JP2009192953A - Optical function element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical function element which has small stray light to have excellent noise characteristics, and is easy to manufacture. <P>SOLUTION: The optical function element includes a light emitting element 12 as a light source, a dielectric substrate 14 having an optical waveguide 20 formed, and a light receiving element 16 which converts light into electricity, wherein light from the light emitting element 12 is modulated with an external electric signal and the modulated light is output in the form of an electric signal through the light receiving element 16. The optical waveguide 20 includes an input waveguide portion 20a formed on a surface 14a of the dielectric substrate 14, modulation portions 20b and 20c which branch off from the input waveguide portion 20a and are modulated with the external electric signal, and an output waveguide portion 20d connecting with the modulation portions. The light emitting element 12 and light receiving element 16 are disposed on the side of the reverse surface 14b of the dielectric substrate 14, and emit and receive light beams in a direction orthogonal to the top surface 14a and reverse surface 14b, respectively. Mirrors 26 and 28 are provided at a starting end of the input waveguide portion 20a and at an ending end of the output waveguide portion 20d. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention includes a light-emitting element as a light source, a dielectric substrate on which an optical waveguide is formed, and a light-receiving element that converts light into electricity, and modulates the light from the light source with an external electric signal and modulates the light The present invention relates to an optical functional element that outputs the emitted light as an electrical signal by a light receiving element.

  Conventionally, as optical functional elements having this type of modulation function, those described in Patent Document 1 or 2 are known, and the configuration described in these Patent Documents is generally as shown in FIG. Yes.

  In the figure, 112 is a light emitting element as a light source, 114 is a dielectric substrate, 116 is a light receiving element, an optical waveguide 120 is formed on the dielectric substrate 114, and the optical waveguide 120 is, for example, a Mach-Zehnder type An optical interferometer is configured, and the light emitting element 112 and the light receiving element 116 are disposed so as to face both sides of the optical waveguide 120.

  The light output from the light emitting element 112 is collected by the condenser lens 122 and is incident on one end of the optical waveguide 120 from the end face of the dielectric substrate 114. In the optical waveguide 120, the light modulated by the external electric signal is emitted from the other end of the optical waveguide 120, collected by the condenser lens 124, and received by the light receiving element 116.

JP-A-6-27427 JP 2003-131182 A

  However, in the optical functional element having the above-described conventional configuration, since the light emitting element and the light receiving element which are light sources are opposed to each other, there is a problem that there is a lot of stray light and the noise characteristics deteriorate.

  Furthermore, since light is incident from the end face of the dielectric substrate, after the dicing operation of the original wafer of the dielectric substrate, it is necessary to polish the end face which is a cutting surface, which is troublesome. There is.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical functional element that has less noise and has good noise characteristics and is easy to manufacture.

In order to solve the above-described problems, the present invention includes a light emitting element as a light source, a dielectric substrate on which an optical waveguide is formed, and a light receiving element that converts light into electricity, and the light from the light emitting element. In an optical functional element that modulates an external electrical signal and outputs the modulated light as an electrical signal by the light receiving element,
The optical waveguide includes an input waveguide portion formed on a plane parallel to the plate surface of the dielectric substrate, a modulation portion connected to the input waveguide portion and modulated by the external electric signal, and the modulation portion And an output waveguide portion connected to
The light emitting element emits light toward a start end of the input waveguide portion along a direction orthogonal to the plane.
The start end of the input waveguide portion is provided with a turning means for directing light from a direction orthogonal to the plane to the input waveguide portion.

According to a second aspect of the present invention, the second turning means for directing light propagating through the output waveguide portion in a direction perpendicular to the plane is provided at the end of the output waveguide portion according to the first aspect. ,
The light receiving element receives a light which is redirected by a second deflecting unit and propagates in a direction orthogonal to the plane.

  A third aspect of the present invention is characterized in that the plane according to the first or second aspect is the surface of the dielectric substrate, and the light emitting element is disposed on the back side of the dielectric substrate.

  According to a fourth aspect of the present invention, the light receiving element according to the third aspect is arranged on the back side of the dielectric substrate.

  The invention according to claim 5 is characterized in that the light receiving element according to claim 3 is arranged on the surface side of the dielectric substrate.

  The invention according to claim 6 is characterized in that the plane according to claim 1 or 2 is a surface of the dielectric substrate, and the light emitting element and the light receiving element are arranged on a surface side of the dielectric substrate. To do.

  According to a seventh aspect of the present invention, the distance and direction from the starting end of the input waveguide portion are known in the vicinity of the starting end of the input waveguide portion of the dielectric substrate according to any one of the first to sixth aspects. A marker for matching the light spot from the light emitting element during adjustment is formed.

  According to an eighth aspect of the present invention, a conductive pattern is formed on both sides of the optical waveguide on the plane according to any one of the first to seventh aspects, and the conductive pattern is formed by a conductive member. It is connected.

  A ninth aspect of the invention is characterized in that a conductive material that is electrically connected to the conductive pattern is applied to a side surface of the dielectric substrate according to the eighth aspect.

  According to the present invention, the direction of the light emitted from the light emitting element is different from the direction of the light propagating through the optical waveguide, and the light emitting element and the light receiving element can be prevented from facing each other, thereby reducing stray light. Noise characteristics can be improved. Further, since it is not necessary to use the end face of the dielectric substrate as the incident face, it is possible to eliminate the end face polishing work.

  According to the second aspect of the present invention, it is possible to prevent the direction of the light emitted from the light emitting element, the direction of the light propagating through the optical waveguide, and the direction of the light received by the light receiving element from being all aligned. , Stray light can be more reliably reduced.

  According to the third aspect of the present invention, since the position of the light spot from the light emitting element on the back surface side can be visually grasped as the position in the surface of the dielectric substrate, the position of the light spot is the input guide. By aligning with the start end of the waveguide portion, the position of the light emitting element can be easily adjusted.

  According to the fourth aspect of the present invention, the direction of the light emitted from the light emitting element, the direction of the light propagating through the optical waveguide, and the direction of the light received by the light receiving element are not all aligned but are directed in different directions. Therefore, stray light can be more reliably reduced.

  According to the fifth aspect of the present invention, it is possible to prevent the direction of the light emitted from the light emitting element, the direction of the light propagating through the optical waveguide, and the direction of the light received by the light receiving element from being all aligned. , Stray light can be more reliably reduced.

  According to the sixth aspect of the present invention, the direction of the light emitted from the light emitting element, the direction of the light propagating through the optical waveguide, and the direction of the light received by the light receiving element are not all aligned but are directed in different directions. Therefore, stray light can be more reliably reduced. Furthermore, since the light emitting element and the light receiving element are disposed on the front surface side, the planar substrate can be formed as a whole together with the dielectric substrate, which facilitates handling.

  According to the seventh aspect of the present invention, the light spot from the light emitting element is adjusted by monitoring so that the light spot from the light emitting element coincides with the marker, and is further moved to a known distance and direction from the marker to It can be coincident with the beginning of the input waveguide portion.

  According to the eighth and ninth aspects of the present invention, the conductive patterns formed on both sides of the dielectric substrate are connected, so that the pattern is generated in a direction parallel to the plane and perpendicular to the optical waveguide of the dielectric substrate. It is possible to prevent the thermoelectromotive force (pyroelectric effect) that may occur.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is an overall perspective view of the optical functional element of the present invention, FIG. 2 is a cutaway perspective view thereof, FIG. 3 is a plan view thereof, and FIG. 4 is a longitudinal sectional view thereof.

  In the figure, an optical functional element 10 includes a light emitting element 12 as a light source, a dielectric substrate 14 on which an optical waveguide is formed, and a light receiving element 16 that converts light into electricity.

  As the light emitting element 12, a light emitting diode or a laser can be used. Among them, a super luminescent diode, a surface emitting laser, or the like can be used. As the light receiving element 16, a photodiode can be used.

  The dielectric substrate 14 is made of a dielectric crystal having an electro-optic effect, such as lithium niobate, and has an x cut width of about 5 μm by titanium diffusion or annealed proton exchange along the y-axis direction on the surface 14a. The single mode optical waveguide 20 is formed.

  The optical waveguide 20 has one linear input waveguide portion 20a formed on a surface 14a which is a plane parallel to the plate surface of the dielectric substrate 14, and 2 separated from the input waveguide portion 20a by a Y branch. It consists of two branched waveguide portions 20b and 20c and one linear output waveguide portion 20d in which the two branched waveguide portions 20b and 20c are joined by a Y branch.

  The two branched waveguide portions 20b and 20c constitute a modulation portion, and are formed so that their lengths are different by about λ / 4 (λ is a wavelength within the waveguide of light to be used). A pair of electrodes 22 and 24 are formed with each branching waveguide portion 20b and 20c interposed therebetween.

  On the surface 14a of the dielectric substrate 14, a V-shaped cut 14c having a slope having a slope of 45 degrees with respect to the surface 14a is formed so as to be orthogonal to the input waveguide portion 20a of the optical waveguide 20. Then, a V-shaped cut 14d having a slope having an inclination angle of 45 degrees with respect to the surface 14a is formed so as to be orthogonal to the output waveguide portion 20d. The cuts 14c and 14d can be collectively formed over the plurality of dielectric substrates 14 by a dicing operation on the wafer before being cut out as the dielectric substrate 14.

  As shown in FIG. 5, a reflective film is attached to the inclined surface having the inclination angle of 45 degrees on the side in contact with the input waveguide portion 20a of the V-shaped cut 14c (becoming the starting end of the input waveguide portion 20a). , The mirror 26 constituting the turning means is formed. Similarly, a reflective film is attached to the inclined surface having an inclination angle of 45 degrees on the side in contact with the output waveguide portion 20d of the V-shaped cut 14d (which is the terminal end of the output waveguide portion 20d), so that the second turning direction is obtained. A mirror 28 constituting the means is formed. Each reflective film can be formed by gold vapor deposition, and after the reflective film is formed, the V-shaped notch is filled with a material having a refractive index equal to or similar to that of the dielectric substrate 14. Good. However, this filling material is not shown in the drawing. The mirrors 26 and 28 as the deflecting means may be constituted by micromirrors inserted into 45-degree inclined grooves as shown in FIG. Alternatively, when there is a large reflectance at the inclined surfaces themselves of the end portions of the optical waveguide portions 20a and 20d, a means such as a separate reflecting film can be omitted by using it as a turning means.

An antireflection film (AR coating) is preferably attached to the entire surface of the back surface 14b of the dielectric substrate 14. The antireflection film can be composed of a SiO ₂ or TiO ₂ film, and this film can be formed in a lump on the wafer before being cut out as the dielectric substrate 14.

  A mounting plate 30 for supporting the light emitting element 12 and the light receiving element 16 is provided on the back side of the dielectric substrate 14. The mounting plate 30 can be made of ceramic or metal with good heat dissipation. As shown in FIG. 4, the mounting plate 30 is formed with vertical holes 30a and 30b whose longitudinal directions coincide with the notches 14c and 14d.

  The cylindrical hole 32 made of, for example, metal having high rigidity, which holds the light emitting element 12 and is fixed to the dielectric substrate 14, is attached to the vertical hole 30a. A flange 32 a is formed at the upper end of the cylindrical holder 32, and the flange 32 a is attached to the lower surface of the dielectric substrate 14 and fixed to the dielectric substrate 14.

  As shown in FIGS. 7 and 8, an annular groove 32b is formed on a part of the surface of the flange 32a. The annular groove 32b is filled with an ultraviolet curable resin, and the ultraviolet curable resin is bonded thereto. The cylindrical holder 32 and the dielectric substrate 14 are bonded as materials. By contracting when the ultraviolet curable resin is cured by being irradiated with ultraviolet rays, portions other than the annular groove 32b of the flange 32a come into contact with the dielectric substrate 14 and hold the dielectric substrate 14 on the flange surface. be able to. Further, in order to prevent the resin from leaching inside the cylindrical holder 32 before the ultraviolet curable resin is cured, an O-ring and a high surface tension are formed at the boundary portion of the inner peripheral surface of the flange 32a of the cylindrical holder 32. A watertight protective member 33 (FIG. 8) such as a material may be provided. Thus, since the cylindrical holder 32 and the dielectric substrate 14 are bonded to each other in the circumferential direction by the annular groove 32b, the dielectric substrate 14 can be securely fixed in the two axial directions in the plane. Instead of the annular groove 32b, a plurality of radial grooves 32c formed at equal intervals in the circumferential direction as shown in FIG. 9 may be used. Further, instead of filling the grooves 32b and 32c with the ultraviolet curable resin, the flange surface can be solder-welded to the dielectric substrate 14. The flange 32a does not need to be fixed to the dielectric substrate 14 over the entire circumference, and a part of the flange 32a may protrude from the dielectric substrate 14 as shown in FIG. 7B. .

  As shown in FIG. 10, the light emitting element 12 is welded to the cylindrical holder 32 by laser welding or the like at equal intervals in the circumferential direction (usually three points at intervals of 120 degrees), and the front surface 14 a and the back surface 14 b of the dielectric substrate 14. Light is emitted toward the starting end of the input waveguide portion 20a along a direction perpendicular to the input waveguide portion 20a. The light emitting element 12 can be either a CAN type or a chip type. However, by using the CAN type as shown in the illustrated example, the light emitting element itself can be hermetic. An airtight structure is not required.

  A condenser lens 34 is provided between the light emitting element 12 and the start end of the input waveguide portion 20a. The light from the light emitting element 12 can be coupled to the optical waveguide 20 with high efficiency by the condenser lens 34. The condenser lens 34 may be attached to the inner peripheral surface of the cylindrical holder 32 separately from the light emitting element 12, but may be integrated with the CAN type light emitting element 12, or the rear surface 14 b of the dielectric substrate 14. It may be integrally fixed to.

  A slight adjustable clearance is provided between the inner peripheral surface of the cylindrical holder 32 and the outer peripheral surface of the light emitting element 12 before the two are fixed. When the light-emitting element 12 is fixed to the cylindrical holder 32, the area of the image formed by the condenser lens 34 on the light-emitting surface of the light-emitting element 12 is small (10 μm or less), so that it is surely moved to the start end of the input waveguide portion 20a. Consideration for propagating light is necessary. When the light is incident from the end face of the dielectric substrate 14 as in the conventional configuration, there is a problem in that it is difficult to adjust whether the light is coupled to the optical waveguide by visual means. In the present embodiment, since the light emitting element 12 is disposed on the back surface side of the dielectric substrate 14, the light from the light emitting element 12 can be visually confirmed from the front surface side of the dielectric substrate 14, and adjustment is easy. There is a feature that can be made.

  In order to further facilitate the adjustment work, a mark 14m is formed on the surface of the dielectric substrate 14 as shown in FIG. The mark 14m can be formed at the same time in the substrate manufacturing process, and may be patterned with Cr or the like. The position of the mark 14m is determined in the vicinity of the mirror 26 by a predetermined distance and in a predetermined direction.

  In the adjustment operation, the position of the light spot where the light from the light emitting element 12 hits the dielectric substrate 14 is imaged by a CCD camera installed above the surface of the dielectric substrate 14, and the light emitting element in the cylindrical holder 32 is captured. 12 position is adjusted. Since the light spot that hits the mirror 26 cannot be imaged from the surface side, first, the position in the plane parallel to the surface 14a of the light emitting element 12 and / or the parallel plane so that the light spot coincides with the mark 14m. The vertical position of the light emitting element 12 is roughly adjusted so that the inclination of the light emitting element 12 with respect to is adjusted and the focus is set at the mark 14m. Then, as shown in FIG. 12, when the light spot coincides with the mark 14m and is in focus, the position of the light emitting element 12 is moved from the mark 14m in a predetermined direction by a predetermined distance. Adjust so that it is in position. Then, in the positioned state, the light emitting element 12 is fixed to the cylindrical holder 32 by the laser welding.

  The position of the mark 14m can be an arbitrary position in the vicinity of the mirror 26, but may be provided so as to cross the optical waveguide 20 as shown in FIG. As a result, the light spot is moved along the mark 14m to the optical waveguide 20 and then moved by a predetermined distance in the direction along the optical waveguide 20, thereby adjusting the light spot to be at the position of the mirror 26. be able to.

  Returning to FIG. 4, a highly rigid metal cylindrical holder 38 that holds the light receiving element 16 and supports the dielectric substrate 14 is attached to the vertical hole 30 b of the attachment plate 30. A flange 38 a is formed at the upper end of the cylindrical holder 38, and the flange 38 a supports the back surface 14 b of the dielectric substrate 14. However, the flange 38a of the cylindrical holder 38 is only in contact with the back surface 14b and is not fixed to the back surface 14b. As a result, the dielectric substrate 14 is restrained only by the cylindrical holder 32 at one end thereof, and the generation of stress on the dielectric substrate 14 due to temperature change, vibration or the like is prevented. However, a thin elastic sheet or coating 39 may be interposed between the flange 38a and the back surface 14b.

  The light receiving element 16 is welded to the cylindrical holder 38 at equal intervals in the circumferential direction by laser welding or the like (usually three points at intervals of 120 degrees), and reflects off the mirror 28 from the end of the output waveguide portion 20d to be a dielectric. The light propagated along the direction orthogonal to the front surface 14a and the back surface 14b of the substrate 14 is received. A condensing lens 40 is provided between the end of the output waveguide portion 20 d and the light receiving element 16. Like the light emitting element 12, the light receiving element 16 can be either a CAN type or a chip type. However, by using the CAN type as shown in this example, the light emitting element itself can be hermetically sealed. Therefore, a separate airtight structure is not required.

  The condenser lens 40 may be attached to the inner peripheral surface of the cylindrical holder 38 separately from the light receiving element 16, or may be integrated with the CAN type light receiving element 16. The light from the optical waveguide 20 can be coupled to the light receiving element 16 with high efficiency by the condenser lens 40.

  Since the light-receiving surface of the light-receiving element 16 is larger than the light-emitting surface of the light-emitting element 12 (100 μm or more), the light-receiving element 16 can be attached to the cylindrical holder 38 without requiring the precision of adjustment of the light-emitting element 12.

  Instead of directly or indirectly contacting the cylindrical holder 38 with the dielectric substrate 14, as shown in FIG. 14, the cylindrical holder 38 is separated and the elastic member 41 is placed between the mounting plate 30 and the dielectric substrate 14. It may be inserted. The elastic member can be composed of RTV rubber, Teflon (registered trademark), or the like.

  The dielectric substrate 14 is provided with stray light preventing cuts 14g and 14h having V-shaped cross sections parallel to the cuts 14c and 14d on the outer side of the cuts 14c and 14d on the front surface 14a. As shown in FIG. 15, stray light preventing cuts 14i and 14j having a V-shaped or U-shaped cross section extending in a direction orthogonal to the cuts 14c and 14d are formed.

  In the optical functional element 10 configured as described above, the light emitted from the light emitting element 12 in the direction orthogonal to the front surface 14a and the back surface 14b of the dielectric substrate 14 is condensed on the mirror 26 by the condenser lens 34. After being turned 90 degrees by the mirror 26 and propagating through the input waveguide portion 20a of the optical waveguide 20, it is branched into branching waveguide portions 20b and 20c.

  When an external electric signal is input to the electrodes 22 and 24, push-pull phase modulation opposite to each other is performed on the light propagating through the branched waveguide portions 20b and 20c due to a change in refractive index due to the electro-optic effect. The modulated light is combined and output to the output waveguide portion 20d. A signal corresponding to the modulation signal is output by the multiplexing.

  The light propagating through the output waveguide portion 20d is redirected by the mirror 28 in a direction orthogonal to the dielectric substrate 14, collected by the condenser lens 40, received by the light receiving element 16, and converted into an electrical signal. The

The optical functional element 10 according to the above embodiment has the following effects.
The light emitted from the light emitting element 12 is turned 90 degrees and propagates through the optical waveguide 20, and the light that has passed through the modulation portion of the optical waveguide 20 is turned 90 degrees and received by the light receiving element 16. Since the direction and the light receiving direction differ by 180 degrees, stray light can be prevented as much as possible.
By preventing light diffusion by the condensing lenses 34 and 40, stray light can be further prevented, and the coupling efficiency between the light emitting element and the optical waveguide and between the optical waveguide and the light emitting element can be increased.
The stray light preventing cuts 14g and 14h formed on the front surface 14a of the dielectric substrate 14 and the stray light preventing cuts 14i and 14j (FIG. 15) formed on the back surface 14b can further prevent stray light more reliably. . The stray light preventing cut 14g changes the light propagating parallel to the surface 14a by reflecting on the slope opposite to the side where the mirror 26 is located in the cut 14c so as not to return to the light emitting element 12 again. To do. Similarly, the stray light prevention cut 14h reflects light propagating parallel to the surface 14a by reflecting on the back surface 14b of the dielectric substrate 14 and reflecting on the slope 14d opposite to the mirror 28 in the cut 14d. The direction is changed so as not to go to the light receiving element 16.
The stray light preventing cuts 14i and 14j are configured to change the stray light in the dielectric substrate 14 so as not to be emitted to the outside, thereby preventing reflection or the like on the side surface of the dielectric substrate 14.

In this embodiment, since the position adjustment between the light emitting element 12 and the dielectric substrate 14 can be visually monitored from the surface side, the adjustment operation can be performed automatically at high speed and easily as necessary. It can be performed. Adjustment can be performed more easily by using the mark 14m that matches the light spot of the light emitting element 12. As described above, instead of adjusting the position of the light emitting element 12, the position of the dielectric substrate 14 may be adjusted.
In addition, in this embodiment, by using a CAN type as the light emitting element 12 and the light receiving element 16, the element can be airtight.
In this embodiment, since light is incident from the back surface of the dielectric substrate 14 and light does not need to be incident from the end surface of the dielectric substrate 14, a rough surface is obtained by cutting out the wafer by dicing. It is not necessary to polish the end face of the dielectric substrate 14.

  Next, FIG. 16 is a diagram illustrating a second embodiment of the present invention. In this example, the light receiving element 16 is arranged on the surface 14 a side of the dielectric substrate 14, and the light receiving element 16 is fixed to the surface 14 a side of the dielectric substrate 14 by solder bumps 42. According to this configuration, a bare chip type light receiving element 16 can be used. A cut 14d 'is formed in the surface 14a of the dielectric substrate 14. The cut 14d' has one surface orthogonal to the surface 14a and the other surface having an angle of 45 degrees with respect to the surface 14a. It has become. A reflecting film is preferably attached to the inclined surface having an inclination angle of 45 degrees to form the mirror 28 constituting the second turning means.

  Alternatively, as shown in FIG. 17, instead of forming the notch 14d ′, the end surface of the dielectric substrate 14 may be inclined at an angle of 45 degrees, and further, an inclined surface serving as a terminal end of the output waveguide portion 20d. A reflective film to be the mirror 28 may be attached to the substrate.

  Also in this example, the same operation and effect as the first embodiment can be obtained. In this case, a bare chip type can also be suitably used as the light receiving element 16, and the vertical hole 30b and the cylindrical holder 38 can be omitted. Since the light receiving surface of the light receiving element 16 is larger than the light emitting surface of the light emitting element 12 and adjustment is not difficult, the adjustment in this example can be easily performed.

  FIG. 18 is a diagram illustrating a third embodiment of the present invention. In this example, the light emitting element 12 and the light receiving element 16 are arranged on the surface 14 a side of the dielectric substrate 14, and the light emitting element 12 and the light receiving element 16 are fixed to the front side of the dielectric substrate 14 by solder bumps 42. According to this configuration, a bare chip type can be used as the light receiving elements 12 and 16.

  A cut 14c ′ is formed in the surface 14a of the dielectric substrate 14, and the cut 14c ′ has one surface orthogonal to the surface 14a and the other surface having an angle of 45 degrees with respect to the surface 14a. It has become. A reflecting film is preferably attached to the inclined surface having an inclination angle of 45 degrees to form the mirror 26 constituting the turning means. Further, a cut 14d 'is formed, and the cut 14d' has one surface orthogonal to the surface 14a and the other surface having an angle of 45 degrees with respect to the surface 14a. A reflecting film is preferably attached to the inclined surface having an inclination angle of 45 degrees to form the mirror 28 constituting the second turning means.

  In the case of this example, since the light emitting element 12 and the light receiving element 16 and the optical waveguide 20 are in close contact with each other, the lenses 34 and 40 can be omitted.

  Alternatively, as shown in FIG. 19, the light emitting elements 12 and 16 can be attached to the dielectric substrate 14 via the attachment parts 50 and 50.

  Also in this example, the same effect as the first embodiment can be obtained. In this example, the light emitting element 12 cannot be adjusted by capturing the light spot from the surface 14a side, but the light emitting element 12 and the light receiving element 16 are chip type, so that the attachment is easy, and the light emitting element 12 and the light receiving element This can be easily performed by bonding the element 16 to the surface 14 a side of the dielectric substrate 14. Furthermore, since the light emitting element 12 and the light receiving element 16 can be combined with the dielectric substrate 14 to be a flat substrate as a whole, handling is facilitated.

FIG. 20 is a perspective view showing a fourth embodiment of the present invention.
The dielectric substrate 14 has a thermoelectromotive force acting in the z-axis direction (pyroelectric effect). Therefore, in order to avoid this, it is necessary to short-circuit both side surfaces of the dielectric substrate 14. As a countermeasure for this, as shown in FIG. 20, metal patterns (for example, gold patterns) 14n and 14n are further formed on both sides of the optical waveguide 20 on the surface 14a of the dielectric substrate 14, and these metal patterns 14n and 14n are optically transmitted. It is good to connect with the thin pattern which is a conductive member which does not affect the waveguide 20, or to connect with a wire. Furthermore, as shown in FIG. 21, a conductive paint 14o may be applied to both sides of the dielectric substrate 14 so as to be in contact with the metal pattern 14n. Accordingly, even when the dielectric substrate 14 is supported in a cantilever manner as shown in FIG. 4 or FIG. 14, it is possible to short-circuit both side surfaces of the dielectric substrate 14.

1 is an overall perspective view of an optical functional element of the present invention. FIG. 2 is a cutaway perspective view of FIG. 1. FIG. 2 is a plan view of FIG. 1 (the vertical / horizontal scale ratio is changed from that of FIG. 1 for the sake of explanation). It is a longitudinal cross-sectional view of FIG. (A) is an enlarged perspective view near the start end of the input waveguide portion or near the end of the output waveguide portion, and (b) is an enlarged cross-sectional view of the start end of the input waveguide portion. It is an expanded sectional view showing other examples near the starting end of an input waveguide portion. It is a top view which shows the relationship between a cylindrical holder and a dielectric substrate (it shows with a virtual line). It is a fragmentary sectional view which shows the adhering state of a cylindrical holder and a dielectric substrate. It is a fragmentary perspective view showing the other example of a cylindrical holder. It is a bottom view which shows the adhering state of a light emitting element and a cylindrical holder. It is an explanatory perspective view showing adjustment of a light emitting element. It is an enlarged plan view of a mark and a light spot. It is an enlarged plan view showing the relationship between another mark, an optical waveguide, and a light spot. It is a longitudinal cross-sectional view showing a modification. It is a perspective view of the back surface side of a dielectric substrate. It is a longitudinal section showing a 2nd embodiment of the present invention. It is a longitudinal cross-sectional view showing the modification of 2nd Embodiment of this invention. It is a longitudinal section showing a 3rd embodiment of the present invention. It is a longitudinal cross-sectional view showing the modification of 3rd Embodiment of this invention. It is a perspective view of the dielectric substrate showing 4th Embodiment of this invention. It is a perspective view of the dielectric substrate showing 4th Embodiment of this invention. It is a top view showing the conventional optical functional element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical functional element 12 Light emitting element 14 Dielectric board | substrate 14a Front surface 14b Back surface 14n Metal pattern (electroconductive pattern)
14o conductive paint (conductive material)
16 Light receiving element 20 Optical waveguide 20a Input waveguide portion 20b Branching waveguide portion (modulation portion)
20c Branching waveguide part (modulation part)
20d Output waveguide portion 26 Mirror (first turning means)
28 Mirror (second turning means)

Claims (9)

A light-emitting element as a light source; a dielectric substrate on which an optical waveguide is formed; and a light-receiving element that converts light into electricity. The light from the light-emitting element is modulated by an external electric signal and modulated. In an optical functional element that outputs light as an electrical signal by the light receiving element,
The optical waveguide includes an input waveguide portion formed on a plane parallel to the plate surface of the dielectric substrate, a modulation portion connected to the input waveguide portion and modulated by the external electric signal, and the modulation It consists of an output waveguide part connected to the part,
The light emitting element emits light toward a start end of the input waveguide portion along a direction orthogonal to the plane.
An optical functional element characterized in that a turning means for directing light from a direction orthogonal to the plane toward the input waveguide portion is provided at the starting end of the input waveguide portion. The terminal of the output waveguide portion is provided with second turning means for directing light propagating through the output waveguide portion in a direction perpendicular to the plane,
2. The optical functional element according to claim 1, wherein the light receiving element receives light that is changed in direction by a second changing means and propagates in a direction orthogonal to the plane.   The optical functional element according to claim 1, wherein the plane is a surface of the dielectric substrate, and the light emitting element is disposed on a back surface side of the dielectric substrate.   4. The optical functional element according to claim 3, wherein the light receiving element is disposed on a back side of the dielectric substrate.   4. The optical functional element according to claim 3, wherein the light receiving element is disposed on a surface side of the dielectric substrate.   3. The optical functional element according to claim 1, wherein the plane is a surface of the dielectric substrate, and the light emitting element and the light receiving element are disposed on a surface side of the dielectric substrate.   In the vicinity of the starting end of the input waveguide portion of the dielectric substrate, the distance and direction from the starting end of the input waveguide portion are known, and a marker is formed for matching the light spot from the light emitting element during adjustment. The optical functional element according to claim 1, wherein the optical functional element is an optical functional element.   8. The conductive pattern according to claim 1, wherein conductive patterns are formed on both sides of the optical waveguide on the plane, and the conductive patterns are connected to each other by a conductive member. Optical functional element.   9. The optical functional element according to claim 8, wherein a conductive material that is electrically connected to the conductive pattern is applied to a side surface of the dielectric substrate.

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