 for this purpose. The inclination angle θ ₁ is selected to be 80 °, and the normal incident light angle θ ₃ to the waveguide in that case is 12.5 ° from the formula (1).
Is calculated. As the tilt angle θ ₂ , an upper limit value of 77.5 ° obtained as a result of calculation by the formula (5) or a value several degrees smaller than this is used in consideration of safety. Then, the end portions of the substrate 1 were polished so as to realize these inclination angles θ ₁ and θ ₂ , and the end surfaces 3 and 4 were formed. In order to reduce the above-mentioned interval z, the end 57 of the end face 4 should be as close as possible to the light entrance port 2 of the waveguide 2.
Although it should be close to 4, the polishing was controlled so that the end 57 of the end face 4 was located at a distance of 50 μm from the entrance 24 from the limit of processing accuracy.

For the base 26, iron (coefficient of linear expansion: 11 × 10 ⁻⁶ / ° C.) having a coefficient of linear expansion close to that of LiNbO ₃ (coefficient of linear expansion in the longitudinal direction: 14.1 × 10 ⁻⁶ / ° C.) is used. As a material, for convenience of mounting, the top view as shown in FIG. 7 has a parallelogram-shaped outer shape, and the reference ridge line 32 forms an angle θ ₃ with the normal 31 of the connection surface 29. Processed as follows.

In assembly, as shown in FIG. 8, first, a thin plate-shaped electronic circuit board 34 for electrically driving the optical IC 1 was fixed to the groove 33 of the base 26 with an adhesive. Next, the optical IC 1 was placed on the base so that the entrance 24 of the waveguide 2 was brought as close as possible to the ridgeline 30 of the connection surface 29 of the base 26. At the same time, the waveguide 2 or the side surface 5 of the optical IC parallel to the waveguide 2
When 8 is aligned so as to be parallel to the reference ridgeline 32 on the base 26, the waveguide 2 automatically forms an angle θ ₃ with respect to the normal 31 of the connection surface 29 of the base 26 from the shape of the base 26. Therefore, the back surface of the optical IC 1 was fixed to the base 26 with an adhesive at this position. For fixing in this case, a UV curable adhesive that can be cured by UV irradiation after positioning is convenient. And
The electrical wiring between the optical IC 1 and the circuit board 34 was performed by the bonding wire 36.

On the other hand, in the light source section shown in FIG. 9, a semiconductor laser having a wavelength of 0.84 μm or 0.78 μm is used as the optical semiconductor element 6, but another type of semiconductor light emitting element such as a super luminescent diode is used. Is also possible. As the material of the heat sink 10, the same iron as the base 26, or Kovar (coefficient of linear expansion: 5.3 × 10 ⁻⁶ / ° C.) or copper-tungsten (coefficient of linear expansion: to reduce the effect of thermal expansion and contraction). A material having a small linear expansion coefficient such as 6.0 × 10 ⁻⁶ / ° C.) was used. The semiconductor laser 6 is soldered to a ceramic submount 9 whose surface is plated with gold, and the submount 9 is soldered to a metal heat sink 10. However, the positional relationship is that the light emitting port 25 of the semiconductor laser 6 is a heat sink. The laser waveguide 7 is arranged so as to be substantially on the same plane as the connection surface 39 of 10 and perpendicular to the connection surface 39. A photodiode (PD) 37 was used for monitoring the backward emission light of the semiconductor laser 6, and was soldered to the submount 38. Submount 3
8 is a photodiode (PD) 37 as a light receiving element
However, it is positioned and fixed on the heat sink 10 so as to be positioned behind the semiconductor laser 6.

The light source unit manufactured in this manner is used as an optical IC.
As shown in FIG. 10, when the surface 39 of the heat sink 10 is slid on the surface 29 of the base in order to optically couple to the optical waveguide 1, the angle between the element waveguide 7 and the substrate waveguide 2 is automatically set to the above-mentioned design value. θ ₃ = 12.5 °. At the time of connecting and fixing, the base 26 is fixed to the fixing base 62, and the heat sink 10
Is mounted on a fine movement stage 21 so that the semiconductor laser 6 can be finely moved three-dimensionally, and a TV camera 17 for monitoring is installed behind the output side of the substrate waveguide 2. When the stage 21 is slightly moved while the semiconductor laser 6 is emitting light, the emitted light 18 is observed by the monitor TV camera 17 if the light enters the substrate waveguide 2, so that the monitor CRT 1
The stage 21 is positioned so that the light intensity seen at 9 is maximum.

Next, for fine adjustment, as shown in FIG. 11, a monitor fiber 20 connected to another fine movement stage 21 is installed on the light output side of the optical IC 1. A photodetector 22 is installed at the opposite end of the fiber, and when light is input to the fiber, the output light 23 can be detected by the photodetector. After the monitor fiber 20 is once positioned at a position where the output light 23 becomes maximum, the semiconductor laser 6
The optical module is obtained by finely adjusting both the fiber 20 and the fiber 20, and finally fixing the heat sink 10 and the base 26 with the adhesive 11 at a position where the output light 23 is maximized. In an actual manufacturing example, the element waveguide 7 and the substrate waveguide 2
The distance z was about 20 μm, and the coupling loss Loss calculated from the equation (4) was −9 (dB). Therefore, the coupling loss could be improved from -18 (dB) to 9 (dB).

In the above example, a rectangular heat sink is used, but the light source module that is generally commercially available is shown in FIG.
In many products, a columnar heat sink 10 is erected on a disc-shaped stem 40 as shown in FIG. 2, and the light emitting element 6 and the light receiving element 37 are fixed thereon. In order to reduce the manufacturing cost, it may be better to directly use such a mass-produced product as a light source component. In that case,
As shown in FIGS. 13 and 14, a hollow cylindrical tube 42 may be manufactured, the bottom surface thereof may be fixed to the upper surface of the light source stem 40, and the upper surface may be fixed to the base. However, in this case, in order to minimize the distance z between the light emitting element exit port and the substrate waveguide entrance port to improve the optical coupling efficiency, the length h _{1 of the} tube is set to the stem 40.
Was processed so as to substantially match the distance h ₂ from the upper surface of the light emitting element to the light emitting element emission port 25. In addition, the rectangular cutout window 45 formed on the side surface of the cylinder 42 has the light emitting element 6 and the substrate waveguide 2.
It is provided in order to facilitate the alignment by making the light emitting element 6 visible when performing the alignment.

According to the steps described above, the light emitting device and the light I
An optical module in which C is coupled is obtained. In particular, in this embodiment, a gyro chip used in an optical gyro system was used as the optical IC for manufacturing. A typical configuration example of an optical fiber gyro is shown in Fig. 15 (references: Kajioka, Kumagai, Oho, "Interference type optical fiber gyro", OPTR).
ONICS, No. 5, 127 (1990)). In this configuration example, if the photodetector 54 used for detecting the signal light returning from the gyro chip is also used as the monitoring photodiode 47 of the light source, the number of parts can be reduced, and a configuration example of the gyro in that case is shown. 16 shows.

A gyro chip is obtained by integrating the polarizer 50, the coupler 51, and the phase modulator 52 in FIG. 15 or 16 into an optical IC, which is a two-branch (Y-branch) as shown in the above embodiment. A waveguide is formed on the surface, and electrodes for electrical control are provided on the surface. On the other hand, the light source and the photodiode integrated on the heat sink correspond to the light source section described in the above embodiment. Then, as shown in FIG. 17, after assembling the light source unit and the gyro chip according to the above steps, the optical fibers 60 at both ends of the optical fiber loop 53 are aligned and fixed to the light emitting ports 59 of the gyro chip 1, The optical fiber gyro is completed as a whole. Reference numeral 61 is a holder for holding the end portion of the optical fiber 60.

In the above process, an adhesive is used for fixing the electronic circuit board 34 and the base 26, fixing the optical IC 1 and the base 26, and fixing the heat sink 10 and the base 26 because it is easy to use. To increase sex,
Replacing with solder fixing is effective. In that case, solder fixing can be performed by performing metallization treatment such as gold plating or nickel plating on each connection surface. Further, in the case of fixing metal materials to each other like fixing the heat sink 10 and the base 26, welding and fixing by YAG welding, resistance welding or the like is also possible. In this case, higher strength than solder fixing can be obtained. The reliability can be increased.

In the optical module of this embodiment, the distance between the optical element exit port and the optical waveguide entrance port can be reduced in a state where the light exit direction of the optical device is aligned with the light entrance direction of the optical waveguide, so that high optical coupling is achieved. It is highly efficient and has excellent reliability because the heat sink can be fixed to the entire surface of the base.

[0042]

According to the present invention, the optical element waveguide and the substrate waveguide can be sufficiently close to each other so that the optical semiconductor element and the waveguide substrate do not collide with each other. Then, if the heat sink is fixed by sliding on the surface of the substrate, the optical element waveguide can be automatically aligned in the correct incident direction. As a result, since the optical connection between the optical element waveguide and the substrate waveguide can be realized with a small gap and no angular deviation, the optical coupling loss can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an optical module that is an embodiment of the present invention.

FIG. 2 is an explanatory view showing a structure for solving a problem at the time of connecting an optical semiconductor element and an optical waveguide in an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a method of connecting an optical semiconductor element and an optical waveguide.

FIG. 4 is an explanatory diagram showing a method for connecting an optical semiconductor element and an optical waveguide.

FIG. 5 is an explanatory diagram showing an optical module that is another embodiment of the present invention.

FIG. 6 is an explanatory diagram of a waveguide substrate (optical IC) used in another embodiment of the present invention.

FIG. 7 is an explanatory view of a base used in the embodiment.

FIG. 8 is an assembly diagram of a waveguide substrate (optical IC), a circuit substrate, and a base in the embodiment.

FIG. 9 is an assembly explanatory diagram of a semiconductor light emitting element / light receiving element in the embodiment.

FIG. 10 is an explanatory view showing a method of connecting and fixing the light source unit and the base.

FIG. 11 is an explanatory diagram showing a method of connecting and fixing the light source unit and the base.

FIG. 12 is a schematic view of a mass production type light source module.

FIG. 13 is an assembly explanatory diagram of a mass production type light source module and a tube.

FIG. 14 is an explanatory view showing a method of connecting and fixing the mass production type light source module and the base.

FIG. 15 is a configuration diagram of a general optical fiber gyro.

FIG. 16 is an explanatory diagram of an optical fiber gyro that is also used for signal light detection by a monitor photodiode.

FIG. 17 is an explanatory diagram of an optical gyro system using an optical module according to another embodiment of the present invention.

FIG. 18 is an explanatory diagram of a conventional technique.

FIG. 19 is an explanatory diagram of a conventional technique.

FIG. 20 is an explanatory diagram of reflected light on a vertical end face of a waveguide.

FIG. 21 is an explanatory view of removing reflected light by obliquely polishing the end portion of the waveguide.

FIG. 22 is an explanatory view of an incident light angle by obliquely polishing the end of the waveguide.

FIG. 23 is an explanatory diagram showing a problem when connecting an optical element and an optical waveguide.

[Explanation of symbols]

 1 Waveguide Substrate 2 Optical Waveguide 3 Substrate End Face Including Waveguide Entrance 4 Substrate End Face Not Including Waveguide Entrance 5 Optical Waveguide Centerline 6 Optical Semiconductor Device 7 Element Waveguide 8 Element Waveguide Centerline 9 Submount 10 Heat Sink 11 Joining Material 12 Optical Waveguide End Face of Conventional Device 13 Optical Semiconductor Element End Face of Conventional Device 14 Reflected Light at Waveguide End Face 15 Incident Light to Waveguide End Face 16 Fixing Stand 17 Monitor TV Camera 18 Waveguide Output End Output Emitting light 19 Monitor CRT 20 Monitor fiber 21 Fine movement stage 22 PD (photodetector) 23 Output light 24 Light entrance port of optical waveguide 25 Light exit port of element waveguide 26 Base 27 Two-branch (Y branch) waveguide 28 Electrode 29 Side of base (Connection surface) 30 Ridge line of connection surface 31 Normal line of connection surface 32 Reference ridge line 33 Groove 34 Electronic circuit board 5 Electrode 36 Bonding Wire 37 Light-Receiving Element 38 Light-Receiving Element Submount 39 Heat Sink Connection Surface 40 Stem 41 Lead 42 Cylinder 44 Bonding Material (Adhesive) 45 Cutout Window 46 Light Source 47 Monitor Photodiode 48 Optical Fiber 49 Coupler 50 Polarizer 51 Coupler 52 Phase Modulator 53 Optical Fiber Loop 54 PD 55 Backward Emitted Light of Semiconductor Light Emitting Device 56 Signal Light 57 End of End Face 58 Side Surface of Waveguide Substrate (Optical IC) 59 Optical Emission Port of Optical IC 60 Optical Fiber 61 Holder

Front page continuation (72) Inventor Tetsuo Kumazawa 502 Jinritsucho, Tsuchiura-shi, Ibaraki Machinery Research Institute, Hiritsu Manufacturing Co., Ltd. Hidaka Plant Co., Ltd. (72) Inventor Toshio Iizuka 5-1-1 Hidaka Town, Hitachi City, Ibaraki Prefecture Hitachi Cable Ltd. Hidaka Plant

Claims (10)

[Claims] 1. An optical waveguide 2 is formed on a surface, and an end portion is processed to have an end face 3 including the end face of the optical waveguide and an end face 3 inclined with respect to the optical waveguide and an end face 4 inclined with respect to the end face 3. Substrate 1 and an optical semiconductor element 6 having an optical waveguide 7 formed on the surface or inside thereof, the optical semiconductor element 6 is fixed to a submount 9, and the submount 9 is fixed to a heat sink 10. The light emitting end face of 6 is substantially parallel to the end face 4 of the substrate 1, and the optical semiconductor device 6 is positioned so that the emitted light of the optical semiconductor device 6 enters the optical waveguide 2 of the substrate 1. Optical module. 2. The refractive index of the substrate waveguide 2 is n ₁ and the angle formed by the substrate waveguide 2 and the surfaces 3 and 4 is θ ₁ , respectively.
When θ ₂ is set, θ ₂ = 180 ° −sin ⁻¹ (n ₁ cos
The surface 3 and the surface 4 are formed so as to satisfy the formula of θ ₁ ) −θ ₁ , and the angle θ ₃ formed by the optical waveguide 7 of the optical semiconductor element 6 and the substrate waveguide 2 is θ ₃ = sin ⁻¹ (n ₁ cos θ ₁ )-(9
An optical module in which the optical semiconductor element 6 is positioned so as to have a value calculated by the formula of 0 ° -θ ₁ ). 3. The optical semiconductor device 6 according to claim 1 or 2, wherein the optical semiconductor element 6 is soldered and fixed to a submount 9, the submount 9 is soldered and fixed to a metal heat sink 10, and the heat sink 10 is bonded by a bonding material 11. An optical module fixed on a substrate 1. 4. The material of substrate 1 according to claim 3,
iNbO ₃ is used, a Ti-doped waveguide is used as the substrate waveguide 2, a semiconductor laser or a super luminescent diode is used as the optical semiconductor element 6, and a ceramic whose front and back surfaces are metallized is used as the submount 9. A UV curable adhesive is used as 11, and the angle θ ₁ is 80 °, the angle θ ₂ is 77.5 °, and the angle θ ₃ is 1.
An optical module characterized by being set at 2.5 °. 5. An optical waveguide 2 is formed on a surface, and an end portion includes an end face 3 including a light entrance 24 of the optical waveguide and an end face 3 inclined with respect to the waveguide and an end face 4 inclined with respect to the end face 3. A substrate 1 processed into the above, a light emitting element 6 having a waveguide 7 formed on the surface or inside thereof, a base 26 for mounting the substrate 1 thereon,
Including a heat sink 10 for mounting the light emitting element 6,
The refractive index of the substrate waveguide 2 is n ₁ , the substrate waveguide 2 and the surfaces 3, 4 are
When the angles formed by are θ ₁ and θ ₂ , respectively, 0 <θ ₂ ≦ 1
Surfaces 3 and 4 are formed so as to satisfy the expression 80 ° -sin ^-1 (n ₁ cos θ ₁ ) -θ ₁ , and the light emitting element 6 is fixed to the submount 9 and the submount 9 is fixed to the heat sink 10. It is fixed, the substrate 1 is fixed on the base 26, and the optical waveguide 2 is connected to the optical waveguide 7 of the light emitting element 6 and θ ₃ = sin.
^-1 (n ₁ cos θ ₁ ) − (90 ° −θ ₁ )
Form a _third angle, and the light entrance 24 of the optical waveguide 2 are positioned in the vicinity of the light exit opening 25 of the light emitting element waveguide 7 so that the light emitted from the light emitting element 6 is incident on the substrate waveguide 2 An optical module in which the heat sink 10 is fixed to the side surface 29 of the base 26. 6. The sub-mount 38 for a light-receiving element is fixed to the rear of the light-emitting element 6 on the heat sink 10 according to claim 5, and the light-receiving element 37 is located at a position where the rear light emitted from the light-emitting element 6 can be detected. An optical module characterized by being fixed to 38. 7. The material for a substrate 1 according to claim 5,
iNbO ₃ is used, a Ti-doped waveguide is used as the substrate waveguide 2, a semiconductor light emitting element such as a semiconductor laser or a super luminescent diode is used as the light emitting element 6, a ceramic is used as the submount 9, and the base 2 is used.
An optical module characterized in that iron is used as 6 and iron, kovar, or copper tungsten is used as the heat sink 10. 8. The L as a material of the substrate 1 according to claim 6.
iNbO ₃ is used, a Ti-doped waveguide is used as the substrate waveguide 2, a semiconductor light emitting element such as a semiconductor laser or a super luminescent diode is used as the light emitting element 6, and a light emitting element submount 9 and a light receiving element submount are used. Ceramic is used as 38, a photodiode is used as the light receiving element 37, and iron is used as the base 26.
An optical module using iron, kovar, or copper tungsten as the heat sink 10. 9. An optical gyro system including the optical module of claim 6 in an optical system. 10. An optical gyro system including the optical module of claim 8 in an optical system.