Optical waveguide element and optical axis adjustment method

Abstract

The optical waveguide element of the present disclosure is provided with: a waveguide (2) that propagates light; a cladding layer (3) that is composed of an upper cladding layer (3b) and a lower cladding layer (3a), a lower surface of the upper cladding layer (3b) is in contact with one face of the waveguide (2) and a rough surface (5) is formed on an upper surface that is exposed to the outside, an upper surface of the lower cladding layer (3a) is in contact with the other face of the waveguide (2) and a reflection surface (4) is formed on a lower surface; an incident end surface (7) that is provided at one end of the waveguide (2) and the cladding layer (3); and an emission end surface (8) that is provided at the other end of the waveguide (2) and the cladding layer (3), so that most of the components of the light propagating in the cladding layer (3) become scattered light (18) and do not emit from the emission end surface 8, the output of the emission light (15) is received by a power meter (40), and thus the output of the components of the incident light (10) that are coupled to the waveguide (2) can be measured.

Description

Technical Field

[0001] This disclosure relates to optical waveguide elements and optical axis adjustment methods. Background Technology

[0002] One method for guiding light from the outside into optical waveguide elements used in optical fiber communication is to achieve optical coupling via a lens. In this method, the incident light beam diameter is minimized by adjusting the focal point to the incident end face of the waveguide element, and the angle of the incident light is adjusted so that the optical axis after incident becomes parallel to the waveguide. However, since the focal point of the incident light cannot be directly observed, a power meter or similar device is needed to receive the light emitted from the exit end face of the waveguide, and while measuring the output of the emitted light, either or both of the lens and the light source are positioned optimally.

[0003] Even when the incident light is not coupled with the waveguide light but is incident on the inside of the optical waveguide element from the cladding, the incident light is totally reflected at the boundary between the cladding and the outer periphery because the outer periphery of the cladding is covered by air or bonding material. Therefore, even light propagating inside the cladding will be output from the cladding's output end face, which is the same as the waveguide's output end face.

[0004] On the other hand, when the beam diameter is minimized and the focal point is adjusted to the incident end face of the waveguide so that the optical axis angle of the incident light is aligned with the propagation axis of the waveguide, the incident light propagates inside the waveguide and exits from the exit end face. Even the light exiting from the exit end face of the cladding mentioned above propagates with almost the same output as the light exiting from the exit end face of the waveguide. Therefore, even if the output of the light emitted from the exit end face is measured with a power meter and the output is increased by adjusting the position of the lens and the light source, the incident light may not be optically coupled to the optical waveguide. Therefore, in the above-described optical axis adjustment method, it is difficult to achieve high-efficiency optical coupling of the incident light to the waveguide.

[0005] To address the problems of the aforementioned optical axis adjustment methods, for example, according to the optical waveguide element and optical axis adjustment method disclosed in Patent Document 1, the optical waveguide element includes a waveguide, a planar waveguide arranged relative to the waveguide in the X-axis direction, and a series of tiny concave pits inside the planar waveguide that change the optical path along the Y-axis direction. A camera positioned above the concave pits observes the reflected light from the concave pits, and a lens is adjusted in the Y-axis direction to increase the light intensity, thereby coupling the incident light to the planar waveguide. Next, the reflected light from the concave pits is adjusted in the X-axis and Z-axis directions to bring it closer to the waveguide, ultimately adjusting until the light observed by the camera disappears, thus achieving optical coupling of the incident light to the waveguide.

[0006] In addition, the waveguide-type optical device operation characteristic evaluation method described in Patent Document 2, in the waveguide-type optical device, as a means of changing the optical path above the waveguide, uses a thin layer of a phosphor or scatterer with a higher refractive index than the waveguide to be disposed on the upper surface of the waveguide.

[0007] In the optical axis adjustment method of the optical component described in Patent Document 3, as a way to monitor the light from the waveguide emission end face and adjust the optical axis, the following method is disclosed: on the XY plane perpendicular to the optical axis, the optical axis is slightly moved from a reference position to a position of 2 points or more in the X-axis direction and the Y-axis direction, respectively, and the optical coupling intensity is measured at a position of 5 points or more. Based on the measurement data, the peak positions of the light intensity in the X-axis direction and the Y-axis direction are determined, thereby adjusting the optical axis to that position.

[0008] Patent Document 1: Japanese Patent Application Publication No. 2011-059539

[0009] Patent Document 2: Japanese Patent Application Publication No. 05-248991

[0010] Patent Document 3: Japanese Patent Application Publication No. 06-281850

[0011] However, in the optical waveguide element and optical axis adjustment method disclosed in Patent Document 1, for example, if the optical coupling degree of the incident light to the waveguide becomes higher than a certain level, the reflected light observed by the camera disappears. Therefore, there are problems such as difficulty in obtaining the optical coupling of the incident light to the waveguide with the maximum efficiency.

[0012] Light traveling from a material with a low refractive index to a material with a high refractive index does not undergo total internal reflection but propagates entirely within the material with the high refractive index. In the waveguide-type optical device disclosed in Patent Document 2, because a thin layer including a phosphor or scatterer with a refractive index higher than the waveguide is configured, even when light can be incident on the waveguide, some light is lost due to propagation within the thin layer including the phosphor or scatterer with a high refractive index. Therefore, there is a problem of low waveguide propagation efficiency.

[0013] Furthermore, in the optical axis adjustment method of the optical component disclosed in Patent Document 3, it is difficult to efficiently adjust the optical axis incident on the waveguide because it is impossible to separate the light incident from the incident end face onto the waveguide and the light incident onto the cladding. Summary of the Invention

[0014] This disclosure is made to eliminate the aforementioned problems, and its purpose is to provide an optical waveguide element, a light guide plate, and an optical axis adjustment method that enables incident light to be optically coupled to the waveguide with high efficiency and ease in a method of optical coupling via a lens as a way of introducing light from the outside into an optical waveguide element.

[0015] The optical waveguide element disclosed in this application is characterized in that it comprises: a waveguide for propagating light; a cladding layer consisting of an upper cladding layer whose lower surface is connected to one side of the waveguide and a lower cladding layer whose upper surface is connected to the other side of the waveguide; two side surfaces disposed on both sides of the upper and lower cladding layers; an incident end face disposed at one end of the waveguide and the cladding layer; and an exit end face disposed at the other end of the waveguide and the cladding layer. Either the upper surface of the forming plane of the upper cladding layer or the lower surface of the forming plane of the lower cladding layer is inclined relative to the waveguide, while the other is parallel to the waveguide. The thickness of the cladding layer in the vertical direction of the waveguide is thinner on the exit end face side than on the incident end face side. The distance between the upper surface of the forming plane of the upper cladding layer and the lower surface of the forming plane of the lower cladding layer gradually decreases from the incident end face to the exit end face.

[0016] The optical axis adjustment method disclosed in this application is characterized by comprising: a step of focusing light from a light source onto the incident end face of the optical waveguide element using a lens; a step of measuring the output emitted from the exit end face of the optical waveguide element using a power meter; and a step of adjusting the focal position and incident beam angle of the focused incident light by adjusting the position and angle of any one or both of the light source and the lens, so as to increase the output.

[0017] The optical waveguide element disclosed in this application achieves the effect of enabling incident light to be optically coupled to the waveguide with high efficiency and ease.

[0018] The light guide plate disclosed in this application serves the purpose of being installed on an optical waveguide element to enable incident light to be optically coupled to the waveguide of the optical waveguide element with high efficiency and ease.

[0019] According to the optical axis adjustment method disclosed in this application, since the component of incident light that is not optically coupled to the waveguide can be scattered from the rough surface of the upper cladding to the outside of the optical waveguide element, the intensity and position of the scattered light can be observed with an imaging element, and the position of either or both of the light source and the lens can be adjusted based on the intensity of the scattered light measured by the imaging element, the scattered light area, and the output measured by the power meter, thus achieving the effect of optical axis adjustment that enables the incident light to be optically coupled to the waveguide with high efficiency and ease. Attached Figure Description

[0020] Figure 1A This is a cross-sectional view showing the state of the optical waveguide element and optical axis adjustment method according to Embodiment 1 before optical axis adjustment. Figure 1B It means in Figure 1A It also includes a cross-sectional view of the light source and lens before the optical axis is adjusted. Figure 1C It is a graph illustrating coordinates.

[0021] Figure 2 This indicates that the optical waveguide element involved in Embodiment 1 is along... Figure 1A The diagram shows the intensity distribution of incident light across a cross-section cut by line AA.

[0022] Figure 3 This is a cross-sectional view showing the state in which the optical axis of the incident light is being adjusted in the optical waveguide element of Embodiment 1.

[0023] Figure 4 This is a cross-sectional view showing the state when the optical axis of the incident light in the optical waveguide element according to Embodiment 1 is adjusted.

[0024] Figure 5 This is a cross-sectional view showing the state in which the optical axis of the incident light is being adjusted in the optical waveguide element according to Embodiment 1.

[0025] Figure 6 This is a cross-sectional view showing the shape of the optical waveguide element in the optical waveguide element according to Embodiment 1.

[0026] Figure 7 This is a cross-sectional view showing the state in which the optical axis of the incident light is being adjusted in the optical waveguide element according to Embodiment 2.

[0027] Figure 8 This is a cross-sectional view showing the state in which the optical axis of the incident light is being adjusted in the optical waveguide element according to Embodiment 3.

[0028] Figure 9 This is a schematic diagram of the optical waveguide element involved in Embodiment 4.

[0029] Figure 10 This is a cross-sectional view showing the state in which the optical axis of the incident light is being adjusted in the optical waveguide element according to Embodiment 5.

[0030] Figure 11 This is a cross-sectional view showing the state in which the optical axis of the incident light is being adjusted in the optical waveguide element according to Embodiment 6.

[0031] Figure 12 This is a cross-sectional view showing the optical waveguide element and light guide plate involved in Embodiment 7.

[0032] Figure 13 This is a cross-sectional view showing the optical waveguide element and light guide plate involved in Embodiment 8.

[0033] Figure 14 This is a cross-sectional view showing the optical waveguide element and light guide plate involved in Embodiment 9.

[0034] Figure 15 This is a cross-sectional view showing the state in which the optical axis of the incident light is being adjusted in the optical waveguide element involved in the comparative example.

[0035] Figure 16 This is a cross-sectional view showing the state when the optical axis of the incident light in the optical waveguide element involved in the comparative example has been adjusted. Detailed Implementation

[0036] Implementation Method 1

[0037] Figure 1A This is a cross-sectional view showing the state of the optical waveguide element 100 and the optical axis adjustment method according to Embodiment 1 before the optical axis is adjusted. Figure 1B It means in Figure 1A It also includes a cross-sectional view of the light source and lens before the optical axis is adjusted.

[0038] like Figure 1A As shown, the optical waveguide element 100 according to Embodiment 1 is composed of a laminate, which consists of a waveguide 2, a lower cladding layer 3a disposed in contact with one side of the waveguide 2, and an upper cladding layer 3b disposed in contact with the other side of the waveguide 2. The lower cladding layer 3a and the upper cladding layer 3b are collectively referred to as cladding layer 3.

[0039] like Figure 1A As shown, the direction along waveguide 2 is defined as the Z direction. In the plane perpendicular to the Z direction, the direction parallel to waveguide 2 is defined as the X direction, and the direction perpendicular to the X direction, i.e., the stacking direction, is defined as the Y direction. Furthermore, for the Y direction, the upper cladding 3b side is defined as the upper cladding 3, and the lower cladding 3a side is defined as the lower cladding 3, thus defining the vertical direction.

[0040] Furthermore, in the following explanation, "parallel" includes not only cases of complete parallelism but also cases of substantial parallelism; similarly, "identical" includes not only cases of complete sameness but also cases of substantial sameness.

[0041] The optical waveguide element 100 has: an incident end face 7, disposed at one end of the optical waveguide element 100 and parallel to the XY plane; and an exit end face 8, disposed at the other end of the optical waveguide element 100 and parallel to the XY plane. That is, the incident end face 7 and the exit end face 8 are in a positional relationship opposite each other. In addition, the incident end face 7 is formed by the surface of one end of the waveguide 2 and the cladding 3, and the exit end face 8 is formed by the surface of the other end of the waveguide 2 and the cladding 3.

[0042] The lower cladding 3a has a reflecting surface 4 parallel to the XZ plane, and the upper cladding 3b has a rough surface 5. The reflecting surface 4 and the rough surface 5 are opposite each other via the waveguide 2. That is, the lower surface of the upper cladding 3b is in contact with one side of the waveguide 2 and the rough surface 5 is formed on its upper surface, while the upper surface of the lower cladding 3a is in contact with the other side of the waveguide 2 and the reflecting surface 4 is formed on its lower surface.

[0043] like Figure 1B As shown, the incident light 10 is light generated from the light source 1a and transmitted through the lens 1b. It propagates while decreasing in diameter in a direction parallel to the Z-axis, and has a focal point 14 where the beam diameter is minimized. The incident light 10, passing through the focal point 14, increases in beam diameter as it propagates. By adjusting the focal point 14 to align with the incident end face 7 on the waveguide 2 side, high optical coupling to the waveguide 2 can be achieved.

[0044] Figure 2 schematic representation Figure 1A The light intensity distribution of incident light 10 at section AA. The light intensity is maximum at the center of the beam. Here, normalizing the maximum light intensity to 1, it will become 1 / e of the maximum light intensity. 2 When the positions of light intensity are set as w and -w, the diameter 2w of the circle represented by w and -w is called the beam diameter. Figure 1A The optical axis 12 of the incident light beam diameter and the optical axis 17 of the outgoing light beam diameter are shown respectively.

[0045] Although most of the incident light 10 reaching the incident end face 7 is incident into the interior of the optical waveguide element 100, a portion of the incident light 10 is reflected by the incident end face 7 and becomes return light due to the refractive index difference between the air layer before incident and the optical waveguide element 100. In addition, even when a non-reflective film is applied to the incident end face 7 to suppress the reflection of the incident light 10, it is not possible to make the reflected light completely zero.

[0046] In cases where the reflected light, i.e., the returned light, negatively affects the characteristics of the optical waveguide element 100, in order to ensure that the returned light is not parallel to the principal axis 11 of the incident light but has a certain angle, the incident end face 7 of the optical waveguide element 100 can be adjusted as follows: Figure 1A The structure can be configured to tilt in the θX direction, or it can also tilt in the θY direction. Among these, in... Figure 1C The relationship between the X, Y, Z directions and the θX, θY, θZ directions is shown.

[0047] Similarly, light propagating inside waveguide 2 is output as outgoing light 15 from exiting end face 8, but a portion of outgoing light 15 is reflected at exiting end face 8 to become returning light. Therefore, similar to incident end face 7, exiting end face 8 can also be configured to be inclined in the θX or θY direction.

[0048] Light incident from the incident end face 7 into the interior of the optical waveguide element 100 propagates within the optical waveguide element 100 and is output from the exit end face 8. The output, i.e., the light intensity, of the output light 15 is measured using a power meter 40. The power meter 40 is configured such that its light-receiving surface is perpendicular to the principal axis 16 of the output light.

[0049] The incident light 10 transmitted through lens 1b propagates while decreasing in beam diameter in a direction parallel to the Z-axis, and has a focal point 14 where the beam diameter is minimized. The incident light 10 passing through focal point 14 increases in beam diameter as it propagates. Although high optical coupling with waveguide 2 can be achieved by adjusting focal point 14 to align with the incident end face 7 on the waveguide 2 side, generally, before the optical axis is adjusted, focal point 14 and incident end face 7 are not aligned; therefore, only a portion 13 of the incident light is optically coupled to waveguide 2. Of the uncoupled component of the incident light 10, a portion enters the interior of the optical waveguide element 100 from the incident end face 7 on the cladding 3 side, while the remaining portion propagates to the exterior of the optical waveguide element 100.

[0050] That is, although by adjusting the X-axis, Y-axis, Z-axis, θX-axis, and θY-axis of any one or both of the light source 1a and lens 1b, the output of the emitted light 15 measured by the power meter 40 is made as large as possible, thereby achieving high-efficiency optical coupling relative to the waveguide 2, it cannot be said that the optical coupling is high enough under this condition.

[0051] In the optical waveguide element 100 according to Embodiment 1, a rough surface 5 is formed on the upper surface of the upper cladding 3b. When light propagating in the cladding 3 is incident on the rough surface 5 of the upper cladding 3b, a portion of the light is scattered as scattered light 18 to the outside of the optical waveguide element 100. This scattered light 18 is observed by an imaging element 41 provided in the upper part of the optical waveguide element 100 in the Y direction. In order to minimize the light intensity of the observed scattered light 18 and the area emitting the scattered light, i.e., the scattered light area, the X-axis, Y-axis, Z-axis, θX-axis, and θY-axis of any one or both of the light source 1a and the lens 1b are adjusted, thereby achieving optical coupling with higher efficiency relative to the waveguide 2.

[0052] The operation of the optical waveguide element 100 according to Embodiment 1 will be described in more detail below.

[0053] Light incident from the incident end face 7 on the cladding 3 side into the interior of the optical waveguide element 100 propagates within the cladding 3 between the reflecting surface 4 of the lower cladding 3a and the rough surface 5 of the upper cladding 3b, undergoing serrated reflection. Due to the roughness of the surface 5, not all light is totally reflected between the upper cladding 3b and the external air layer; instead, a portion becomes scattered light 18, leaking out from the upper cladding 3b to the outside of the optical waveguide element 100. For light propagating within the cladding 3 of the optical waveguide element 100 through serrated reflection between the reflecting surface 4 of the lower cladding 3a and the rough surface 5 of the upper cladding 3b, and subsequent multiple scattering on the rough surface 5, most of the component becomes scattered light 18 and does not exit from the exit end face 8.

[0054] On the other hand, light incident from the incident end face 7 on the waveguide 2 side into the interior of the optical waveguide element 100 propagates inside the waveguide 2 due to the refractive index difference between the waveguide 2 and the cladding 3, thus not producing scattering caused by the rough surface 5, and is output as the outgoing light 15 from the outgoing end face 8 on the waveguide 2 side. The output of the outgoing light 15 is received by the power meter 40, thereby enabling the measurement of the component of the incident light 10 that is coupled to the waveguide 2.

[0055] Alternatively, the imaging element 41 can be positioned at the upper part of the optical waveguide element 100 in the Y direction. By imaging the rough surface 5 with the imaging element 41, the location where the scattered light 18 is generated can be determined.

[0056] The method for adjusting the optical coupling between the power meter 40 and the waveguide 2 is explained.

[0057] When the incident light 10 is deflected too much and the light does not enter the optical waveguide element 100 from the incident end face 7, the scattered light 18 cannot be observed in the imaging element 41. In addition, the output of the outgoing light 15 cannot be measured by the power meter 40.

[0058] However, since the area of ​​the incident end face 7 obtained by adding waveguide 2 and cladding 3 is sufficiently large compared to the area of ​​the incident end face 7 on the waveguide 2 side, adjusting either or both of the light source 1a and lens 1b will... Figure 1A It is relatively easy to direct a portion of the incident light 10 into the interior of the optical waveguide element 100 from the incident end face 7. In this case, since the focal point 14 is not aligned with the incident end face 7, the beam diameter at the incident end face 7 is large, and only a portion 13 of the incident light is optically coupled to the waveguide 2. The light incident on the waveguide 2 propagates inside the waveguide 2 and, as the output light 15 from the exit end face 8, can be measured by the power meter 40.

[0059] Next, adjust either or both of the light source 1a and lens 1b in the Y direction until the emitted light 15, as measured by the power meter 40, reaches its maximum. Figure 3 This state is shown. The component of incident light 10 with the highest light intensity is optically coupled to waveguide 2, propagates inside waveguide 2, and is output as outgoing light 15 from outgoing end face 8.

[0060] Next, similarly, either or both of the light source 1a and lens 1b are moved in the X direction to adjust the output of the emitted light 15 as measured by the power meter 40 to be maximum. Furthermore, the focal point 14 is moved in the Z direction to adjust the output of the emitted light 15 from the emission end face 8 as measured by the power meter 40 to be maximum.

[0061] By repeatedly adjusting the position of the focal point 14 on the X, Y, and Z axes, the output of the emitted light 15, as measured by the power meter 40, is increased. If the adjusted output of the emitted light 15 is insufficient to represent the output of the emitted light 15 as envisioned based on the output of the incident light 10, the position of the focal point 14 on the X, Y, and Z axes is adjusted again after moving the θX and θY axes of either the light source 1a or the lens 1b, so that the output of the emitted light 15, as measured by the power meter 40, is maximized, thereby enabling the incident light 10 to be optically coupled to the waveguide 2 with high efficiency.

[0062] Figure 4 This is a cross-sectional view showing the state in which the incident light 10 is optically coupled to the waveguide 2 in the optical waveguide element 100 with high efficiency. Most of the components of the incident light 10 are optically coupled to the waveguide 2 and, after propagating inside the waveguide 2, can be output as the output light 15 from the output end face 8.

[0063] Figure 5 This is a cross-sectional view showing the state where the focal point 14 in the optical waveguide element 100 is at the same position in the Z direction as the incident end face 7, but offset in the Y direction. Since the beam diameter of the focal point 14 is almost identical to the mode field diameter of the waveguide 2, the position of the beam diameter of the focal point 14 is taken from the position of the incident light 10 with the largest optical coupling. Figure 4 The state is offset in the Y direction by about twice the thickness of waveguide 2, so that almost all the light is not coupled to waveguide 2.

[0064] On the other hand, when the focal point 14 is offset from the incident end face 7 in the Z direction, since the beam diameter at the incident end face 7 is larger than the beam diameter at the focal point 14, even if the beam is offset by about twice the thickness of the waveguide 2, a portion of the incident light 10 will still be optically coupled with the waveguide 2 and output as the outgoing light 15, which is measured by the power meter 40. Therefore, since the Z-direction offset of the focal point 14 can be determined, the position of the focal point 14 on the X, Y, and Z axes can be moved again to maximize the output of the outgoing light 15 measured by the power meter 40, thereby allowing adjustment to achieve the maximum output of the outgoing light 15. Figure 4 The state shown represents the highest efficiency optical coupling.

[0065] The following describes the adjustment method for obtaining optical coupling between the imaging element 41 and the waveguide 2.

[0066] Starting from the state where the incident light 10 is significantly deflected, adjust either or both of the light source 1a and lens 1b, such as... Figure 1A As shown, a portion of the incident light 10 is incident from the incident end face 7 into the interior of the optical waveguide element 100. At this time, since the focal point 14 is not aligned with the incident end face 7, the beam diameter at the incident end face 7 is large. Because the light is incident from the incident end face 7 on the cladding 3 side into the interior of the optical waveguide element 100, scattered light 18 is generated at the rough surface 5 of the upper cladding 3b.

[0067] Next, adjust either or both of the light source 1a and lens 1b in the Y direction to increase the intensity and area of ​​the scattered light 18 observed by the imaging element 41. Figure 3 This state is shown. Most of the light incident inside the optical waveguide element 100 is scattered to the outside of the optical waveguide element 100 as scattered light 18, thus becoming the state where the light intensity of the scattered light 18 and the scattered light region are the largest.

[0068] As the proportion of the output of the incident light 10 coupled with the waveguide 2 increases, the light intensity and the scattered light area of ​​the scattered light 18 decrease. Therefore, by adjusting either or both of the light source 1a and the lens 1b in the X direction, the light intensity and the scattered light area of ​​the scattered light 18 observed by the imaging element 41 are reduced.

[0069] Furthermore, the focus 14 is moved in the Z direction to minimize the light intensity and scattered light area of ​​the scattered light 18 observed by the imaging element 41. In this way, the position of the focus 14 on the X, Y, and Z axes is repeatedly adjusted to minimize the light intensity and scattered light area of ​​the scattered light 18 observed by the imaging element 41.

[0070] Even if the X, Y, and Z axes of either or both of the light source 1a and lens 1b are repeatedly adjusted to maximize the output of the power meter 40, there are still cases where the output measured by the power meter 40 is weaker than the incident light 10, and the scattered light 18 is observed by the imaging element 41. In such cases, the principal axis 11 of the incident light is tilted relative to the incident end face 7, and the principal axis 11 of the incident light incident into the waveguide 2 has an angle relative to the Z direction, so the light component with the larger angle leaks from the waveguide 2 into the cladding 3.

[0071] If the offset angle is in the θY direction, the light intensity of the scattered light 18 and the area of ​​the light scattering region measured by the imaging element 41 will deviate on both sides of the waveguide 2 within the XZ plane. By adjusting the angle of the principal axis 11 of the incident light in the direction of eliminating the deviation of the scattered light 18, i.e., in the θY direction, the output of the emitted light 15 will increase, while the scattered light 18 will decrease.

[0072] If the offset angle is in the θX direction, the position of the scattered light 18 in the Z direction, measured by the imaging element 41, away from or near the incident end face 7, is observed. By adjusting the angle of the principal axis 11 of the incident light in the θX direction, the output of the emitted light 15 increases, and the scattered light 18 decreases.

[0073] In this way, by observing the location of the scattered light 18, i.e. the light scattering region, through the imaging element 41, the angle of the principal axis 11 of the incident light can be adjusted, thus enabling the incident light 10 to be optically coupled to the waveguide 2 more efficiently.

[0074] In the figures illustrating the optical waveguide element 100 according to Embodiment 1, the angle of the returned light from the incident end face 7 and the exit end face 8 is tilted in the θY direction, so that they have an angle relative to the principal axis 11 of the incident light. Generally, when the refractive index of the waveguide 2 is about 1.5, by setting the tilt angle of the incident end face 7 and the exit end face 8 to about 8°, the optical coupling of the returned light relative to the incident light 10 can be suppressed to more than 30 dB.

[0075] Figure 6 This is a cross-sectional view showing the state in which light propagating inside the cladding 3 at least once irradiates the rough surface 5 to generate scattered light 18 when the focal point 14 in the optical waveguide element 100 is not optically coupled to the waveguide 2.

[0076] Let H be the height (thickness) of the optical waveguide element 100 in the Y direction, n be the refractive index of the cladding 3, and θ be the incident beam angle of the incident light 10. in In the case of the optical waveguide element 100, the length L is set in such a way as to satisfy the following formula (1).

[0077] [Formula 1]

[0078]

[0079] By setting the length L of the optical waveguide element 100 in this way, the light propagating inside the cladding 3 will illuminate the rough surface 5 at least once. Therefore, as the light coupled to the waveguide 2 increases, the output of the outgoing light 15 also increases. Thus, by adjusting the positions of the focal points 14 on the X, Y, and Z axes in a way that maximizes the output of the outgoing light 15, the optical coupling can be maximized.

[0080] Furthermore, the cladding 3 can also be configured to be bonded to a substrate (not shown). Generally, since the refractive index of the substrate is higher than that of air, the angle of total internal reflection inside the cladding 3 becomes larger relative to the normal of the reflecting surface 4. Therefore, a portion of the incident light 13 with a small angle is not totally reflected and propagates inside the substrate. In addition, when the refractive index of the substrate is higher than that of the cladding 3, the propagating light is not totally reflected between the cladding 3 and the substrate.

[0081] Even when the refractive index of the substrate is higher than that of the cladding 3, reflection occurs between the substrate and the outer layer of the substrate, resulting in the same effect as the optical waveguide element 100 shown in FIG1. ​​When there is propagation loss at the junction of the cladding 3 and the substrate, or when there is propagation loss between the substrate and the outer layer, the light incident on the incident end face 7 on the cladding 3 side is further attenuated, and therefore it is easier to separate from the outgoing light 15.

[0082] In the optical waveguide element 100 and optical axis adjustment method described in Embodiment 1, the component of the incident light 10 that is not optically coupled to the waveguide 2 is scattered from the rough surface 5 of the upper cladding 3b to the outside of the optical waveguide element 100. While observing the light intensity and position of the scattered light 18 with the imaging element 41, the position of either or both of the light source 1a and the lens 1b is adjusted to maximize the output of the outgoing light 15 that is optically coupled to the waveguide 2 and measured by the power meter 40. Thus, the effect of enabling the incident light 10 to be optically coupled to the waveguide 2 with high efficiency and ease is achieved.

[0083] Comparative example

[0084] The following is an explanation of the comparative examples.

[0085] Figure 15 This is a cross-sectional view showing the propagation state of incident light 10 in the optical waveguide element 50, which is used as a comparative example, when the incident light 10 is not optically coupled to the waveguide 2 but is incident from the cladding 3 into the interior of the optical waveguide element 50. Since the outer periphery of the cladding 3 is covered by air or bonding components, the boundary surface functions as a reflecting surface 4, so the incident light 10 is totally internally reflected at the boundary between it and the cladding 3. Therefore, even light propagating inside the cladding 3 will be output as outgoing light 15 from the outgoing end face 8 on the cladding 3 side.

[0086] On the other hand, when the beam diameter of the incident light 10 is adjusted to the incident end face 7 on the waveguide 2 side so that the angle of the principal axis 11 of the incident light is aligned with the propagation axis of the waveguide 2, such as Figure 16 The cross-sectional view shows the state when the optical axis of the incident light is adjusted. The incident light 10 propagates inside the waveguide 2 and is output from the output end face 8 on the side of the waveguide 2.

[0087] However, even Figure 15 The emitted light 15 shown is output from the emission end face 8 on the cladding 3 side, and is also in accordance with... Figure 16 The emitted light 15 from the emitting end face 8 on the waveguide 2 side exhibits almost identical output propagation. Therefore, even if the output of the emitted light 15 from the emitting end face 8 is measured using a power meter 40, and the output of the emitted light 15 is increased by adjusting the positions of the lens and the light source (neither shown), the incident light 10 may not necessarily be optically coupled to the waveguide 2. That is, in using the optical waveguide element 50 involved in the comparative example and the optical axis adjustment method of the optical waveguide element 50, it is difficult to make the incident light 10 optically coupled to the waveguide 2 with high efficiency.

[0088] Implementation Method 2

[0089] Figure 7 This is a cross-sectional view showing the state in which the incident light 10 is not optically coupled to the waveguide 2 in the optical waveguide element 110 and optical axis adjustment method according to Embodiment 2.

[0090] exist Figure 7 In the optical waveguide element 110, the waveguide 2 is composed of the following parts: a cladding 3, which is composed of a lower cladding 3a and an upper cladding 3b that are in contact with the upper and lower surfaces of the waveguide 2; an incident end face 7, which is disposed at one end of the optical waveguide element 110 and is parallel to the XY plane; an exit end face 8, which is disposed at the other end of the optical waveguide element 110 and is parallel to the XY plane; a reflecting surface 4, which is disposed at the lower cladding 3a and is parallel to the XZ plane; and an inclined surface 6, which is disposed at the upper cladding 3b and is opposite to the reflecting surface 4.

[0091] The inclined surface 6 of the upper cladding 3b is inclined at an angle θ relative to the surface parallel to the reflecting surface 4 of the lower cladding 3a. g Inclined. That is, the inclined surface 6 of the upper cladding 3b is inclined at an angle θ relative to the waveguide 2. g tilt.

[0092] Inclination angle θ g The angle is such that the area of ​​the exit end face 8 becomes smaller than the area of ​​the incident end face 7. That is, the height (thickness) H of the incident end face 7 is... in The height (thickness) H of the exit end face is greater than 8. out The relationship is such that the thickness of the cladding 3 in the vertical direction (Y direction) of waveguide 2 is thinner on the exit end face 8 side than on the incident end face 7 side. Furthermore, for the emitted light 15 and the power meter 40, since it is the same as in Embodiment 1, the thickness of the cladding 3 is thinner on the exit end face 8 side than on the incident end face 7 side. Figure 7 Omitted in .

[0093] Since the intensity of the incident light 10 is 1 / e of the maximum intensity... 2The optical axis 12 of the incident light beam diameter forms an angle with respect to the principal axis 11 of the incident light, so the light incident from the incident end face 7 on the cladding 3 side and propagating inside the optical waveguide element 110 is reflected at the reflecting surface 4 of the lower cladding 3a and the inclined surface 6 of the upper cladding 3b.

[0094] Here, because the inclined surface 6 of the upper cladding 3b is inclined at an angle θ relative to the XZ surface in the θY direction. g Because the surface is tilted, the angle of the light incident on the tilted surface 6 relative to the normal of the tilted surface 6 is smaller than the tilt angle θ. g The corresponding angle. Therefore, the light incident on inclined plane 6 does not satisfy the condition for total internal reflection, but rather... Figure 7 The optical axis 17 of the emitted light beam diameter is shown, and it is output from the inclined surface 6 to the outside of the optical waveguide element 110.

[0095] at the tilt angle θ g In the case of a small reflection, the light propagating inside the optical waveguide element 110 initially satisfies the condition for total internal reflection, thus undergoing total internal reflection and propagating in a sawtooth pattern between the inclined surface 6 and the reflecting surface 4. However, each time the light is reflected at the inclined surface 6, the angle relative to the normal of the inclined surface 6 becomes shallower, i.e., smaller. When the light propagating inside the optical waveguide element 110 is reflected N times at the inclined surface 6, the principal axis of the propagating light becomes smaller by an angle θ. g ·N is incident on the inclined surface 6. Therefore, the light propagating inside the optical waveguide element 110 no longer satisfies the total internal reflection condition during propagation, such as... Figure 7 The optical axis 17 of the emitted light beam diameter is shown, and it is output from the inclined surface 6 to the outside of the optical waveguide element 110.

[0096] Thus, since a portion of the incident light 10 incident from the cladding 3 is output from the inclined surface 6 to the outside of the optical waveguide element 110, the output light 15 from the exit end face 8 is reduced. On the other hand, since the light optically coupled to the waveguide 2 at the incident end face 7 is output from the exit end face 8 on the waveguide 2 side, the output of the output light 15 is increased by increasing the proportion of light propagating inside the optical waveguide element 110 optically coupled to the waveguide 2. Therefore, by adjusting the positions of the focal points 14 on the X, Y, and Z axes in a manner that maximizes the output measured by the power meter 40, maximum optical coupling can be obtained.

[0097] In the optical waveguide element 110 and optical axis adjustment method described in Embodiment 2, since the component of light propagating inside the optical waveguide element 110 that is not optically coupled to the waveguide 2 is output from the inclined surface 6 to the outside of the optical waveguide element 110, the component that is only optically coupled to the waveguide 2 can be measured by the power meter 40, thus achieving the effect of enabling the incident light 10 to be optically coupled to the waveguide 2 with high efficiency and ease.

[0098] Implementation Method 3

[0099] Figure 8 This is a cross-sectional view showing the state in which the incident light 10 is not optically coupled to the waveguide 2 in the optical waveguide element 120 and optical axis adjustment method according to Embodiment 3.

[0100] exist Figure 8 In the optical waveguide element 120, the waveguide element 120 is composed of the following parts: waveguide 2; cladding 3, which is composed of a lower cladding 3a and an upper cladding 3b that are in contact with the upper and lower surfaces of the waveguide 2; incident end face 7, which is disposed at one end of the optical waveguide element 120 and parallel to the XY plane; exit end face 8, which is disposed at the other end of the optical waveguide element 120; and two inclined surfaces 6, which are respectively disposed at the lower cladding 3a and the upper cladding 3b, sandwiching the waveguide 2 and facing each other, respectively at an inclined angle θ to the XZ plane. g Inclined. Inclined angle θ g The beam is tilted in a direction where the area of ​​the exit end face 8 becomes smaller than the area of ​​the incident end face 7. For the emitted light 15 and the power meter 40, since it is the same as in Embodiment 1, therefore... Figure 8 Omitted in .

[0101] Similar to the optical waveguide element 110 described in Embodiment 2, light incident from the incident end face 7 on the cladding 3 side propagates in a sawtooth pattern between the opposing inclined surfaces 6. However, since the two opposing surfaces of the cladding 3, which sandwich the waveguide 2, are inclined, the angle relative to the normal that decreases with each repeated reflection at each inclined surface 6 becomes twice as large. Therefore, even at the inclined angle θ g In small cases, light propagating inside the optical waveguide element 120 cannot satisfy the total internal reflection condition of the inclined surface 6, such as... Figure 8 The optical axis 17 of the emitted light beam diameter is shown, and it is output from the inclined surface 6 to the outside of the optical waveguide element 120.

[0102] at the tilt angle θ g Even if the length L of the optical waveguide element 120 is shorter than the length of the optical waveguide element 110 in Embodiment 2, the same effect can be obtained when the same angle is used as the optical waveguide element 110 in Embodiment 2.

[0103] Furthermore, even components of light incident on the incident end face 7 with shallow angles are output from the inclined surface 6. Therefore, since the proportion of light output from the exit end face 8 on the cladding 3 side of the light incident on the cladding 3 is reduced, it becomes easier to adjust the position of the focus 14 in order to increase the output measured by the power meter 40.

[0104] In addition to the effects of Embodiment 2, the optical waveguide element 120 and optical axis adjustment method described in Embodiment 3 also achieve the following effects: even at a tilt angle θg Even with a small shape or a short length L of the optical waveguide element 120, the component of the incident light 10 that is not optically coupled to the waveguide 2 can be output from the inclined surface 6. Even the component of the incident light 10 with a shallow angle can be output from the inclined surface 6 to the outside of the optical waveguide element 120, so that the incident light 10 can be optically coupled to the waveguide 2 with high efficiency.

[0105] Implementation Method 4

[0106] Figure 9 This is a schematic diagram showing the optical waveguide element 130 in the optical axis adjustment method according to Embodiment 4.

[0107] exist Figure 9 In the optical waveguide element 130, there are: a waveguide 2 (not shown); a cladding 3 (not shown) consisting of a lower cladding 3a and an upper cladding 3b connected to the upper and lower surfaces of the waveguide 2; an incident end face 7 parallel to the XY plane; and an exit end face 8 opposite to the incident end face 7. The four surfaces of the optical waveguide element 130, excluding the incident end face 7 and the exit end face 8, are composed of inclined surfaces 61. Each inclined surface 61 is inclined at an angle θ in the direction in which the area of ​​the exit end face 8 becomes smaller than the area of ​​the incident end face 7. g Inclined. For the emitted light 15 and the power meter 40, since it is the same as in Embodiment 1, therefore... Figure 9 Omitted in .

[0108] Similar to the optical waveguide element 120 described in Embodiment 3, light incident from the incident end face 7 on the cladding 3 side changes direction due to the tilt angle θ. g The light propagates in a sawtooth pattern between the opposing inclined surfaces 61, and during propagation, the total internal reflection condition is no longer met, resulting in output from the inclined surfaces 61 to the outside of the optical waveguide element 130.

[0109] In the optical waveguide element 130 according to Embodiment 4, there is also an inclined surface 61 opposite to the XZ and YZ directions. That is, the optical waveguide element 130 has a shape in which the width between the two sides of the waveguide 2 and the cladding 3 narrows from the incident end face 7 side to the exit end face 8 side. According to this structure, regardless of whether the light incident from the incident end face 7 on the cladding 3 side is deflected in the X or Y direction, it is output from the inclined surface 61 to the outside of the optical waveguide element 130 during propagation. Therefore, the proportion of light output from the exit end face 8 in the light incident on the cladding 3 is reduced, and it is easier to adjust the focus 14 to maximize the output of the emitted light 15 measured by the power meter 40.

[0110] In addition to the effects of Embodiment 3, the optical waveguide element 130 and optical axis adjustment method described in Embodiment 4 also have the following effects: even if the position shift of the focal point of the incident light 10 occurs in either the Y direction or the X direction, the component of the incident light 10 that is not optically coupled to the waveguide 2 is output from the inclined surface 61 to the outside of the optical waveguide element 130. Therefore, the component of the light propagating inside the optical waveguide element 130 that is optically coupled to the waveguide 2 can be measured by the power meter 40. Thus, it also has the effect of enabling the incident light 10 to be optically coupled to the waveguide 2 with high efficiency.

[0111] Implementation Method 5

[0112] Figure 10 This is a cross-sectional view showing the state in which the optical axis of the incident light 10 in the optical waveguide element 140 is adjusted in the optical waveguide element 140 and optical axis adjustment method according to Embodiment 5.

[0113] exist Figure 10 In this embodiment, the optical waveguide element 140 is composed of the following parts: a waveguide 2; a cladding 3, consisting of a lower cladding 3a and an upper cladding 3b connected to the upper and lower surfaces of the waveguide 2; an incident end face 7, disposed at one end of the optical waveguide element 140 and parallel to the XY plane; an exit end face 8, disposed at the other end of the optical waveguide element 140 and parallel to the XY plane; and a light absorption layer 30, respectively disposed inside the lower cladding 3a and the upper cladding 3b, and parallel to the XZ plane, i.e., parallel to the waveguide 2. Furthermore, a reflecting surface 4 is formed on the lower surface of the lower cladding 3a and the upper surface of the upper cladding 3b. For the emitted light 15 and the power meter 40, since they are the same as in Embodiment 1, therefore... Figure 10 Not shown in the image.

[0114] In the optical waveguide element 140 according to Embodiment 5, light incident from the cladding 3 on the incident end face 7 side is totally reflected at the boundary between the cladding 3 and the external air layer or bonding member, and thus propagates in a sawtooth pattern between the opposing reflecting surfaces 4 of the cladding 3.

[0115] In the optical waveguide element 140 according to Embodiment 5, light absorption layers 30 are respectively disposed inside the lower cladding layer 3a and the upper cladding layer 3b, which are in contact with the upper and lower surfaces of the waveguide 2, in the Y direction. These light absorption layers 30 have the function of absorbing propagating light. Therefore, since the light propagating inside the optical waveguide element 140 is absorbed when passing through the light absorption layer 30, the output of the propagating light decreases each time it passes through the light absorption layer 30.

[0116] As the light propagates in a zigzag pattern between the opposing reflective surfaces 4 of the cladding 3, it passes through the light-absorbing layer 30 multiple times, thereby absorbing most of the light. Therefore, since the proportion of light emitted from the exiting end face 8 on the cladding 3 side of the light incident on the cladding 3 becomes smaller, it becomes easier to adjust the focus 14 in order to maximize the output of the emitted light 15 as measured by the power meter 40.

[0117] In the optical waveguide element 140 and optical axis adjustment method described in Embodiment 5, since light absorption layers 30 are respectively disposed inside the lower cladding layer 3a and the upper cladding layer 3b which are in contact with the upper and lower surfaces of the waveguide 2, the light absorption layers 30 can absorb the components of the incident light 10 that are not optically coupled to the waveguide 2. Therefore, since the component of the light propagating inside the optical waveguide element 140 that is optically coupled to the waveguide 2 can be measured by the power meter 40, the effect of enabling the incident light 10 to be optically coupled to the waveguide 2 with high efficiency is achieved.

[0118] Implementation Method 6

[0119] Figure 11 This is a cross-sectional view showing the state in which the optical axis of the incident light 10 in the optical waveguide element 150 is adjusted in the optical waveguide element 150 and optical axis adjustment method according to Embodiment 6.

[0120] exist Figure 11 In the optical waveguide element 150, the waveguide 2 is composed of the following parts: a waveguide 2; a cladding 3, consisting of a lower cladding 3a and an upper cladding 3b connected to the upper and lower surfaces of the waveguide 2; an incident end face 7, disposed at one end of the optical waveguide element 150 and parallel to the XY plane; an exit end face 8, disposed at the other end of the optical waveguide element 150 and parallel to the XY plane; and a light absorption layer 30, disposed only inside either the lower cladding 3a or the upper cladding 3b, and parallel to the XZ plane. Among these, in... Figure 11 The diagram shows the configuration of the light-absorbing layer 30 disposed within the upper cladding 3b. As for the emitted light 15 and the power meter 40, since they are the same as in Embodiment 1, [the following is also shown]. Figure 11 Not shown in the image.

[0121] Similar to the optical waveguide element 140 of Embodiment 5, in the optical waveguide element 150 of Embodiment 6, light incident from the cladding 3 on the incident end face 7 side also propagates in a sawtooth pattern between the opposing reflecting surfaces 4 of the cladding 3, and is absorbed each time it passes through the light absorption layer 30 during propagation.

[0122] In the optical waveguide element 150 according to Embodiment 6, since the light absorption layer 30 is disposed only inside either the lower cladding layer 3a or the upper cladding layer 3b, the construction of the optical waveguide element 150 is simplified, and the optical waveguide element 150 can be easily manufactured.

[0123] Furthermore, since the light absorption layer 30 is disposed only inside either the lower cladding layer 3a or the upper cladding layer 3b, the efficiency of absorbing light propagating in the cladding layer 3 of the optical waveguide element 150 may be reduced compared to the case where the light absorption layer 30 is disposed inside both the lower cladding layer 3a and the upper cladding layer 3b, as in the case of the optical waveguide element 140 according to Embodiment 5.

[0124] As a countermeasure to reduce the efficiency of light absorption, the length L of the optical waveguide element 150 can be increased to improve the proportion of light absorbed when passing through the light absorption layer 30. Alternatively, the thickness of the light absorption layer 30 in the Y direction inside the cladding 3 can be increased, thereby increasing the length of light propagating inside the optical waveguide element 150 that passes through the light absorption layer 30, i.e., the light absorption length. Furthermore, the concentration of light-absorbing components contained in the light absorption layer 30 can be increased to improve the light absorption rate.

[0125] Based on the above structure, by propagating in a sawtooth pattern between the opposing cladding 3 reflective surfaces 4 and passing through the light-absorbing layer 30 multiple times, most of the light propagating inside the cladding 3 of the optical waveguide element 150 is absorbed. Therefore, the proportion of light incident on the cladding 3 that exits from the exiting end face 8 on the cladding 3 side is reduced, making it easier to adjust the focus 14 to maximize the output of the emitted light 15 measured by the power meter 40.

[0126] In the optical waveguide element 150 and optical axis adjustment method described in Embodiment 6, since the light absorption layer 30 is disposed only inside either the lower cladding layer 3a or the upper cladding layer 3b that are in contact with the upper and lower surfaces of the waveguide 2, the light absorption layer 30 can absorb the components of the incident light 10 that are not optically coupled to the waveguide 2. Therefore, since the component of the light propagating inside the optical waveguide element 150 that is optically coupled to the waveguide 2 can be measured by the power meter 40, in addition to enabling the incident light 10 to be optically coupled to the waveguide 2 with high efficiency and ease, the structure of the optical waveguide element 150 can be simplified, and the optical waveguide element 150 can also be manufactured at low cost.

[0127] Implementation Method 7

[0128] Figure 12 This is a cross-sectional view of the optical waveguide element 160 and the light guide plate 21 in the optical axis adjustment method according to Embodiment 7.

[0129] exist Figure 12 In the optical waveguide element 160, the waveguide 2 is composed of the following parts: waveguide 2; cladding 3, which is composed of a lower cladding 3a and an upper cladding 3b that are in contact with the upper and lower surfaces of the waveguide 2; incident end face 7, which is disposed at one end of the optical waveguide element 160 and is parallel to the XY plane; and exit end face 8, which is disposed at the other end of the optical waveguide element 160 and is parallel to the XY plane.

[0130] The light guide plate 21 is disposed with its lower surface in contact with the refractive index matching member 20, which is configured to be in contact with the upper surface of the upper cladding 3b of the optical waveguide element 160, and a rough surface 22 is formed on the upper surface. For the emitted light 15, the power meter 40, and the imaging element 41, since it is the same as in Embodiment 1, ... Figure 12 Not shown in the image.

[0131] The refractive index matching component 20 is composed of a component having the same refractive index as the cladding 3 and the light guide plate 21. As an example of the refractive index matching component 20, a liquid component such as matching oil can be cited. When adjusting the optical coupling of the incident light 10 to the waveguide 2, the refractive index matching component 20 is not fixed to either the cladding 3 or the light guide plate 21. That is, the refractive index matching component 20 contacts the upper cladding 3b and the light guide plate 21 in a form that can be easily peeled off. In other words, the light guide plate 21 is mounted to the optical waveguide element 160 in a detachable form by peeling off the refractive index matching component 20.

[0132] Light incident from the incident end face 7 on the cladding 3 side, propagating at an angle to the upper surface along the Y-axis, is incident on the refractive index matching member 20. Additionally, light propagating at an angle to the lower surface along the Y-axis undergoes total internal reflection at the reflecting surface 4 of the lower cladding 3a, and then changes angle towards the upper surface along the Y-axis before incidenting on the refractive index matching member 20.

[0133] Since the cladding 3, the refractive index matching component 20, and the light guide plate 21 have the same refractive index, they do not reflect or have low reflectivity at their respective interfaces, thus transmitting most of the light. Light incident on the light guide plate 21 is directed onto the rough surface 22 of the light guide plate 21, whereby a portion of the light is scattered upwards along the Y-axis as scattered light 18 and output to the outside of the optical waveguide element 160, while the remaining portion is reflected. The reflected light propagates while being reflected in a sawtooth pattern between the reflecting surface 4 and the rough surface 22 of the light guide plate 21. Thus, by using the same method as the optical axis adjustment method for the optical waveguide element 100 described in Embodiment 1, and employing the power meter 40 and the imaging element 41, the incident light 10 can be easily and efficiently optically coupled to the waveguide 2.

[0134] Since the light guide plate 21 with the roughened surface 22 and the refractive index matching component 20 are not fixed to the optical waveguide element 160, the light guide plate 21 and the refractive index matching component 20 can be removed after the adjustment of the optical coupling with the waveguide 2 is completed. That is, the light guide plate 21 can be said to be detachable.

[0135] When the refractive index matching component 20 is a liquid component such as matching oil, the refractive index matching component 20 remaining on the optical waveguide element 160 can be wiped with an organic component after the light guide plate 21 is removed. Examples of such organic components include ethanol or acetone, but are not limited to these components. After the adjustment of optical coupling with the waveguide 2 is completed, the light guide plate 21 removed from the optical waveguide element 160 can be repeatedly reused to obtain optical coupling with other optical waveguide elements 160.

[0136] Furthermore, the above description outlines the configuration in which the light guide plate 21 is removed after the adjustment to achieve optical coupling with waveguide 2 is completed. However, it is also possible to remove the light guide plate 21 while maintaining its position after adjustment. Figure 12 The structure consisting of the optical waveguide element 160 shown and the light guide plate 21 mounted on the optical waveguide element 160 via the refractive index matching component 20 is used as a single optical waveguide element.

[0137] The upper surface of the upper cladding 3b on the side of the optical waveguide element 160 connected to the refractive index matching component 20 does not need to be processed into a rough surface that generates scattered light when light is incident from the inside of the cladding 3. Therefore, since the structure of the optical waveguide element 160 is simplified, the optical waveguide element 160 can be easily manufactured, and a general-purpose optical waveguide element 160 without a rough surface can also be used.

[0138] In addition to the effects of Embodiment 1, the optical waveguide element 160 and the light guide plate 21 described in Embodiment 7 also have the following effects: Since the light guide plate 21 can be removed after the optical axis is adjusted, it can be reused repeatedly. Furthermore, since the optical waveguide element 160 without a rough surface can be used, optical coupling to the waveguide 2 of the optical waveguide element 160 can be achieved at low cost, and the optical waveguide element 160 can be manufactured at low cost.

[0139] Implementation Method 8

[0140] Figure 13 This is a cross-sectional view of the light waveguide element 160 and the light guide plate 23 in the light guide plate 23 and the light axis adjustment method according to Embodiment 8.

[0141] exist Figure 13In order to prevent light incident from the incident end face 7 on the cladding 3 side from irradiating the upper surface side opposite the refractive index matching component 20, the light guide plate 23 has a large height (thickness) in the Y direction. In other words, the light guide plate 23 has a thick layer. The same applies to the optical waveguide element 160, the emitted light 15, and the power meter 40 as in embodiment 7.

[0142] Light incident from the incident end face 7 on the cladding 3 side passes through the refractive index matching component 20 and is then incident on the light guide plate 23. Here, the length of the light guide plate 23 in the Z direction is set as L. G Let the incident beam angle of the incident light be θ. in When the refractive indices of the cladding 3, the refractive index matching component 20, and the light guide plate 23 are respectively set to n, the height (thickness) H of the light guide plate 23 is set in a manner that satisfies the following equation (2). G1 .

[0143] [Equation 2]

[0144]

[0145] H is set by satisfying equation (2) G1 Therefore, the light incident on the light guide plate 23 through the refractive index matching component 20 does not incident on the upper surface of the light guide plate 23 opposite to the refractive index matching component 20. Thus, the incident light always propagates away from the optical waveguide element 160 in the Y direction. Therefore, the light incident on the light guide plate 23 through the refractive index matching component 20 is output from the XY plane of the light guide plate 23, that is, the end face 8 of the optical waveguide element 160 of the light guide plate 23.

[0146] The output light follows Snell's law, and the angle in the θX direction is tilted towards the Y direction, causing the light to propagate away from the optical waveguide element 160 in the Y direction. Therefore, the light propagating in the light guide plate 23 is output sufficiently far away in the Y direction from the outgoing light 15 that is optically coupled to the waveguide 2 and output from the exit facet 8 on the waveguide 2 side. That is, the light propagating in the light guide plate 23 is spatially separated from the outgoing light 15. Therefore, since the power meter 40 can selectively measure only the output of the outgoing light 15, it is possible to adjust the lens and the light source (neither shown) to maximize optical coupling.

[0147] Furthermore, although the length L of the light guide plate 23 G Preferably, the length L of the light guide plate 23 is the same as that of the optical waveguide element 160. However, since the light incident from the cladding 3 to the light guide plate 23 via the refractive index matching component 20 is closer to the incident end face 7 side in the Z direction than the exit end face 8 side, the length L of the light guide plate 23 is... G It can also be shorter than the length L of the optical waveguide element 160.

[0148] Thus, according to the light guide plate 23 and the optical axis adjustment method according to Embodiment 8, since it is not necessary to process a rough surface on the light guide plate 23 in order to generate scattered light, the structure of the light guide plate 23 becomes simple, thereby achieving the effect of obtaining a light guide plate 23 that can be easily manufactured.

[0149] In addition to the effects of embodiment 7, the light guide plate 23 and the optical axis adjustment method described in embodiment 8 can also achieve the following effects: Since a light guide plate 23 without rough surfaces can be used, optical coupling to the waveguide 2 of the optical waveguide element 160 can be achieved at low cost, and a light guide plate 23 that can be manufactured at low cost can be obtained.

[0150] Implementation Method 9

[0151] Figure 14 This is a cross-sectional view showing the optical waveguide element 160 and the light guide plate 23 in the optical axis adjustment method according to Embodiment 9.

[0152] like Figure 14 As shown, a reflector 24 is disposed on the XY plane of the light guide plate 23 on the emitting end face 8 side. The reflector 24 functions as follows: when light propagating inside the light guide plate 23 shines on the reflector 24, it reflects the light inside the light guide plate 23. The optical waveguide element 160, the emitted light 15, the refractive index matching component 20, and the power meter 40 are the same as in embodiment 8.

[0153] Light incident from the incident end face 7 on the cladding 3 side and passing through the refractive index matching component 20 onto the light guide plate 23 is totally reflected on the upper surface of the light guide plate 23 opposite to the refractive index matching component 20. However, since a reflector 24 is disposed on the end face of the light waveguide element 160 on the XY plane of the light guide plate 23, i.e., the end face of the light waveguide element 160 on the light guide plate 23, the light is not output from the end face of the light guide plate 23 on the end face of the light waveguide element 160.

[0154] The light reflected by the mirror 24 passes between the light guide plate 23, the refractive index matching component 20, and the optical waveguide element 160, and is finally output from the surface of the output end face 8 of the optical waveguide element 160. Therefore, since only the output of the emitted light 15 can be measured in the power meter 40, the lens and the light source (neither shown) can be adjusted to maximize the optical coupling.

[0155] Because a reflector 24 is disposed on the end face of the light guide plate 23 on the exit end face 8 side, the height (thickness) H of the light guide plate 23 is... G2 It can also be low, for example, it can be the height (thickness) H of the light guide plate involved in embodiment 8. G1 Half of that. That is, when the length of the light guide plate 23 in the Z direction according to Embodiment 9 is set to L.G Let the incident beam angle of the incident light be θ. in If the refractive indices of the cladding 3, the refractive index matching component 20, and the light guide plate 23 are all set to the same refractive index n, the height (thickness) H of the light guide plate 23 can be set in a manner that satisfies the following equation (3). G2 That's all.

[0156] [Formula 3]

[0157]

[0158] The reflector 24 can also be composed of a dielectric multilayer film, a dielectric single-layer film, or a metal film.

[0159] Thus, according to the light guide plate 23 and the optical axis adjustment method involved in Embodiment 9, by arranging the reflector 24 on the light guide plate 23, the light incident on the cladding 3 of the optical waveguide element 160 and the light incident on the waveguide 2 can be separated more accurately.

[0160] In addition to the effects of embodiment 8, the light guide plate 23 and the optical axis adjustment method described in embodiment 9 can more accurately separate the light incident on the cladding 3 and the light incident on the waveguide 2 in space, thus making it easier to obtain optical coupling of the waveguide 2 toward the optical waveguide element 160. Furthermore, since the light guide plate 23 can be configured to be small, it can also be manufactured at low cost.

[0161] Although various exemplary embodiments and examples are described in this disclosure, the various features, forms and functions described in one or more embodiments are not limited to the application of a specific embodiment, and can also be applied to the embodiment alone or in various combinations.

[0162] Therefore, numerous variations not illustrated can be conceived within the scope of the technology disclosed in this application. These include variations, additions, or omissions of at least one constituent element, as well as the extraction of at least one constituent element and its combination with constituent elements of other embodiments.

[0163] Explanation of reference numerals in the attached figures

[0164] 1a...Light source; 1b...Lens; 2...Waveguide; 3...Cladding; 4...Reflecting surface; 5, 22...Rough surface; 6, 61...Sloping surface; 7...Incident end face; 8...Outgoing end face; 10...Incident light; 11...Main axis of incident light; 12...Optical axis of incident light beam diameter; 13...Part of incident light; 14...Focus point; 15...Outgoing light; 16...Main axis of outgoing light; 17...Optical axis of outgoing light beam diameter; 18...Scattered light; 20...Refractive index matching component; 21, 23...Light guide plate; 24...Mirror; 30...Light absorption layer; 40...Power meter; 41...Image capturing element; 50, 100, 110, 120, 130, 140, 150, 160...Optical waveguide element.

Claims

1. An optical waveguide element, characterized in that, The optical waveguide element comprises: Waveguide, used to propagate light; The cladding consists of an upper cladding whose lower surface is in contact with one side of the waveguide, and a lower cladding whose upper surface is in contact with the other side of the waveguide; Both sides are provided on both sides of the upper and lower cladding layers; An incident end face is disposed at one end of the waveguide and the cladding; and The exit facet is located at the other end of the waveguide and the cladding. The upper surface of the forming plane of the upper cladding and the lower surface of the forming plane of the lower cladding are inclined relative to the waveguide, and the other is parallel to the waveguide. The thickness of the cladding in the direction perpendicular to the waveguide is thinner on the exit end face side than on the incident end face side. The distance between the upper surface of the forming plane of the upper cladding and the lower surface of the forming plane of the lower cladding gradually decreases from the incident end face to the exit end face.

2. An optical waveguide element, characterized in that, The optical waveguide element comprises: Waveguide, used to propagate light; The cladding consists of an upper cladding whose lower surface is in contact with one side of the waveguide, and a lower cladding whose upper surface is in contact with the other side of the waveguide; Both sides are provided on both sides of the upper and lower cladding layers; An incident end face is disposed at one end of the waveguide and the cladding; and The exit facet is located at the other end of the waveguide and the cladding. The upper surface of the forming plane of the upper cladding and the lower surface of the forming plane of the lower cladding form inclined surfaces relative to the waveguide. The thickness of the cladding in the vertical direction of the waveguide is thinner on the exit end face side than on the incident end face side. The distance between the upper surface of the forming plane of the upper cladding and the lower surface of the forming plane of the lower cladding gradually decreases from the incident end face to the exit end face.

3. The optical waveguide element according to claim 2, characterized in that, The tilt angle θg between the tilted surface formed by the upper surface of the upper cladding forming plane and one side of the waveguide, and the tilt angle θg between the tilted surface formed by the lower surface of the lower cladding forming plane and the other side of the waveguide are equal.

4. The optical waveguide element according to claim 3, characterized in that, The two sides of the waveguide and the two sides of the cladding forming plane are inclined surfaces that are inclined at an angle θg relative to the principal axis of the incident light as they move from the incident end face to the exit end face.

5. A method for adjusting the optical axis, characterized in that, include: The step of focusing light from a light source onto the incident end face of the optical waveguide element according to any one of claims 1 to 4 using a lens; The steps of measuring the output emitted from the exit facet of the optical waveguide element using a power meter; and The step of increasing the output is to adjust the focal position and incident beam angle of the focused incident light by adjusting the position and angle of either or both of the light source and the lens.

Images