Optical devices and optical systems

Abstract

The present application provides a kind of optical device and optical system, which can properly irradiate reflected light from an irradiated body to a magnetic element with simple structure without high-precision optical axis adjustment.The optical device (1A) comprises at least one magnetic element (30) having a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first and second ferromagnetic layers; a laser diode (11, 12, 13, 14) emitting laser light; and a waveguide (20). The waveguide (20) has at least one light entrance port (21i, 22i, 23i, 24i) for the laser light of the laser diode (11, 12, 13, 14) to enter, and a light exit port (27o) for the light to exit to the outside, and the at least one magnetic element (30) is disposed in the vicinity of the light exit port (27o).

Description

Technical Field

[0001] This disclosure relates to optical devices and optical systems. Background Technology

[0002] Lasers are widely used in various fields such as industry, medicine, and communications. In particular, laser diodes that emit laser light are packaged and commercially available, with can packaging and butterfly packaging being known as representative packaging forms.

[0003] In recent years, XR glasses, such as AR (Augmented Reality) glasses and VR (Virtual Reality) glasses, have been anticipated as small wearable devices. In XR glasses, miniaturizing the various components to fit within the size of typical eyeglasses is crucial. In this context, there is increased interest in small planar lightwave circuits (PLCs) using laser diodes. Furthermore, there is a growing expectation for optical modulators using materials with electro-optic effects that form optical waveguides, and in particular, for optical modulators incorporating optical modulation elements using lithium niobate films.

[0004] Patent Document 1 discloses an optical device comprising an optical modulation element using a lithium niobate film and multiple laser diodes. The optical modulation element has a waveguide and multiple magnetic elements. The multiple laser diodes include near-infrared lasers for eye-tracking applications. Near-infrared light emitted from the near-infrared laser is incident on a light inlet at one end of the waveguide and propagates within the waveguide, exiting from a light outlet at the other end of the waveguide to irradiate a target. A portion of the reflected light, after being reflected by the target, returns from the light outlet back into the waveguide and reaches the magnetic elements via a monitoring waveguide connected to the waveguide. The magnetic elements measure the intensity of the reflected light returning via the monitoring waveguide, thereby detecting the state of the target's eyeball (pupil position, fixation point, etc.).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2022-155468 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] In the optical device disclosed in Patent Document 1, in order to return reflected light from the irradiated object to the waveguide, it is necessary to adjust the optical axis between the optical axis of the reflected light and the optical axis of the waveguide's light exit port (waveguide coupling). However, this optical axis adjustment requires high-precision adjustment of the angle and position of the optical axis, which makes it difficult to ensure that the reflected light returns properly to the waveguide. Moreover, due to the propagation loss generated in the waveguide and the monitoring waveguide, the intensity of the reflected light is reduced, resulting in insufficient light intensity for measuring the intensity of the reflected light when irradiating the magnetic element.

[0010] This disclosure was made in view of the above-mentioned problems, and its object is to provide an optical device and optical system that does not require high-precision optical axis adjustment and can properly irradiate a magnetic element with reflected light from an irradiated object using a simple structure.

[0011] Solution for solving the problem

[0012] To address the aforementioned problems, the optical device disclosed herein is characterized by comprising: at least one magnetic element having a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer; a laser diode emitting laser light; and a waveguide having at least one light inlet for the laser light from the laser diode to enter and a light outlet for the laser light to exit to the outside, wherein the at least one magnetic element is disposed near the light outlet.

[0013] To solve the above problems, the optical system disclosed herein is characterized in that it comprises: the aforementioned optical device; and an optical system that guides the laser emitted by the optical device to the irradiated object.

[0014] The effects of the invention

[0015] This disclosure provides an optical device and system that does not require high-precision optical axis adjustment and can, with a simple structure, properly direct reflected light from an irradiated object onto a magnetic element. Attached Figure Description

[0016] Figure 1 This is a top view schematic diagram of the optical device according to the first embodiment of this disclosure.

[0017] Figure 2 It is along Figure 1 A cross-sectional view along line AA.

[0018] Figure 3 It means Figure 1 A three-dimensional view of the vicinity of the magnetic component.

[0019] Figure 4 It means Figure 1A top view of the vicinity of the magnetic element.

[0020] Figure 5 It is along Figure 1 A cross-sectional view of the BB line.

[0021] Figure 6 It is along Figure 1 A cross-sectional view of the CC line.

[0022] Figure 7 It is a local magnification Figure 5 A diagram of the periphery of the magnetic component.

[0023] Figure 8 This is a cross-sectional view showing the magnetic element of the optical device in the first embodiment of this disclosure.

[0024] Figure 9 This is a diagram illustrating the first mechanism of operation related to the magnetic element of the optical device in the first embodiment of this disclosure.

[0025] Figure 10 This is a diagram illustrating the second mechanism of operation related to the magnetic element of the optical device in the first embodiment of this disclosure.

[0026] Figure 11 This is a perspective view showing the vicinity of the magnetic element of the optical device in the second embodiment of this disclosure.

[0027] Figure 12 It means Figure 11 A top view of the vicinity of the magnetic element.

[0028] Figure 13 It means Figure 11 A cross-sectional view near the magnetic element.

[0029] Figure 14 This is a perspective view showing the vicinity of the magnetic element of the optical device in the third embodiment of this disclosure.

[0030] Figure 15 It means Figure 14 A top view of the vicinity of the magnetic element.

[0031] Figure 16 It means Figure 14 A cross-sectional view near the magnetic element.

[0032] Figure 17 This is a perspective view showing the vicinity of the magnetic element of the optical device in the fourth embodiment of this disclosure.

[0033] Figure 18 It means Figure 17 A cross-sectional view near the magnetic element.

[0034] Figure 19 This is a perspective view showing the vicinity of the magnetic element of the optical device in the fifth embodiment of this disclosure.

[0035] Figure 20 It means Figure 19 A cross-sectional view near the magnetic element.

[0036] Figure 21 This is a top view schematic diagram of the optical device according to the sixth embodiment of this disclosure.

[0037] Figure 22 yes Figure 21 A top view of the optical modulation section.

[0038] Figure 23 This is a conceptual diagram of the publicly disclosed optical system.

[0039] Figure 24 This is a top view schematic diagram of the optical device in a derivative example of this disclosure.

[0040] Explanation of reference numerals in the attached figures

[0041] 1A, 1B, 1C, 1D, 1E, 1F, 1G, optical devices; 10A, 10B, 10C, 10D, 10E, 10F, 10G, optical waveguide elements; 10o, light exit surface; 11, 12, 13, 14, laser diodes; 20, 90, waveguides; 21, 22, 23, 24, input waveguides; 21i, 22i, 23i, 24i, 90i, light entrances; 25, first wave combiner; 26, second wave combiner; 2 7. Output waveguide; 27°, 90°, light exit port; 28. Substrate; 29. ​​Cladding; 30. Magnetic element; 31. First ferromagnetic layer; 32. Second ferromagnetic layer; 33. Spacer layer; 34. Third ferromagnetic layer; 35. Magnetic coupling layer; 36. Base layer; 37. Vertical magnetization induced layer; 38. Capping layer; 39. Sidewall insulating layer; 41. Upper electrode; 42. Lower electrode; 43, 44, 47. Path wiring; 45. Pin. Input terminal; 46, Pout, Output terminal; 48, Input / output terminal; 50, Reflector; 51, Tilted surface; 60, Optical modulation section; 70, Mach-Zehnder waveguide; 71, Upstream waveguide; 72, Wavelength splitter; 73, First waveguide; 74, Second waveguide; 75, Wavelength combiner; 76, Downstream waveguide; 81, 82, 83, 84, PS, Electrode; 85, 86, Power supply; 87, Terminating resistor; 100, Optical system; 11 0. Light source module; 120. Optical system; 121. Collimating lens; 122. Slit; 123. ND filter; 124. Optical scanning mirror; 130. Laser driver; 140. Optical scanning mirror driver; 150. Video controller; 200. XR glasses; 201. Frame; 202. Lens; E. Illuminated object; G. Earth; LE. Outgoing light; LR. Reflected light; M31, M32, M34. Magnetization; PG. Reference potential terminal. Detailed Implementation

[0042] Hereinafter, embodiments of the present disclosure will be described in detail with appropriate reference to the accompanying drawings. In the following description, the drawings sometimes show enlarged portions of characteristic features for ease of understanding, and the dimensions, ratios, etc., of the constituent elements may differ from actual dimensions. The materials, dimensions, etc., illustrated in the following description are merely examples. The present disclosure is not limited to such examples and can be implemented with appropriate modifications within the scope of achieving the effects of the present disclosure. Furthermore, the term "~" indicating a numerical range refers to any value within a range including the values ​​described before and after it as a lower and upper limit value.

[0043] [First Embodiment]

[0044] The first embodiment of this disclosure will now be described.

[0045] First, refer to Figure 1The structure of the optical device 1A in the first embodiment of this disclosure will be described. Figure 1 This is a top view of the optical device 1A in the first embodiment.

[0046] Figure 1 The optical device 1A shown has multiple laser diodes 11, 12, 13, 14, an optical waveguide element 10A, and a magnetic element 30.

[0047] In this specification, within the orthogonal xyz coordinate system defined in the figures, the direction along one side of the optical waveguide element 10A is defined as the x-direction, the direction orthogonal to the x-direction is defined as the y-direction, and the direction orthogonal to both the x and y directions is defined as the z-direction. The x-direction is the length direction of the optical waveguide element 10A. The y-direction is the width direction of the optical waveguide element 10A. The z-direction is the direction perpendicular to the main surface of the optical waveguide element 10A. Hereinafter, the orientation will be further considered, and terms such as "positive z-direction" and "negative z-direction" will be used. In particular, the "positive z-direction" will sometimes be referred to as "up" and the "negative z-direction" as "down." Furthermore, the z-direction, as the up / down direction, is not necessarily aligned with the direction of gravity.

[0048] Laser diodes 11, 12, 13, and 14 are configured to emit lasers in different wavelength ranges. Laser diodes 11, 12, 13, and 14 can be provided by an integrated light source module. Laser diodes 11, 12, 13, and 14 can also be mounted on the upper surface of the subcarrier, for example, as bare chips. In this case, the subcarrier and the substrate 28 of the optical waveguide element 10A (see, for example, reference...) Figure 2 Laser diodes 11, 12, 13, and 14 can be fixed relative to optical waveguide element 10A by bonding via a metal bonding layer or the like.

[0049] Laser diode 11 is, for example, a red laser source that emits laser light (red light) in the wavelength range of 590nm to 800nm. Laser diode 12 is, for example, a green laser source that emits light (green light) in the wavelength range of 490nm and above but less than 590nm. Laser diode 13 is, for example, a blue laser source that emits light (blue light) in the wavelength range of 380nm and above but less than 490nm. Laser diode 14 is, for example, a near-infrared laser source that emits laser light (near-infrared light) in the wavelength range of 780nm to 2500nm. There is no particular limitation on the arrangement order or number of laser diodes 11, 12, 13, and 14 that emit light in each wavelength range.

[0050] Laser diodes 11, 12, and 13 emit visible light in the three primary colors (red, green, and blue), respectively. By superimposing these emitted lights based on the principle of additive color mixing, the desired color can be represented. Laser diodes 11, 12, and 13 can also emit light in colors other than the three primary colors.

[0051] Visible light is used, for example, for image display. To achieve the desired color representation by overlapping different colors of light, it is preferable to appropriately adjust the intensity of each color. For example, the intensity of the emitted light from laser diodes 11, 12, and 13 can be appropriately controlled. Alternatively, as described in the sixth embodiment described later, an optical modulation unit can be provided within the optical waveguide element 10A, and optical modulation can be performed within the optical waveguide element 10A.

[0052] The laser diode 14 emits near-infrared light. Near-infrared light is used, for example, in eye-tracking applications.

[0053] A waveguide 20 for propagating light is formed in the optical waveguide element 10A. For example... Figure 1 As shown, waveguide 20 is composed of, for example, input waveguides 21, 22, 23, 24, a first wave combiner 25, a second wave combiner 26, and an output waveguide 27.

[0054] At the ends of input waveguides 21, 22, 23, and 24 are optical entrance ports 21i, 22i, 23i, and 24i, respectively, for the lasers emitted from laser diodes 11, 12, 13, and 14. These optical entrance ports 21i, 22i, 23i, and 24i are optical input ports. Each input waveguide 21, 22, 23, and 24 is optically connected to laser diodes 11, 12, 13, and 14, respectively. The optical axes of the lasers emitted from laser diodes 11, 12, 13, and 14 are adjusted so that they are appropriately incident into their corresponding optical entrance ports 21i, 22i, 23i, and 24i.

[0055] Input waveguides 21, 22, and 23 converge at the first multiplexing section 25 and connect to the output waveguide 27. Lasers incident on the light entrances 21i, 22i, and 23i propagate in the input waveguides 21, 22, and 23, respectively, and are combined by the first multiplexing section 25. Here, the structure is such that the input waveguides 21, 22, and 23 converge at the first multiplexing section 25, but it can also be configured with multiple multiplexing sections, for example, where the input waveguides 21 and 22 converge and then the input waveguides 23 further converge.

[0056] The light combined by the first combining section 25 propagates in the output waveguide 27 and is emitted as light LE from the light exit port 27o formed at the end of the output waveguide 27. The light exit port 27o is the light output port. The light exit port 27o is provided on one side of the optical waveguide element 10A. In this specification, the side of the optical waveguide element 10A with the light exit port 27o is referred to as the light emitting surface 10o.

[0057] The input waveguide 24 is connected to the output waveguide 27 via the second combiner 26. Laser light incident from the laser diode 14 onto the light entrance 24i propagates in the input waveguide 24 and then propagates in the output waveguide 27 via the second combiner 26. The light propagating in the output waveguide 27 continues to propagate within the output waveguide 27 and is emitted as outgoing light LE from the light exit port 27o formed at the end of the output waveguide 27. Near-infrared light propagating in the input waveguide 24 can also be combined with visible light propagating in the input waveguides 21, 22, and 23 via the second combiner 26.

[0058] The emitted light LE from the light exit port 27o is guided by a MEMS mirror or similar means to reach the irradiated object E. The irradiated object E is, for example, the human eye. The emitted light LE is reflected by the irradiated object E. The reflected light LR, after being reflected by the irradiated object E, travels in the opposite direction along the same optical path as the emitted light LE, returning to the vicinity of the light exit port 27o. The reflected light LR irradiates the light emitting surface 10o, which includes the vicinity of the light exit port 27o. Figure 1 The diagram schematically illustrates the emitted light LE, the reflected light LR, and the irradiated object E.

[0059] like Figure 1 As shown, the magnetic element 30 is positioned near the light exit port 27o of the optical waveguide element 10A. Reflected light LR irradiates the magnetic element 30 positioned near the light exit port 27o. Thus, the magnetic element 30 can receive the reflected light LR and measure its intensity.

[0060] The magnetic element 30, for example, is used in eye tracking, functioning as a photosensor to detect the intensity of near-infrared light. Near-infrared light emitted from the laser diode 14 propagates through the light entrance 24i in the waveguide 20 and exits from the light exit 27o as the outgoing light LE. In eye tracking, the direction of gaze can be detected by illuminating the human eye with near-infrared light and measuring the intensity of its reflected light LR (corneal reflection). Furthermore, in addition to the measurement results of the reflected light LR intensity, measurement results from other sensors can be combined to detect the direction of gaze with higher accuracy.

[0061] Reference Figure 2 The cross-section of the optical waveguide element 10A of the optical device 1A in the first embodiment will be described. Figure 2 It is along Figure 1 A cross-sectional view along line AA.

[0062] like Figure 2As shown, in the optical waveguide element 10A of the optical device 1A, a waveguide 20 is formed on a substrate 28. The waveguide 20 and the upper surface of the substrate 28 can be in contact with each other or separated. The waveguide 20 can be formed, for example, as a layer disposed on the substrate 28. Here, the waveguide 20 is arranged to protrude from the upper surface of the substrate 28 in the positive z-direction. However, the shape of the waveguide 20 and its formation method are not particularly limited.

[0063] Waveguide 20 is covered by cladding 29. Figure 2 The diagram shows the cross-sections of the input waveguides 21, 22, 23, and 24, but the waveguides 20 in other locations are also formed on the substrate 28 and covered by the cladding 29.

[0064] From the viewpoint of improving light propagation efficiency by confining light within waveguide 20, the material of substrate 28 is preferably a material with a lower refractive index than that of waveguide 20. For example, materials containing aluminum oxide, particularly sapphire, can be used as the material of substrate 28.

[0065] The material used to form the layer of waveguide 20 is preferably a material with a higher refractive index than the substrate 28. Alternatively, materials exhibiting electro-optic effects can be used as the material for forming the layer of waveguide 20; for example, materials containing lithium niobate as a main component can be used.

[0066] The material of cladding 29 can be appropriately selected to match the materials of waveguide 20 and substrate 28. Preferably, the material of cladding 29 is a material with a lower refractive index than waveguide 20 and good light transmittance. Examples of materials that can be used as the material of cladding 29 include SiO2, Al2O3, MgF2, La2O3, ZnO, HfO2, MgO, Y2O3, CaF2, In2O3, or mixtures thereof. However, the materials of waveguide 20, substrate 28, and cladding 29 are not limited to the examples described above.

[0067] Reference Figures 3-6 The magnetic element 30 of the optical device 1A of the first embodiment will be described. Figure 3 It means Figure 1 A three-dimensional view of the vicinity of the magnetic element 30. Figure 4 It means Figure 1 A top view of the vicinity of the magnetic element 30. Figure 5 It is along Figure 1 A cross-sectional view along the BB line. Figure 5 The figure shows the cross-section of the magnetic element 30 in the zx plane. Figure 6 It is along Figure 1 A cross-sectional view along the CC line. Figure 6 The figure shows the cross-section of the magnetic element 30 in the yz plane.

[0068] like Figures 3-6As shown, the magnetic element 30 is disposed near the light emission port 27o of the optical waveguide element 10A. The magnetic element 30 is disposed above the substrate 28. Here, the magnetic element 30 is disposed within the cladding 29 covering the waveguide 20, and the magnetic element 30 is incorporated into the optical waveguide element 10A and cannot be separated from it.

[0069] Although the illustration is omitted, in the optical device 1A, the magnetic element 30 may also be provided at a location other than near the light emission port 27o of the optical waveguide element 10A. That is, the optical device 1A may also have multiple magnetic elements, forming a structure in which at least one magnetic element 30 is disposed near the light emission port 27o. Other magnetic elements may be used for other purposes, such as white balance adjustment of visible light.

[0070] like Figures 3-6 As shown, the magnetic element 30 is positioned offset from the waveguide 20. More specifically, the magnetic element 30 is positioned differently from the waveguide 20 in either the height or width direction to prevent light propagating in the waveguide 20 from illuminating the magnetic element 30. Preferably, the magnetic element 30 is configured separately from the waveguide 20 to prevent light leaking from the waveguide 20 from reaching the magnetic element 30.

[0071] like Figures 3-6 As shown, the magnetic element 30 is electrically connected to the upper electrode 41, the lower electrode 42, the path wiring 43, 44, the input terminal 45, and the output terminal 46.

[0072] The upper electrode 41 and the lower electrode 42 are made of a conductive material. The upper electrode 41 and the lower electrode 42 are, for example, plate-shaped members made of a conductive material, and are arranged opposite each other across the magnetic element 30. The upper electrode 41 is connected to a first surface of the magnetic element 30. The lower electrode 42 is connected to a second surface of the magnetic element 30. Hereinafter, the first surface of the magnetic element 30 located on the side of the upper electrode 41 is sometimes referred to as the upper surface, and the second surface of the magnetic element 30 located on the side of the lower electrode 42 is sometimes referred to as the lower surface. The upper and lower surfaces of the magnetic element 30 are opposite each other in the stacking direction of the magnetic element 30.

[0073] Materials for the upper electrode 41 and the lower electrode 42 can include metals such as Cu, Al, Au, or Ru. Ta or Ti can also be stacked on top of these metals. Furthermore, Cu and Ta laminates, Ta, Cu and Ti laminates, Ta, Cu and TaN laminates, and TiN or TaN can also be used as the upper electrode 41 and the lower electrode 42.

[0074] The upper electrode 41 and the lower electrode 42 may also be transparent to the wavelength range of light irradiated onto the magnetic element 30. For example, the upper electrode 41 and the lower electrode 42 may also be transparent electrodes made of transparent electrode materials containing oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and indium gallium zinc oxide (IGZO). The upper electrode 41 and the lower electrode 42 may also be configured to have a structure containing multiple columnar metals within these transparent electrode materials.

[0075] The path wiring 43 connects the input terminal 45 to the upper electrode 41 or the lower electrode 42. The input terminal 45 is correspondingly provided with the path wiring 43. Here, as an example, two path wirings 43 and two input terminals 45 are provided. One input terminal 45 is electrically connected to the upper electrode 41, inputting current or voltage. The other input terminal 45 is electrically connected to the lower electrode 42, connected to a reference potential. The input terminal 45 is, for example, exposed on the upper surface of the cladding 29.

[0076] The path wiring 44 connects the output terminal 46 to the upper electrode 41 or the lower electrode 42. The output terminal 46 is correspondingly arranged with the path wiring 44. Here, as an example, two path wirings 44 and two output terminals 46 are provided. One output terminal 46 is electrically connected to the upper electrode 41 and outputs an electrical signal. The other output terminal 46 is electrically connected to the lower electrode 42 and is connected to a reference potential. The output terminal 46 is, for example, exposed on the upper surface of the cladding 29.

[0077] The path wirings 43, 44, input terminal 45, and output terminal 46 contain a conductive material. The material of the path wirings 43, 44, input terminal 45, and output terminal 46 can be the same as that used for the upper electrode 41 and lower electrode 42 illustrated above.

[0078] Reference Figure 7 The operation of reflecting light LR onto the magnetic element 30 of the directional light device 1A is explained. Figure 7 It is a local magnification Figure 5 A diagram of the periphery of the magnetic element 30. Figure 7 This schematically illustrates the action of reflected light LR illuminating the magnetic element 30.

[0079] like Figure 7 As shown, the magnetic element 30 is disposed near the light exit port 27o. The magnetic element 30 is disposed in a manner that is embedded in the cladding 29 and is separated from the upper surface of the output waveguide 27.

[0080] Near-infrared light emitted from laser diode 14 is emitted outward as light LE from light emission port 27o. The emitted light LE is reflected by the human eye (the irradiated object E) and travels in the opposite direction along the same optical path as the emitted light LE, illuminating the light emission surface 10o where light emission port 27o is formed. Figure 7 In the process, the emitted light LE is emitted from the light emission port 27° in the positive x direction, and the reflected light LR is emitted towards the light emission surface 10° in the negative x direction.

[0081] The reflected light LR, which illuminates the light exit surface 10o, diffuses and propagates within the cladding 29. At least a portion of the reflected light LR reaches and illuminates the magnetic element 30 disposed within the cladding 29. At least a portion of the reflected light LR illuminates the magnetic element 30 from a direction intersecting the stacking direction of the magnetic element 30. Specifically, at least a portion of the reflected light LR illuminates the magnetic element 30 from a direction perpendicular to the stacking direction. The magnetic element 30 outputs an electrical signal corresponding to the intensity of the illuminated reflected light LR, thereby enabling the measurement of the intensity of the reflected light LR.

[0082] In the aforementioned prior art, the direction and position of the reflected light LR need to be properly adjusted along the optical axis to ensure that a sufficient amount of reflected light LR is incident on the light outlet 27o of the output waveguide 27. However, there is a problem that this optical axis adjustment is not easy to perform. Moreover, in the prior art, the reflected light LR needs to propagate in the waveguide 20 (output waveguide 27 and monitoring waveguide connected to the output waveguide 27). However, due to the propagation loss of the output waveguide 27 and the monitoring waveguide, there is also a problem that a sufficiently strong reflected light LR cannot be irradiated onto the magnetic element 30.

[0083] In contrast, in the optical device 1A of the first embodiment, it is sufficient to direct the reflected light LR towards the light emitting surface 10o located around the light emitting port 27o. The magnetic element 30 is positioned to receive the reflected light LR propagating outside the waveguide 20. The reflected light LR, which illuminates the light emitting surface 10o, propagates within the cladding 29 without passing through the output waveguide 27, and then illuminates the magnetic element 30. According to this structure, high-precision optical axis adjustment (waveguide coupling) is not required to direct the reflected light LR towards the light emitting port 27o, nor is a monitoring waveguide necessary. Furthermore, the reflected light LR reaches the magnetic element 30 located near the light emitting port 27o without propagating within the waveguide 20. Therefore, propagation loss in the waveguide 20 is avoided, and a sufficient amount of reflected light LR can illuminate the magnetic element 30.

[0084] Furthermore, "near the light exit port 27o" where the magnetic element 30 is positioned means that the distance between the magnetic element 30 and the light exit port 27o is less than a predetermined distance. The distance between the magnetic element 30 and the light exit port 27o can be set in a way that allows the magnetic element 30 to sufficiently measure the intensity of the reflected light LR.

[0085] For example, the distance between the magnetic element 30 and the light exit port 27o can be set to less than 10 wavelengths of near-infrared light. Specifically, the wavelength range of near-infrared light is 780 nm to 2500 nm. For example, the distance between the magnetic element 30 and the light exit port 27o can be set to less than 25 μm (less than 10 wavelengths of 2500 nm). Alternatively, for example, the distance between the magnetic element 30 and the light exit port 27o can be set such that at least 10% of the reflected light LR irradiating the light exit surface 10o is directed to the magnetic element 30. By setting it as described above, sufficient reflected light LR can irradiate the magnetic element 30. Furthermore, these specific values ​​are merely examples. The distance between the magnetic element 30 and the light exit port 27o can be further increased based on the near-infrared light transmittance of the cladding 29, the near-infrared light sensitivity of the magnetic element 30, etc.

[0086] Reference Figure 8 The structure of the magnetic element 30 will be described. Figure 8 This is a cross-sectional view showing the magnetic element 30 of the optical device 1A in the first embodiment. Figure 8 In the diagram, the magnetization M31, M32, and M34 of the first ferromagnetic layer 31, the second ferromagnetic layer 32, and the third ferromagnetic layer 34 in their initial states are indicated by arrows.

[0087] like Figure 8 As shown, the magnetic element 30 has at least a first ferromagnetic layer 31, a second ferromagnetic layer 32, and a spacer layer 33. Figure 8 In this structure, the second ferromagnetic layer 32, the spacer layer 33, and the first ferromagnetic layer 31 are stacked sequentially in the positive z-direction to form a laminate. The upper surface of the spacer layer 33 is in contact with the lower surface of the first ferromagnetic layer 31. The lower surface of the spacer layer 33 is in contact with the upper surface of the second ferromagnetic layer 32. In this specification, the stacking direction of the magnetic element 30 refers to the stacking direction of the second ferromagnetic layer 32, the spacer layer 33, and the first ferromagnetic layer 31. Figure 8 In the middle, the stacking direction of the magnetic element 30 is consistent with the z-direction.

[0088] The magnetic element 30 is, for example, an MTJ (Magnetic Tunnel Junction) element. The first ferromagnetic layer 31 and the second ferromagnetic layer 32 are made of ferromagnetic materials, and the spacer layer 33 is made of an insulating material. In the magnetic element 30, the resistance value when current flows along the stacking direction varies according to the relative changes in the magnetization M31 of the first ferromagnetic layer 31 and the magnetization M32 of the second ferromagnetic layer 32. Such an element is also called a magnetoresistive element.

[0089] The stack constituting the magnetic element 30 includes a third ferromagnetic layer 34, a magnetic coupling layer 35, a base layer 36, a vertical magnetization induction layer 37, a capping layer 38, and a sidewall insulating layer 39. Other layers may also be included as needed. The longest width of the magnetic element 30 when viewed from the stacking direction is, for example, 10 nm to 2000 nm.

[0090] The first ferromagnetic layer 31 is a light-detecting layer whose magnetization M31 changes when illuminated by external light. The first ferromagnetic layer 31 is also called a magnetization-free layer. A magnetization-free layer is a layer containing a magnetic material whose magnetization changes when energy is applied from the outside. External energy applied to the first ferromagnetic layer 31 can be, for example, light illuminating from the outside, current flowing along the stacking direction of the magnetic element 30, or an external magnetic field. The magnetization M31 of the first ferromagnetic layer 31 changes according to the intensity of the light illuminating the first ferromagnetic layer 31.

[0091] The first ferromagnetic layer 31 comprises a ferromagnetic material. The first ferromagnetic layer 31 may, for example, comprise at least one of magnetic elements such as Co, Fe, or Ni. The first ferromagnetic layer 31 may also comprise non-magnetic elements such as B, Mg, Hf, and Gd along with the aforementioned magnetic elements. The first ferromagnetic layer 31 may, for example, be an alloy comprising both magnetic and non-magnetic elements. The first ferromagnetic layer 31 may also consist of multiple layers. The first ferromagnetic layer 31 may, for example, be a CoFeB alloy, a laminate consisting of Fe layers sandwiching CoFeB alloy layers, or a laminate consisting of CoFe layers sandwiching CoFeB alloy layers.

[0092] The first ferromagnetic layer 31 can be an in-plane magnetized film with an easy magnetization axis in the in-plane direction, or a perpendicularly magnetized film with an easy magnetization axis in the direction perpendicular to the film surface. The in-plane direction is the direction parallel to the xy plane, and the direction perpendicular to the film surface is the z direction.

[0093] The thickness of the first ferromagnetic layer 31 is, for example, 1.0 nm to 5.0 nm, preferably 1.0 nm to 2.0 nm. When the first ferromagnetic layer 31 is a perpendicularly magnetized film, if the thickness of the first ferromagnetic layer 31 is thinner, the perpendicular magnetic anisotropy becomes stronger due to the interface effect between the layers above and below the first ferromagnetic layer 31. As a result, the perpendicular magnetic anisotropy of the first ferromagnetic layer 31 becomes stronger, and the force required for the magnetization M31 of the first ferromagnetic layer 31 to return to the direction perpendicular to the film surface (initial state) increases. On the other hand, if the thickness of the first ferromagnetic layer 31 is thicker, the interface effect between the layers above and below the first ferromagnetic layer 31 becomes relatively weaker. As a result, the perpendicular magnetic anisotropy of the first ferromagnetic layer 31 becomes weaker.

[0094] When the thickness of the first ferromagnetic layer 31 decreases, the volume of the ferromagnetic material decreases; conversely, when the thickness of the first ferromagnetic layer 31 increases, the volume of the ferromagnetic material increases. The reactivity of the magnetization M31 of the first ferromagnetic layer 31 when subjected to external energy is inversely proportional to the product of the magnetic anisotropy (Ku) and the volume (V) of the first ferromagnetic layer 31 (KuV). That is, when the product of the magnetic anisotropy and the volume of the first ferromagnetic layer 31 decreases, its reactivity to light increases. From this perspective, to improve the reactivity to light, it is preferable to reduce the volume of the first ferromagnetic layer 31 while appropriately designing its magnetic anisotropy.

[0095] When the thickness of the first ferromagnetic layer 31 is greater than 2.0 nm, an intercalation layer composed of Mo or W can be provided within the first ferromagnetic layer 31, for example. For example, a laminate consisting of a ferromagnetic layer, an intercalation layer, and a ferromagnetic layer stacked sequentially can be used as the first ferromagnetic layer 31. The overall perpendicular magnetic anisotropy of the first ferromagnetic layer 31 is improved due to the interfacial magnetic anisotropy at the interface between the intercalation layer and the ferromagnetic layer. The thickness of the intercalation layer is, for example, 0.1 nm to 0.6 nm.

[0096] The second ferromagnetic layer 32 is a magnetization-fixed layer. The magnetization-fixed layer is a layer composed of a magnetic material whose magnetization state is less likely to change compared to the magnetization-free layer when energy is applied from the outside.

[0097] When energy is applied from the outside, the direction and intensity of the magnetization M32 of the second ferromagnetic layer 32, which serves as a fixed magnetization layer, are less prone to change compared to the first ferromagnetic layer 31, which serves as a free magnetization layer. The coercivity of the second ferromagnetic layer 32 is, for example, greater than that of the first ferromagnetic layer 31. The second ferromagnetic layer 32, for example, has an easy magnetization axis in the same direction as the first ferromagnetic layer 31. The second ferromagnetic layer 32 can be an in-plane magnetization film or a perpendicular magnetization film.

[0098] The material constituting the second ferromagnetic layer 32 can be, for example, the same material as the first ferromagnetic layer 31. The second ferromagnetic layer 32 can also be, for example, a laminate consisting of Co with a thickness of 0.4 nm to 1.0 nm, Mo with a thickness of 0.1 nm to 0.5 nm, a CoFeB alloy with a thickness of 0.3 nm to 1.0 nm, and Fe with a thickness of 0.3 nm to 1.0 nm, stacked sequentially.

[0099] The magnetization M32 of the second ferromagnetic layer 32 can also be fixed, for example, by magnetic coupling between the second ferromagnetic layer 32 and the third ferromagnetic layer 34 via the magnetic coupling layer 35. In this case, the structure in which the second ferromagnetic layer 32, the magnetic coupling layer 35 and the third ferromagnetic layer 34 are combined is sometimes referred to as a magnetization fixing layer.

[0100] The third ferromagnetic layer 34 is magnetically coupled to the second ferromagnetic layer 32, for example. The magnetic coupling is, for example, antiferromagnetic coupling, generated through RKKY interactions. The material constituting the third ferromagnetic layer 34 can, for example, be the same material as the first ferromagnetic layer 31. The material of the magnetic coupling layer 35 can, for example, be Ru, Ir, etc.

[0101] Spacer layer 33 is a non-magnetic layer disposed between the first ferromagnetic layer 31 and the second ferromagnetic layer 32. Spacer layer 33 is sandwiched between the first ferromagnetic layer 31 and the second ferromagnetic layer 32. Spacer layer 33 is made of a layer using a conductor, an insulator, or a semiconductor, or a layer containing current-carrying points made of conductors in an insulator. The film thickness of spacer layer 33 can be adjusted according to the orientation directions of the magnetization M31 of the first ferromagnetic layer 31 and the magnetization M32 of the second ferromagnetic layer 32 in the initial state, as described later.

[0102] For example, when the spacer layer 33 is made of an insulator, the magnetic element 30 has a magnetic tunnel junction composed of a first ferromagnetic layer 31, a spacer layer 33, and a second ferromagnetic layer 32. Such an element is called an MTJ element. In this case, the magnetic element 30 can exhibit the TMR (Tunnel Magnetoresistance) effect. When the spacer layer 33 is made of a non-magnetic conductive material, the magnetic element 30 can exhibit the GMR (Giant Magnetoresistance) effect. Such an element is called a GMR element. The magnetic element 30 is called an MTJ element, a GMR element, etc., depending on the material of the spacer layer 33, and the names differ, but they are all collectively referred to as magnetoresistive effect elements.

[0103] When the spacer layer 33 is made of an insulating material, it can be made of materials including aluminum oxide, magnesium oxide, titanium oxide, or silicon oxide. The spacer layer 33 can also contain elements such as Al, B, Si, and Mg, and magnetic elements such as Co, Fe, and Ni in these insulating materials. By adjusting the thickness of the spacer layer 33 to exhibit a high TMR effect between the first ferromagnetic layer 31 and the second ferromagnetic layer 32, a high magnetoresistivity change rate can be obtained. To efficiently exhibit the TMR effect, the thickness of the spacer layer 33 can be set to approximately 0.5 nm to 5.0 nm, or further to approximately 1.0 nm to 2.5 nm.

[0104] When the spacer layer 33 is made of a non-magnetic conductive material, conductive materials such as Cu, Ag, Au, or Ru can be used. In order to efficiently exhibit the GMR effect, the film thickness of the spacer layer 33 can be set to about 0.5 nm to 5.0 nm, or further set to about 2.0 nm to 3.0 nm.

[0105] When the spacer layer 33 is made of a non-magnetic semiconductor material, the spacer layer 33 can be made of metal materials such as zinc oxide, indium oxide, tin oxide, germanium oxide, gallium oxide, or ITO. In this case, the film thickness of the spacer layer 33 can be set to about 1.0 nm to 4.0 nm.

[0106] When using a layer containing a current-carrying point formed by a conductor in a non-magnetic insulator as the spacer layer 33, it can also be configured such that the current-carrying point is formed by a non-magnetic conductor such as Cu, Au, or Al within a non-magnetic insulator made of alumina or magnesium oxide. Alternatively, the conductor can be made of magnetic elements such as Co, Fe, or Ni. In this case, the film thickness of the spacer layer 33 can be set to approximately 1.0 nm to 2.5 nm. The current-carrying point can be, for example, a columnar shape. The diameter of the columnar shape when viewed from a direction perpendicular to the film surface can be set to 1.0 nm to 5.0 nm.

[0107] A substrate layer 36 is disposed between the third ferromagnetic layer 34 and the lower electrode 42. The substrate layer 36 is a seed layer or a buffer layer. The seed layer is a layer that improves the crystallinity of the layers stacked on it. The seed layer may contain, for example, Pt, Ru, Hf, Zr, or NiFeCr. The thickness of the seed layer is, for example, 1.0 nm to 5.0 nm. The buffer layer is a layer that mitigates lattice mismatch between different crystals. The buffer layer may contain, for example, Ta, Ti, W, Zr, Hf, or nitrides of these elements. The thickness of the buffer layer is, for example, 1.0 nm to 5.0 nm.

[0108] A capping layer 38 is disposed between the first ferromagnetic layer 31 and the upper electrode 41. The capping layer 38 prevents damage to the underlying layer during the manufacturing process and improves the crystallinity of the underlying layer during annealing. To ensure sufficient light is irradiated onto the first ferromagnetic layer 31, the thickness of the capping layer 38 is, for example, 3.0 nm or less. The capping layer 38 is, for example, MgO, W, Mo, Ru, Ta, Cu, Cr, or a laminate thereof.

[0109] The vertical magnetization induced layer 37 is formed when the first ferromagnetic layer 31 is a vertically magnetized film. The vertical magnetization induced layer 37 is stacked on the first ferromagnetic layer 31. The vertical magnetization induced layer 37 induces vertical magnetic anisotropy in the first ferromagnetic layer 31. The vertical magnetization induced layer 37 is, for example, magnesium oxide, W, Ta, Mo, etc. When the vertical magnetization induced layer 37 is magnesium oxide, it is preferable to have oxygen vacancies in the magnesium oxide to improve conductivity. The film thickness of the vertical magnetization induced layer 37 is, for example, 0.5 nm to 2.0 nm.

[0110] The sidewall insulating layer 39 covers the periphery of the laminate including the first ferromagnetic layer 31 and the second ferromagnetic layer 32. The sidewall insulating layer 39 is, for example, an oxide, nitride, or oxynitride of Si, Al, or Mg.

[0111] The manufacturing method of the magnetic element 30 will be described below. The magnetic element 30 can be manufactured using a layering process, an annealing process, and a machining process.

[0112] In a portion of the substrate 28 on which the waveguide 20 is formed, a cladding layer 29 is stacked, and a lower electrode 42 is disposed thereon. Next, a base layer 36, a third ferromagnetic layer 34, a magnetic coupling layer 35, a second ferromagnetic layer 32, a spacer layer 33, a first ferromagnetic layer 31, a vertical magnetization induced layer 37, and a capping layer 38 are sequentially stacked on the lower electrode 42. Each layer is formed, for example, by sputtering.

[0113] Next, the films stacked as described above are annealed. The annealing temperature is, for example, 250°C to 450°C. Afterward, the stacked films are processed into predetermined columnar shapes using photolithography and etching. The columnar shapes can be cylindrical or prismatic. For example, the shortest width of the columnar shape when viewed from the stacking direction can be set to 10 nm to 2000 nm, or it can be set to 30 nm to 500 nm.

[0114] Next, an insulating layer is formed to cover the side of the columnar body. This insulating layer becomes the sidewall insulating layer 39. The sidewall insulating layer 39 can also be stacked multiple times. Then, the upper surface of the capping layer 38 is exposed from the sidewall insulating layer 39 using CMP (chemical mechanical polishing), and the upper electrode 41 is fabricated on the capping layer 38.

[0115] Using the above-described process, the magnetic element 30 can be manufactured. The magnetic element 30 does not require bonding to the substrate material using an adhesive layer or the like, and therefore can be manufactured in a manner independent of the substrate material. The magnetic element 30 can be fabricated using the same process as that used to form the waveguide 20 on the substrate 28. For example, the waveguide 20 and the magnetic element 30 can be formed on the same substrate 28 using a vacuum deposition process or the like. Furthermore, by further laminating the cladding layer 29 around the sidewall insulating layer 39, the magnetic element 30 is disposed within the cladding layer 29.

[0116] exist Figure 8 The diagram schematically illustrates, along with the magnetic element 30, an upper electrode 41 in contact with the upper surface of the magnetic element 30, a lower electrode 42 in contact with the lower surface of the magnetic element 30, and a circuit connected to the upper electrode 41 and the lower electrode 42.

[0117] The upper electrode 41 is connected, for example, to the input terminal Pin and the output terminal Pout, and the lower electrode 42 is connected, for example, to the reference potential terminal PG. The input terminal Pin corresponds to an input terminal 45 electrically connected to the upper electrode 41. The output terminal Pout corresponds to an output terminal 46 electrically connected to the upper electrode 41. The reference potential terminal PG corresponds to another input terminal 45 and another output terminal 46 electrically connected to the lower electrode 42. The reference potential terminal PG is connected to a reference potential. The reference potential can also be located outside the optical device 1A. The reference potential can be ground G or something other than ground G.

[0118] The magnetic element 30 converts the change in the state of the irradiated light into an electrical signal and outputs it. More specifically, the output voltage or output current of the electrical signal output from the magnetic element 30 varies according to the intensity of the irradiated light.

[0119] The input terminal (Pin) is connected to the power supply (PS). The power supply (PS) can be a current source or a voltage source. The power supply (PS) can be installed on the optical device 1A or located externally to the optical device 1A.

[0120] When the input terminal Pin is connected to the power supply PS, which acts as a current source, the output terminal Pout outputs the resistance value of the magnetic element 30 in the stacking direction as a voltage. When the input terminal Pin is connected to the power supply PS, which acts as a voltage source, the output terminal Pout outputs the resistance value of the magnetic element 30 in the stacking direction as a current. If it is not necessary to apply current or voltage to the magnetic element 30 from the outside, the input terminal Pin and the power supply PS may not be provided.

[0121] Reference Figure 9 and Figure 10 The mechanism by which the magnetic element 30 operates as a light sensor will be explained. Figure 9 This is a diagram illustrating the first mechanism of operation related to the magnetic element 30 of the optical device 1A in the first embodiment. Figure 10 This diagram illustrates the second mechanism of operation related to the magnetic element 30 of the optical device 1A in the first embodiment. Figure 9 and Figure 10 In the upper layer curve diagram, the vertical axis represents the intensity of light irradiating the first ferromagnetic layer 31, and the horizontal axis represents time. Figure 9 and Figure 10 The middle layer diagram illustrates the first ferromagnetic layer 31, the second ferromagnetic layer 32, and the spacer layer 33. Figure 10 In the lower layer of the graph, the vertical axis represents the resistance value in the stacking direction of the magnetic element 30, and the horizontal axis represents time.

[0122] It is known that the output voltage or output current of the electrical signal output from the magnetic element 30 varies according to the intensity of the irradiated light. The exact mechanism by which the output voltage or output current of the electrical signal output from the magnetic element 30 varies according to the intensity of the irradiated light is not yet fully understood, but the following two mechanisms can be considered, for example: The first mechanism is that the direction of magnetization varies according to the intensity of the light irradiating the magnetic element 30. The second mechanism is that the magnitude of magnetization varies according to the intensity of the light irradiating the magnetic element 30.

[0123] Reference Figure 9 The first mechanism of operation related to the magnetic element 30 of the optical device 1A in the first embodiment will be described.

[0124] When the first ferromagnetic layer 31 is irradiated with light of a first intensity (hereinafter referred to as the initial state), the magnetization M31 of the first ferromagnetic layer 31 and the magnetization M32 of the second ferromagnetic layer 32 are parallel. At this time, the resistance value in the stacking direction of the magnetic element 30 exhibits a first resistance value R1, and the magnitude of the output voltage or output current from the magnetic element 30 exhibits a first value. The first intensity can also be in the state where the first ferromagnetic layer 31 is not irradiated with light (i.e., the light intensity is zero).

[0125] For example, when a certain current (sensing current) flows along the stacking direction of the magnetic element 30, a voltage is generated across the two ends of the magnetic element 30 in the stacking direction. The resistance value of the magnetic element 30 in the stacking direction can be calculated using Ohm's law based on this voltage value. The output voltage from the magnetic element 30 is generated between the upper electrode 41 and the lower electrode 42.

[0126] exist Figure 9In the example shown, it is preferable to allow the sensing current to flow from the first ferromagnetic layer 31 toward the second ferromagnetic layer 32. By allowing the sensing current to flow from the first ferromagnetic layer 31 toward the second ferromagnetic layer 32, a spin-transfer torque in the same direction as the magnetization M32 of the second ferromagnetic layer 32 acts on the magnetization M31 of the first ferromagnetic layer 31. Thus, the magnetization M31 of the first ferromagnetic layer 31 and the magnetization M32 of the second ferromagnetic layer 32 are initially parallel to each other. Furthermore, by allowing the sensing current to flow from the first ferromagnetic layer 31 toward the second ferromagnetic layer 32, it is possible to prevent the magnetization M31 of the first ferromagnetic layer 31 from reversing during operation.

[0127] When the intensity of the light irradiating the magnetic element 30 changes, the external energy applied to the first ferromagnetic layer 31 changes. As a result, the direction of the magnetization M31 of the first ferromagnetic layer 31 tilts relative to the initial state. The angle between the magnetization M31 of the first ferromagnetic layer 31 in the initial state and the magnetization M31 of the first ferromagnetic layer 31 in the state after being irradiated with light is greater than 0° and less than 90°.

[0128] When the magnetization M31 of the first ferromagnetic layer 31 tilts relative to its initial state, the resistance value in the stacking direction of the magnetic element 30 changes, and the output voltage or output current from the magnetic element 30 changes. The greater the intensity of the light irradiated onto the magnetic element 30, the more significantly the direction of the magnetization M31 of the first ferromagnetic layer 31 tilts relative to its initial state. Figure 9 As shown, depending on the tilt of the magnetization M31 of the first ferromagnetic layer 31, the resistance value in the stacking direction of the magnetic element 30 changes to, for example, a second resistance value R2, a third resistance value R3, and a fourth resistance value R4. Consequently, the output voltage or output current from the magnetic element 30 changes to, for example, a second value, a third value, and a fourth value.

[0129] The greater the intensity of the light illuminating the magnetic element 30, the greater the resistance value in the order of resistance value R1, resistance value R2, resistance value R3, and resistance value R4. When the power supply PS is a constant current source, the output voltage from the magnetic element 30 increases in the order of value 1, value 2, value 3, and value 4. When the power supply PS is a constant voltage source, the output current from the magnetic element 30 decreases in the order of value 1, value 2, value 3, and value 4.

[0130] Since the spin-transfer torque in the same direction as the magnetization M32 of the second ferromagnetic layer 32 acts on the magnetization M31 of the first ferromagnetic layer 31, when the intensity of the light irradiated onto the first ferromagnetic layer 31 returns to the first intensity, the magnetization M31 of the first ferromagnetic layer 31 returns to its initial state. At this time, the resistance value in the stacking direction of the magnetic element 30 returns to the first resistance value R1, and the output voltage or output current from the magnetic element 30 returns to the first value.

[0131] Here, as an example, the case where magnetization M31 and magnetization M32 are parallel in the initial state is explained. However, magnetization M31 and magnetization M32 can also be antiparallel in the initial state (the magnetizations are oriented in opposite directions). In this case, the greater the tilt of magnetization M31 relative to the initial state, the smaller the resistance value in the stacking direction of the magnetic element 30. When the initial state is defined as the antiparallel state of magnetization M31 and magnetization M32, the sensing current preferably flows from the second ferromagnetic layer 32 toward the first ferromagnetic layer 31. By causing the sensing current to flow from the second ferromagnetic layer 32 toward the first ferromagnetic layer 31, a spin-transfer torque in the opposite direction to the magnetization M32 of the second ferromagnetic layer 32 acts on the magnetization M31 of the first ferromagnetic layer 31. Thus, magnetization M31 and magnetization M32 are antiparallel to each other in the initial state.

[0132] Reference Figure 10 A second mechanism relating to the operation of the magnetic element 30 of the optical device 1A in the first embodiment will be explained.

[0133] Figure 10 The initial state shown is the same as Figure 9 The initial states shown are the same. Figure 10 In the example shown, it is also preferable to allow a certain current (sensing current) to flow from the first ferromagnetic layer 31 toward the second ferromagnetic layer 32. By allowing the sensing current to flow from the first ferromagnetic layer 31 toward the second ferromagnetic layer 32, a spin-transfer torque in the same direction as the magnetization M32 of the second ferromagnetic layer 32 acts on the magnetization M31 of the first ferromagnetic layer 31, thus maintaining the initial state.

[0134] When the intensity of the light irradiating the magnetic element 30 changes, the energy applied from the outside to the first ferromagnetic layer 31 changes. As a result, the magnitude of the magnetization M31 of the first ferromagnetic layer 31 decreases relative to the initial state.

[0135] When the magnetization M31 of the first ferromagnetic layer 31 decreases relative to the initial state, the resistance value in the stacking direction of the magnetic element 30 changes, and the output voltage or output current from the magnetic element 30 changes. The greater the intensity of the light irradiated onto the magnetic element 30, the smaller the magnitude of the magnetization M31 of the first ferromagnetic layer 31 relative to the initial state. Figure 10As shown, depending on the magnitude of the magnetization M31 of the first ferromagnetic layer 31, the resistance value in the stacking direction of the magnetic element 30 changes to, for example, a second resistance value R2, a third resistance value R3, and a fourth resistance value R4. Consequently, the output voltage or output current from the magnetic element 30 changes to, for example, a second value, a third value, and a fourth value.

[0136] The greater the intensity of the light illuminating the magnetic element 30, the greater the resistance value in the order of resistance value R1, resistance value R2, resistance value R3, and resistance value R4. When the power supply PS is a constant current source, the output voltage from the magnetic element 30 increases in the order of value 1, value 2, value 3, and value 4. When the power supply PS is a constant voltage source, the output current from the magnetic element 30 decreases in the order of value 1, value 2, value 3, and value 4.

[0137] When the intensity of the light irradiating the first ferromagnetic layer 31 returns to the first intensity, the magnetization M31 of the first ferromagnetic layer 31 returns to its initial state. At this time, the resistance value in the stacking direction of the magnetic element 30 returns to the first resistance value R1, and the output voltage or output current from the magnetic element 30 returns to the first value.

[0138] exist Figure 10 Similarly, in the initial state, magnetization M31 and magnetization M32 can also be antiparallel. In this case, the smaller the size of magnetization M31 relative to the initial state, the smaller the resistance value in the stacking direction of the magnetic element 30. When the initial state is set as the antiparallel state of magnetization M31 and magnetization M32, the sensing current preferably flows from the second ferromagnetic layer 32 toward the first ferromagnetic layer 31.

[0139] exist Figure 9 The first mechanism shown and Figure 10 In any of the principles of the second mechanism shown, the electrical signal output from the magnetic element 30 varies according to the intensity of the light illuminating the magnetic element 30. The magnetic element 30 functions as a light sensor that detects changes in the state of the illuminating light and outputs an electrical signal corresponding to the intensity of the light.

[0140] [Second Embodiment]

[0141] The second embodiment of this disclosure will be described. Figure 11 This is a perspective view showing the vicinity of the magnetic element 30 of the optical device 1B in the second embodiment. Figure 12 It means Figure 11 A top view of the vicinity of the magnetic element 30. Figure 13 It means Figure 11 A cross-sectional view near the magnetic element 30. Figure 13 The cross-section shown is the cross-section of magnetic element 30 in the zx plane, and along... Figure 1 The cross-section of the BB line shown corresponds to this. In the second embodiment, the same reference numerals are used for the same constituent elements as in the first embodiment, and descriptions are omitted where appropriate.

[0142] like Figures 11-13 As shown, the optical device 1B in the second embodiment has a plurality of magnetic elements 30. The plurality of magnetic elements 30 are disposed near the light exit port 27o. The plurality of magnetic elements 30 are disposed, for example, embedded within the cladding 29 of the optical waveguide element 10B. The plurality of magnetic elements 30 are electrically connected to the upper electrode 41 and the lower electrode 42, and each magnetic element 30 functions as a photosensor for detecting reflected light LR.

[0143] According to the second embodiment, by configuring multiple magnetic elements 30, the illumination area of ​​the reflected light LR can be increased, thereby improving the signal-to-noise ratio (SN ratio) and enhancing detection accuracy. Furthermore, configuring multiple magnetic elements 30 ensures redundancy, guaranteeing the reliability and availability of the reflected light LR detection.

[0144] exist Figures 11-13 In the example shown, eight magnetic elements 30 are arranged in an array near the light exit port 27o. More specifically, four magnetic elements 30 are arranged in two columns, with adjacent columns of magnetic elements 30 arranged in an alternating staggered configuration. This effectively increases the area of ​​reflected light LR entering the cladding 29 from the light exit surface 10o and illuminating the multiple magnetic elements 30.

[0145] [Third Implementation]

[0146] The third embodiment of this disclosure will be described. Figure 14 This is a perspective view showing the vicinity of the magnetic element 30 of the optical device 1C in the third embodiment. Figure 15 It means Figure 14 A top view of the vicinity of the magnetic element 30. Figure 16 It means Figure 14 A cross-sectional view near the magnetic element 30. Figure 16 The cross-section shown is the cross-section of magnetic element 30 in the zx plane, and along... Figure 1 The cross-section of the BB line corresponds to this. In the third embodiment, the same reference numerals are used for the same constituent elements as in the first embodiment, and descriptions are omitted where appropriate.

[0147] The optical device 1C in the third embodiment has a magnetic element 30. The magnetic element 30 is disposed near the light exit port 27o. The magnetic element 30 is disposed, for example, embedded within the cladding 29 of the optical waveguide element 10C.

[0148] like Figures 14-16As shown, the magnetic element 30 is electrically connected to the upper electrode 41, the lower electrode 42, the path wiring 47, and the input / output terminal 48. The difference between the optical device 1C in the third embodiment and the optical device 1A in the first embodiment is that the input terminal 45 and the output terminal 46 are shared input / output terminals 48.

[0149] The path wiring 47 connects the input / output terminals 48 to the upper electrode 41 or the lower electrode 42. The input / output terminals 48 are correspondingly arranged with the path wiring 47. Here, as an example, two path wirings 47 and two input / output terminals 48 are provided. One input / output terminal 48 is electrically connected to the upper electrode 41, inputting current or voltage and outputting an electrical signal. The other input / output terminal 48 is electrically connected to the lower electrode 42 and connected to a reference potential. The input / output terminals 48 are, for example, exposed on the upper surface of the cladding 29.

[0150] According to the third embodiment, by utilizing a shared input / output terminal 48 for current or voltage input and electrical signal output, the number of terminals can be reduced. This allows for further miniaturization of the optical device 1C, creating space on the substrate 28 for arranging other components, thus increasing design flexibility.

[0151] [Fourth Implementation]

[0152] The fourth embodiment of this disclosure will be described. Figure 17 This is a perspective view showing the vicinity of the magnetic element 30 of the optical device 1D in the fourth embodiment. Figure 18 It means Figure 17 A cross-sectional view near the magnetic element 30. Figure 18 The cross-section shown is the cross-section of magnetic element 30 in the zx plane, and along... Figure 1 The cross-section of the BB line corresponds to this. In the fourth embodiment, the same reference numerals are used for the same constituent elements as in the first embodiment, and descriptions are omitted where appropriate.

[0153] like Figure 17 and Figure 18 As shown, the optical device 1D in the fourth embodiment differs from the optical device 1A in the first embodiment in that the stacking direction of the magnetic element 30 is tilted relative to the z-direction.

[0154] The optical device 1D in the fourth embodiment has a magnetic element 30. The magnetic element 30 is disposed near the light exit port 27o and is disposed in such a way that it is embedded in the cladding 29 of the optical waveguide element 10D.

[0155] The stacking direction of the magnetic element 30 can also be configured to be tilted relative to the z-direction. At least a portion of the reflected light LR illuminates the magnetic element 30 from a direction intersecting the stacking direction of the magnetic element 30. However, in the first embodiment described above, at least a portion of the reflected light LR illuminates the magnetic element 30 from a direction perpendicular to the stacking direction, while in the fourth embodiment, at least a portion of the reflected light LR illuminates the magnetic element 30 from a direction tilted relative to the stacking direction (a direction not perpendicular to the stacking direction). The angle between the stacking direction of the magnetic element 30 and the z-direction is not particularly limited, but can be set to, for example, 45°.

[0156] exist Figure 17 and Figure 18 In this configuration, the upper surface of the magnetic element 30 is arranged facing the direction of arrival of the reflected light LR, i.e., the light emitting surface 10o side. In this case, the material of the upper electrode 41 is preferably a material that is transparent to the wavelength range of the reflected light LR. Alternatively, the lower surface of the magnetic element 30 may be arranged facing the light emitting surface 10o side. In this case, the material of the lower electrode 42 is preferably a material that is transparent to the wavelength range of the reflected light LR.

[0157] According to the fourth embodiment, by tilting the magnetic element 30, the light-receiving area of ​​the magnetic element 30 receiving the reflected light LR can be increased. This increases the interaction between the magnetic element 30 and the reflected light LR, thereby improving the detection accuracy of the reflected light LR.

[0158] [Fifth Embodiment]

[0159] The fifth embodiment of this disclosure will be described. Figure 19 This is a perspective view showing the vicinity of the magnetic element 30 of the optical device 1E in the fifth embodiment. Figure 20 It means Figure 19 A cross-sectional view near the magnetic element 30. Figure 20 The cross-section shown is the cross-section of magnetic element 30 in the zx plane, and along... Figure 1 The cross-section of the BB line corresponds to this. In the fifth embodiment, the same reference numerals are used for the same constituent elements as in the first embodiment, and descriptions are omitted where appropriate.

[0160] like Figure 19 and Figure 20 As shown, the optical device 1E in the fifth embodiment differs from the optical device 1A in the first embodiment in that it includes a reflector 50.

[0161] The optical device 1E in the fifth embodiment has a magnetic element 30. The magnetic element 30 is disposed near the light exit port 27o. The magnetic element 30 is disposed, for example, embedded in the cladding 29 of the optical waveguide element 10E.

[0162] Reflector 50 is disposed near light exit port 27o, embedded within cladding 29. Reflected light LR, illuminating light exit surface 10o, diffuses and propagates within cladding 29. Reflector 50 reflects a portion of the reflected light LR, altering its direction of travel. A mirror, for example, can be used as reflector 50. The mirror has an inclined surface 51 for reflecting light. Figure 19 and Figure 20 In the example shown, reflector 50 changes (reflects) the direction of travel of reflected light LR, which propagates in the negative x-direction within cladding 29, to the positive z-direction. The normal of the inclined surface 51 forms an angle of 45° with both the x and z directions, for example.

[0163] The magnetic element 30 is positioned where light from the reflector 50 can reach. Figure 19 and Figure 20 In the example shown, the magnetic element 30 is positioned above the reflector 50. At least a portion of the reflected light LR has its direction of travel altered by the reflector 50, illuminating the magnetic element 30 from the stacking direction of the magnetic element 30.

[0164] exist Figure 19 and Figure 20 In this configuration, the lower surface of the magnetic element 30 is arranged facing the reflector 50. In this case, the material of the lower electrode 42 is preferably a material that is transparent to the wavelength range of the reflected light LR. Alternatively, the upper surface of the magnetic element 30 may be arranged facing the reflector 50. In this case, the material of the lower electrode 42 is preferably a material that is transparent to the wavelength range of the reflected light LR. Furthermore, the magnetic element 30 may be arranged such that its stacking direction is tilted relative to the z-direction, or its side surface may face the reflector 50.

[0165] According to the fifth embodiment, by using the reflector 50 to change the travel direction of the reflected light LR propagating within the cladding 29, the irradiation efficiency of the reflected light LR irradiating the magnetic element 30 can be improved. Furthermore, the placement position of the magnetic element 30 can be flexibly set, increasing the design freedom.

[0166] [Sixth Implementation]

[0167] The sixth embodiment of this disclosure will be described. Figure 21 This is a top view of the optical device 1F in the sixth embodiment. Figure 22 yes Figure 21 A top view of the light modulation unit 60. In the sixth embodiment, the same reference numerals are used to label the same components as in the first embodiment, and descriptions are omitted where appropriate.

[0168] like Figure 21 As shown, the optical waveguide element 10F of the optical device 1F includes an optical modulation unit 60 that modulates the intensity of visible light of each color emitted from laser diodes 11, 12, and 13. Laser diodes 11, 12, and 13 can be laser diodes that emit laser light of a certain intensity. The optical modulation unit 60 is provided, for example, in input waveguides 21, 22, and 23 respectively, and can independently modulate visible light of each color.

[0169] The optical modulation section 60 has a Mach-Zehnder type waveguide 70 with a Mach-Zehnder interferometer structure as waveguide 20. As the material of the Mach-Zehnder type waveguide 70, a material with electro-optic effect is preferably used, for example, a material containing lithium niobate as the main component is preferably used.

[0170] The following is about Figure 22 The optical modulation unit 60 shown will be described in detail. Furthermore, in Figure 22 The diagram shows a partial optical modulation section 60 provided in the input waveguide 21, but the optical modulation sections 60 provided in the input waveguides 22 and 23 also have the same structure. Figure 22 The optical modulation section 60 shown is an example and is not limited to this structure.

[0171] Figure 22 The optical modulation 60 shown includes an upstream waveguide 71, a wave splitter 72, a first waveguide 73, a second waveguide 74, a wave combiner 75, and a downstream waveguide 76. The upstream waveguide 71 forms the portion of the input waveguide 21 near the light entrance 21i. The downstream waveguide 76 forms the portion of the input waveguide 21 near the first wave combiner 25.

[0172] The upstream waveguide 71 branches into the first waveguide 73 and the second waveguide 74 at the wave-splitting section 72. The first waveguide 73 and the second waveguide 74 extend parallel to each other and merge at the wave-combining section 75 to form the downstream waveguide 76.

[0173] The optical modulation unit 60 also includes electrodes 81, 82, 83, and 84 for applying an electric field to the Mach-Zehnder waveguide 70, power supplies 85 and 86, and a terminating resistor 87. Power supply 85 applies a modulation voltage to the Mach-Zehnder waveguide 70 via electrodes 81 and 82. Power supply 86 applies a DC bias voltage to the Mach-Zehnder waveguide 70 via electrodes 83 and 84.

[0174] During optical modulation, a voltage is applied between electrodes 81 and 82. This applies an electric field to the first waveguide 73 and the second waveguide 74, causing their refractive indices to change due to an electro-optic effect. Visible light emitted from the laser diode 11 propagates in the upstream waveguide 71 and is split by the wave-splitting section 72, then propagates in the first waveguide 73 and the second waveguide 74. When a refractive index difference is generated between the first waveguide 73 and the second waveguide 74, a phase difference is generated between the light propagating in the first waveguide 73 and the light propagating in the second waveguide 74. By controlling this phase difference, the intensity of the light combined by the wave-combining section 75 can be controlled to a desired value.

[0175] According to the sixth embodiment, optical modulation can be performed using the optical modulation section 60 installed on the optical waveguide element 10F. Compared with the case of controlling the intensity of the emitted light from the laser diodes 11, 12, and 13, excellent responsiveness can be achieved while suppressing power consumption.

[0176] [Optical System]

[0177] The optical system of the present invention will be described. Figure 23 This is a conceptual diagram of the publicly disclosed optical system 100. Figure 23 The example shown is an optical system 100 having optical device 1A in the first embodiment, but optical devices 1B to 1F in the second to sixth embodiments may also be used.

[0178] This disclosure provides an optical system 100 incorporating the optical devices 1A to 1F described in embodiments 1 to 6 above. The optical system 100, for example, constitutes an image display device that displays information that can be visually recognized as an image (still image and moving image). The optical system 100, for example, can be installed in an eyeglass-type terminal such as an XR glasses 200.

[0179] Figure 23 The XR glasses 200 shown have a light source module 110, an optical system 120, a laser driver 130, a light scanning mirror driver 140, and a video controller 150 that controls these drivers.

[0180] The XR glasses 200 can be equipped with the optical devices 1A to 1F described in embodiments 1 to 6 above as a light source module 110. The light source module 110 is provided, for example, in the frame 201 of the XR glasses 200.

[0181] The optical system 120 performs optical processing on the emitted light LE from the light source module 110. For example, it includes a collimating lens 121, a slit 122, an ND filter 123, and a scanning mirror 124. Figure 23 The optical system 120 shown is one example, but other structures are also possible.

[0182] As the optical scanning mirror 124, a MEMS mirror can be used, for example. In order to project a two-dimensional image, a biaxial MEMS mirror that vibrates in a manner that reflects laser light by changing the angle in the horizontal and vertical directions is preferably used as the optical scanning mirror 124.

[0183] exist Figure 23 In the XR glasses 200 shown, the light source module 110 mounted on the frame 201 emits outgoing light LE. The outgoing light LE is reflected by the light scanning mirror 124 and further reflected by the lens 202 of the XR glasses 200. The light reflected by the lens 202 enters the human eye (eyeball) and forms an image on the retina M, thus enabling visual recognition as an image.

[0184] Figure 23 The XR glasses 200 shown have eye-tracking functionality. Eye tracking uses near-infrared light emitted from a laser diode 14. The near-infrared light emitted from the laser diode 14 is reflected by the human eyeball. Examples of reflective parts of the eyeball include the cornea, pupil, iris, retina, and sclera. The reflected light LR travels in the opposite direction to the emitted light LE along the same optical path as the emitted light LE before reaching the light source module 110.

[0185] The reflected light LR illuminates the light emitting surfaces 10o of the optical devices 1A to 1F constituting the light source module 110. A portion of the reflected light LR that illuminates the light emitting surfaces 10o propagates within the cladding 29 and illuminates the magnetic element 30. The magnetic element 30 outputs an electrical signal corresponding to the intensity of the reflected light LR. The XR glasses 200 can determine the movement of the gaze position (focus point) based on the near-infrared illumination position adjusted by the light scanning mirror 124 and the intensity of its reflected light LR.

[0186] [Derivative example]

[0187] Figure 24 This is a top view schematic diagram of the optical device 1G in a derivative example of this disclosure. The aforementioned optical devices 1A to 1F are configured to emit both visible light and near-infrared light, but optical device 1G is configured to emit only near-infrared light.

[0188] Figure 24 The optical device 1G shown includes a laser diode 14, an optical waveguide element 10G, and a magnetic element 30. A waveguide 90 for propagating light is formed in the optical waveguide element 10G. A light entrance port 90i is formed at one end of the waveguide 90. A light exit port 90o is formed at the other end of the waveguide 90. The waveguide 90 corresponds to the waveguide 20 described above. The light entrance port 90i and the light exit port 90o correspond to the light entrance port 24i and the light exit port 27o described above, respectively.

[0189] Laser diode 14 emits near-infrared light. The laser emitted by laser diode 14 is incident on the light inlet 90i of waveguide 90 and exits as the outgoing light LE from the light outlet 90o. The outgoing light LE illuminates the object E. The reflected light LR, after being reflected by the object E, travels in the opposite direction along the same optical path as the outgoing light LE and illuminates the light exiting surface 10o of the optical waveguide element 10G.

[0190] In the optical device 1G, the magnetic element 30 is also disposed near the light exit port 90°. The magnetic element 30 is disposed, for example, embedded within the cladding 29 of the optical waveguide element 10G.

[0191] exist Figure 24 In the optical device 1G shown, the magnetic element 30 and its surrounding structure are the same as those in the optical device 1A of the first embodiment described above. However, it may also be configured to have the same structure as in the second to fifth embodiments described above.

[0192] The reflected light LR, which is incident on the light exit surface 10o, propagates within the cladding 29 and irradiates the magnetic element 30. The magnetic element 30 outputs an electrical signal corresponding to the intensity of the irradiated reflected light LR, thereby enabling the measurement of the intensity of the reflected light LR.

[0193] Thus, according to a derivative of this disclosure, an optical device 1G for eye-tracking applications can be provided, which emits near-infrared light as emitted light LE and measures the intensity of its reflected light LR. Furthermore, according to a derivative of this disclosure, an optical system for eye-tracking applications incorporating the optical device 1G can also be provided.

[0194] Although embodiments of this disclosure have been described, this disclosure is not limited to these embodiments. Various modifications and alterations can be made, and the embodiments can be appropriately combined, without departing from the spirit of this disclosure.

[0195] As described above, this disclosure has the effect of not requiring high-precision optical axis adjustment and being able to properly illuminate the magnetic element with a simple structure, which is useful for optical detection technology as a whole. In particular, this disclosure has the effect of being able to properly illuminate the magnetic element with reflected light from the human eyeball, which is useful for eye-tracking technology as a whole.

[0196] This disclosure has been described with respect to a limited number of embodiments, but it should be understood that those skilled in the art will be able to conceive of various other embodiments that possess the advantages of this disclosure without departing from its spirit and scope. Therefore, the technical scope of the disclosed subject matter should be defined only by the claims.

Claims

1. An optical device, characterized in that, This optical device has the following features: At least one magnetic element having a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer; A laser diode that emits laser light; as well as waveguide, The waveguide has at least one light inlet for the laser light from the laser diode to enter and a light outlet for the laser light to exit to the outside. The at least one magnetic element is disposed near the light emission port.

2. The optical device according to claim 1, characterized in that, At least a portion of the reflected light from the laser emitted from the light outlet irradiates the at least one magnetic element.

3. The optical device according to claim 2, characterized in that, The at least one magnetic element is positioned to receive the reflected light propagating on the outside of the waveguide.

4. The optical device according to claim 1 or 2, characterized in that, The optical device also includes a substrate on which the waveguide is formed.

5. The optical device according to claim 4, characterized in that, The substrate is configured to contain aluminum oxide.

6. The optical device according to claim 4, characterized in that, The waveguide is formed as a lithium niobate layer disposed on the substrate.

7. The optical device according to claim 4, characterized in that, The optical device also has a cladding covering the waveguide. The at least one magnetic element is disposed within the cladding.

8. The optical device according to claim 1 or 2, characterized in that, The optical device also includes a reflector located near the light emission port.

9. The optical device according to claim 1 or 2, characterized in that, The laser diode emits near-infrared light as the laser.

10. An optical system, characterized in that, The optical system comprises: the optical device as described in claim 1 or 2; and an optical system that guides the laser emitted from the optical device to the irradiated object.

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