Optical Devices and Systems

Abstract

To provide a new optical device.SOLUTION: The optical device comprises: at least one magnetic element including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer interposed between the first ferromagnetic layer and the second ferromagnetic layer; a laser diode; and a waveguide. The waveguide includes: at least one input waveguide optically connected to the laser diode; and an output waveguide connected to the input waveguide. The magnetic element is irradiated with at least part of light propagating through at least one of the input waveguide and the output waveguide.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to optical devices and optical systems. [Background technology]

[0002] In recent years, augmented reality (AR) glasses and small projectors have been attracting attention, and small planar lightwave circuits (PLCs) using laser diodes are also attracting attention. Laser diodes are capable of rendering images with high energy efficiency.

[0003] For example, Patent Document 1 describes a light source with a monitoring function that can be used in a small projector. The light source with a monitoring function described in Patent Document 1 has a detection element using a semiconductor photodiode (PD). The semiconductor photodiode monitors the light output. The light source with a monitoring function described in Patent Document 1 adjusts the white balance based on the monitoring result of the light output. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-180513 A Summary of the Invention [Problem to be solved by the invention]

[0005] The semiconductor photodiodes, which are fabricated as separate components from the substrate on which the planar lightwave circuit is formed, are large in size. A new breakthrough is required for the further development of optical devices.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a novel optical device and optical system. [Means for solving the problem]

[0007] In order to solve the above problems, the following means are provided.

[0008] (1) An optical device according to a first aspect includes 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, and a waveguide, the waveguide having at least one input waveguide optically connected to the laser diode and an output waveguide connected to the input waveguide, and at least a portion of light propagating through at least one of the input waveguide and the output waveguide is irradiated to the magnetic element.

[0009] (2) In the optical device according to the above aspect, the waveguide may contain lithium niobate as a main component.

[0010] (3) The optical device according to the above aspect may further include a substrate, the waveguide being formed on the substrate, and the substrate may include aluminum oxide.

[0011] (4) The optical device according to the above aspect may further include a substrate, the waveguide being formed on the substrate, and the magnetic element being on or above the substrate.

[0012] (5) The optical device according to the above aspect may further include a reflector, and the reflector may reflect at least a portion of the light toward the magnetic element.

[0013] (6) In the optical device according to the above aspect, at least a portion of the light may be irradiated onto the magnetic element in a direction intersecting a stacking direction of the magnetic element.

[0014] (7) In the optical device according to the above aspect, at least a part of the light may be irradiated onto the magnetic element from a stacking direction of the magnetic element.

[0015] (8) The optical device according to the above aspect may further include a support member that is a separate member from the substrate on which the waveguide is formed and supports the magnetic element.

[0016] (9) In the optical device according to the above aspect, the waveguide may further include a monitoring waveguide, the monitoring waveguide may be connected to at least one of the input waveguide and the output waveguide, and at least a portion of the light may propagate through the monitoring waveguide.

[0017] (10) In the optical device according to the above aspect, the at least one input waveguide may be a plurality of input waveguides, the at least one magnetic element may be a plurality of magnetic elements, and the optical device may further include a plurality of monitoring waveguides connected to the respective input waveguides, and each of the magnetic elements may be irradiated with light propagating through each of the plurality of monitoring waveguides.

[0018] (11) In the optical device according to the above aspect, the at least one magnetic element may be a plurality of magnetic elements, and a first magnetic element of the plurality of magnetic elements may be irradiated with at least a portion of light propagating through at least one of the input waveguide and the output waveguide in a direction from the laser diode toward the input waveguide or the output waveguide, and a second magnetic element of the plurality of magnetic elements may be irradiated with at least a portion of light output from the output waveguide and reflected by an irradiated body.

[0019] (12) An optical system according to a second aspect includes an optical device according to the above aspect, and an optical system that guides light output from the optical device to an object to be illuminated. Effect of the Invention

[0020] The optical device and optical system according to the above aspects can monitor light based on a novel principle. [Brief description of the drawings]

[0021] [Figure 1]FIG. 1 is a plan view of an optical device according to a first embodiment. [Diagram 2] 2 is a cross-sectional view of a waveguide of the optical device according to the first embodiment. FIG. [Diagram 3] 1 is a perspective view of the vicinity of a magnetic element of an optical device according to a first embodiment. [Figure 4] 2 is a cross-sectional view of the magnetic element and its vicinity in the optical device according to the first embodiment. FIG. [Diagram 5] 3 is an example of a monitoring circuit of the optical device according to the first embodiment. [Figure 6] 4 is another example of a monitoring circuit for the optical device according to the first embodiment. [Figure 7] 2 is a cross-sectional view of the magnetic element according to the first embodiment and its vicinity. FIG. [Figure 8] 5A to 5C are diagrams for explaining a first mechanism of the magnetic element according to the first embodiment. [Figure 9] 5A to 5C are diagrams for explaining a second mechanism of the magnetic element according to the first embodiment. [Figure 10] 4 is a cross-sectional view of the vicinity of a magnetic element in another example of the optical device according to the first embodiment. FIG. [Figure 11] FIG. 11 is a perspective view of the vicinity of a magnetic element of an optical device according to a second embodiment. [Figure 12] FIG. 11 is a cross-sectional view of the vicinity of a magnetic element of an optical device according to a second embodiment. [Figure 13] 13 is another cross-sectional view of the magnetic element and its vicinity in the optical device according to the second embodiment. FIG. [Figure 14] FIG. 11 is a plan view of an optical device according to a third embodiment. [Figure 15] FIG. 11 is a cross-sectional view of the vicinity of a magnetic element of an optical device according to a third embodiment. [Figure 16] FIG. 11 is a cross-sectional view of the vicinity of a magnetic element of an optical device according to a fourth embodiment. [Figure 17] FIG. 13 is a cross-sectional view of the vicinity of a magnetic element of an optical device according to a fifth embodiment. [Figure 18] FIG. 13 is a perspective view of the vicinity of a magnetic element of an optical device according to a fifth embodiment. [Figure 19]FIG. 13 is a plan view of an optical device according to a sixth embodiment. [Figure 20] FIG. 13 is a plan view of an optical device according to a seventh embodiment. [Figure 21] FIG. 13 is a plan view of an optical device according to an eighth embodiment. [Figure 22] 13 is a perspective view of a first example of the vicinity of a magnetic element of an optical device according to an eighth embodiment. FIG. [Diagram 23] FIG. 23 is a perspective view of a second example of the vicinity of the magnetic element of the optical device according to the eighth embodiment. [Figure 24] FIG. 13 is a cross-sectional view of the vicinity of a magnetic element of an optical device according to a ninth embodiment. [Diagram 25] FIG. 23 is a plan view of the optical device according to the tenth embodiment. [Figure 26] FIG. 1 is a conceptual diagram of an optical system using an optical device. [Figure 27] FIG. 23 is a plan view of an optical device according to a modified example of the tenth embodiment. [Figure 28] FIG. 2 is a plan view of the light modulation element. [Figure 29] FIG. 1 is a plan view of an example of an optical device that can be used in a dedicated eye-tracking system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, the embodiments will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the characteristics easier to understand, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and may be appropriately modified and implemented within the scope of the effects of the present invention.

[0023] The directions are defined as follows. One direction in the plane in which the substrate 27 (see FIG. 2) extends is the x-direction, and the direction in the plane perpendicular to the x-direction is the y-direction. The direction perpendicular to the substrate 27 (perpendicular to the x-direction and y-directions) is the z-direction. Hereinafter, the +z direction may be expressed as "up" and the -z direction as "down". Up and down do not necessarily coincide with the directions in which gravity is applied.

[0024] "First embodiment" 1 is a plan view of an optical device 100 according to a first embodiment. The optical device 100 has a plurality of laser diodes 11, 12, and 13, a waveguide 20, and a magnetic element 30.

[0025] Each of the multiple laser diodes 11, 12, and 13 outputs a laser beam. For example, the laser diode 11 is a red laser that outputs light in a wavelength range of 590 nm or more and 800 nm or less. For example, the laser diode 12 is a green laser that outputs light in a wavelength range of 490 nm or more and less than 590 nm. For example, the laser diode 13 is a green laser that outputs light in a wavelength range of 380 nm or more and less than 490 nm. The following description will be given based on an example in which three lasers of red, green, and blue are used as an example, but the number of laser diodes, the wavelength ranges to be output, etc. are not limited to this case.

[0026] The waveguide 20 includes, for example, input waveguides 21, 22, and 23, a multiplexing waveguide 24, an output waveguide 25, and a monitoring waveguide 26.

[0027] Each of the input waveguides 21, 22, and 23 is optically connected to each of the laser diodes 11, 12, and 13. For example, the light output from the laser diode 11 propagates through the input waveguide 21. For example, the light output from the laser diode 12 propagates through the input waveguide 22. For example, the light output from the laser diode 13 propagates through the input waveguide 23.

[0028] The multiplexing path 24 is located between the input waveguides 21, 22, 23 and the output waveguide 25. The light propagating through each of the input waveguides 21, 22, 23 is combined at the multiplexing path 24. The output waveguide 25 is connected to the multiplexing path 24. The output waveguide 25 is connected to the input waveguides 21, 22, 23 via the multiplexing path 24, and the light from the input waveguides 21, 22, 23 propagates to the output waveguide 25.

[0029] The monitoring waveguide 26 is connected to at least one of the input waveguides 21, 22, 23 and the output waveguide 25. At least a part of the light propagating through at least one of the input waveguides 21, 22, 23 and the output waveguide 25 propagates through the monitoring waveguide 26. Hereinafter, at least a part of the light propagating through at least one of the input waveguides 21, 22, 23 and the output waveguide 25 may be referred to as monitoring light. The monitoring waveguide 26 shown in FIG. 1 is connected to the output waveguide 25. The monitoring light branches off from the output waveguide 25 and propagates through the monitoring waveguide 26.

[0030] Fig. 2 is a cross-sectional view of the waveguide 20 of the optical device according to the first embodiment. Fig. 2 is a cross-section taken along the line AA in Fig. 1. Fig. 2 is a cross-section of input waveguides 21, 22, and 23 of the waveguide 20.

[0031] The input waveguides 21, 22, and 23 are on a substrate 27. The substrate 27 includes, for example, aluminum oxide. The substrate 27 is, for example, sapphire. Each of the input waveguides 21, 22, and 23 protrudes from the substrate 27 in the z direction. Each of the input waveguides 21, 22, and 23 includes, for example, lithium niobate as a main component. Some elements of the lithium niobate may be replaced with other elements. Each of the input waveguides 21, 22, and 23 is covered with, for example, a clad 28. The clad 28 is, for example, SiO2, Al2O3, MgF2, La2O3, ZnO, HfO2, MgO, Y2O3, CaF2, In2O3, or a mixture thereof. The materials of the input waveguides 21, 22, and 23 and the clad 28 are not limited to this example. For example, the cores constituting the input waveguides 21, 22, and 23 may be silicon or silicon oxide doped with germanium oxide, and the clad may be silicon oxide.

[0032] Fig. 3 is a perspective view of the vicinity of the magnetic element 30 of the optical device 100 according to the first embodiment. Fig. 4 is a cross-sectional view of the vicinity of the magnetic element 30 of the optical device 100 according to the first embodiment.

[0033] The magnetic element 30 is located at a position where the monitoring light is irradiated. The magnetic element 30 is, for example, at the end of the output end of the monitoring waveguide 26. The monitoring light is, for example, irradiated to the magnetic element 30 from a direction intersecting the lamination direction of the magnetic element 30. The monitoring light is, for example, irradiated to the side surface of the magnetic element 30. The magnetic element 30 is formed on the same substrate as the substrate 27 on which the waveguide 20 is formed. In other words, the magnetic element 30 and the waveguide 20 are incorporated in one product and cannot be separated. The magnetic element 30 is on the substrate 27 or above the substrate 27.

[0034] The magnetic element 30 is electrically connected to, for example, electrodes 41 and 42, via wirings 43 and 44, an input terminal 45, and an output terminal 46.

[0035] The electrode 41 is connected to a first surface of the magnetic element 30. The electrode 42 is connected to a second surface of the magnetic element 30. The first surface and the second surface face each other in the stacking direction of the magnetic element 30.

[0036] The electrodes 41 and 42 include a material having electrical conductivity. The electrodes 41 and 42 are made of a metal such as Cu, Al, Au, or Ru. Ta or Ti may be laminated above and below these metals. The electrodes 41 and 42 may also be a laminated film of Cu and Ta, a laminated film of Ta, Cu, and Ti, or a laminated film of Ta, Cu, and TaN. The electrodes 41 and 42 may also be made of TiN or TaN.

[0037] The electrodes 41 and 42 may be transparent to the wavelength region of light irradiated to the magnetic element 30. For example, the electrodes 41 and 42 may be transparent electrodes including transparent electrode materials such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium gallium zinc oxide (IGZO), etc. The electrodes 41 and 42 may also be configured to include a plurality of metal pillars in these transparent electrode materials.

[0038] The via wiring 43 connects the input terminal 45 and the electrode 41 or the electrode 42. There are, for example, two input terminals 45. A current or a voltage is input to one of the input terminals 45, and the other of the input terminals 45 is connected to a reference potential. The input terminal 45 is exposed, for example, on the upper surface of the clad 28. The via wiring 44 connects the output terminal 46 and the electrode 41 or the electrode 42. There are, for example, two output terminals 46. A signal is output from one of the output terminals 46, and the other of the output terminal 46 is connected to a reference potential. The output terminal 46 is exposed, for example, on the upper surface of the clad 28. The via wirings 43, 44, the input terminal 45, and the output terminal 46 include a material having electrical conductivity. The materials of the via wirings 43, 44, the input terminal 45, and the output terminal 46 can be the same as those given as examples of the electrodes 41 and 42.

[0039] 5 and 6 are examples of a light monitoring circuit using the magnetic element 30 of the optical device 100 according to the first embodiment. In FIG. 5 and FIG. 6, the electrode 41 is, for example, an input terminal P in and output terminal P out 5 and 6, the electrode 42 is connected to, for example, a reference potential terminal P G It is connected to the input terminal P in corresponds to one of the input terminals 45 in FIG. 3 and FIG. 4. out corresponds to one of the output terminals 46 in FIG. 3 and FIG. 4. G corresponds to the other of the input terminals 45 and the other of the output terminals 46 in Figures 3 and 4. The reference potential in Figures 5 and 6 is the ground G. The ground G may be provided outside the optical device 100. The reference potential may be something other than the ground G.

[0040] The magnetic element 30 converts the change in the state of the irradiated light (monitoring light L) into an electrical signal. The output voltage or output current from the magnetic element 30 changes depending on the intensity of the irradiated light (monitoring light L).

[0041] Input terminal P in is connected to a current source PS1 or a voltage source PS2. The current source PS1 and the voltage source PS2 may be external to the optical device 100. in When connected to the current source PS1, the output terminal P out The input terminal P outputs the resistance value of the magnetic element 30 in the lamination direction as a voltage. in When connected to voltage source PS2, output terminal P out When there is no need to apply a current or voltage to the magnetic element 30 from the outside, the input terminal P in And the current source PS1 or the voltage source PS2 may be omitted.

[0042] Fig. 7 is a cross-sectional view of the magnetic element 30 according to the first embodiment. In Fig. 7, electrodes 41 and 42 are shown at the same time, and the direction of magnetization of the ferromagnetic material in the initial state is indicated by an arrow.

[0043] The magnetic element 30 has at least a first ferromagnetic layer 31, a second ferromagnetic layer 32, and a spacer layer 33. The spacer layer 33 is located between the first ferromagnetic layer 31 and the second ferromagnetic layer 32. The magnetic element 30 may have a third ferromagnetic layer 34, a magnetic coupling layer 35, an underlayer 36, a perpendicular magnetization induction layer 37, a cap layer 38, a sidewall insulating layer 39, and the like in addition to the above. The magnetic element 30 has a maximum width of, for example, 2000 nm or less in a planar view from the stacking direction. The magnetic element 30 has a maximum width of, for example, 10 nm or more in a planar view from the stacking direction.

[0044] The magnetic element 30 is, for example, a magnetic tunnel junction (MTJ) element in which the spacer layer 33 is made of an insulating material. In this case, the magnetic element 30 changes a resistance value in the stacking direction (resistance value when a current flows in the stacking direction) according to a relative change between the state of magnetization M31 of the first ferromagnetic layer 31 and the state of magnetization M32 of the second ferromagnetic layer 32. Such an element is also called a magnetoresistance effect element.

[0045] The first ferromagnetic layer 31 is a light detection layer whose magnetization state changes when irradiated with light from the outside. The first ferromagnetic layer 31 is also called a magnetization free layer. The magnetization free layer is a layer including a magnetic material whose magnetization state changes when a predetermined external energy is applied. The predetermined external energy is, for example, light (monitoring light L) irradiated from the outside, a current flowing in the stacking direction of the magnetic element 30, or an external magnetic field. The state of the magnetization M31 of the first ferromagnetic layer 31 changes depending on the intensity of the light (monitoring light L) irradiated to the first ferromagnetic layer 31.

[0046] The first ferromagnetic layer 31 includes a ferromagnetic material. The first ferromagnetic layer 31 includes at least one of magnetic elements such as Co, Fe, or Ni. The first ferromagnetic layer 31 may include a nonmagnetic element such as B, Mg, Hf, or Gd in addition to the magnetic elements described above. The first ferromagnetic layer 31 may be, for example, an alloy including a magnetic element and a nonmagnetic element. The first ferromagnetic layer 31 may be composed of a plurality of layers. The first ferromagnetic layer 31 is, for example, a CoFeB alloy, a stacked body in which a CoFeB alloy layer is sandwiched between Fe layers, or a stacked body in which a CoFeB alloy layer is sandwiched between CoFe layers.

[0047] The first ferromagnetic layer 31 may be an in-plane magnetization film having an axis of easy magnetization in the in-plane direction, or a perpendicular magnetization film having an axis of easy magnetization in the direction perpendicular to the film plane (the lamination direction of the magnetic element 30).

[0048] The thickness of the first ferromagnetic layer 31 is, for example, 1 nm or more and 5 nm or less. The thickness of the first ferromagnetic layer 31 is preferably, for example, 1 nm or more and 2 nm or less. When the first ferromagnetic layer 31 is a perpendicular magnetization film, if the thickness of the first ferromagnetic layer 31 is thin, the perpendicular magnetic anisotropy application effect from the layers above and below the first ferromagnetic layer 31 is strengthened, and the perpendicular magnetic anisotropy of the first ferromagnetic layer 31 is enhanced. In other words, if the perpendicular magnetic anisotropy of the first ferromagnetic layer 31 is high, the force of the magnetization M31 returning to the direction perpendicular to the film surface (to the original state) is strengthened. On the other hand, if the thickness of the first ferromagnetic layer 31 is thick, the perpendicular magnetic anisotropy application effect from the layers above and below the first ferromagnetic layer 31 is relatively weak, and the perpendicular magnetic anisotropy of the first ferromagnetic layer 31 is weakened.

[0049] When the thickness of the first ferromagnetic layer 31 is decreased, the volume of the ferromagnetic body is decreased, and when the thickness is increased, the volume of the ferromagnetic body is increased. The responsiveness of the magnetization M31 of the first ferromagnetic layer 31 when external energy is applied is inversely proportional to the product (KuV) of the magnetic anisotropy (Ku) and the volume (V) of the first ferromagnetic layer 31. In other words, when the product of the magnetic anisotropy and the volume of the first ferromagnetic layer 31 is decreased, the responsiveness to light is increased. From this viewpoint, in order to increase the responsiveness to light, it is preferable to appropriately design the magnetic anisotropy of the first ferromagnetic layer 31 and then reduce the volume of the first ferromagnetic layer 31.

[0050] When the thickness of the first ferromagnetic layer 31 is greater than 2 nm, an insertion layer made of, for example, Mo or W may be provided in the first ferromagnetic layer 31. That is, the first ferromagnetic layer 31 may be a laminate in which a ferromagnetic layer, an insertion layer, and a ferromagnetic layer are laminated in this order. The interfacial magnetic anisotropy at the interface between the insertion layer and the ferromagnetic layer enhances the perpendicular magnetic anisotropy of the entire first ferromagnetic layer 31. The thickness of the insertion layer is, for example, 0.1 nm to 0.6 nm.

[0051] The second ferromagnetic layer 32 is a magnetization fixed layer. The magnetization fixed layer is a layer made of a magnetic material in which the state of magnetization is less likely to change than the magnetization free layer when a predetermined external energy is applied. For example, the magnetization direction of the magnetization fixed layer is less likely to change than the magnetization free layer when a predetermined external energy is applied. Also, for example, the magnitude of magnetization of the magnetization fixed layer is less likely to change than the magnetization free layer when a predetermined external energy is applied. The coercive force of the second ferromagnetic layer 32 is, for example, larger than the coercive force of the first ferromagnetic layer 31. The second ferromagnetic layer 32 has an easy magnetization axis in the same direction as the first ferromagnetic layer 31, for example. The second ferromagnetic layer 32 may be an in-plane magnetization film or a perpendicular magnetization film.

[0052] The material constituting the second ferromagnetic layer 32 is, for example, the same as that of the first ferromagnetic layer 31. The second ferromagnetic layer 32 may be, for example, a laminate in which Co is 0.4 nm to 1.0 nm thick, Mo is 0.1 nm to 0.5 nm thick, a CoFeB alloy is 0.3 nm to 1.0 nm thick, and Fe is 0.3 nm to 1.0 nm thick, laminated in this order.

[0053] The magnetization M32 of the second ferromagnetic layer 32 may be fixed, for example, by magnetic coupling with the third ferromagnetic layer 34 via the magnetic coupling layer 35. In this case, the combination of the second ferromagnetic layer 32, the magnetic coupling layer 35, and the third ferromagnetic layer 34 may be referred to as a magnetization fixed layer.

[0054] The third ferromagnetic layer 34 is magnetically coupled to, for example, the second ferromagnetic layer 32. The magnetic coupling is, for example, an antiferromagnetic coupling caused by RKKY interaction. The material constituting the third ferromagnetic layer 34 is, for example, the same as that of the first ferromagnetic layer 31. The magnetic coupling layer 35 is, for example, Ru, Ir, or the like.

[0055] The spacer layer 33 is a non-magnetic layer disposed between the first ferromagnetic layer 31 and the second ferromagnetic layer 32. The spacer layer 33 is composed of a layer made of a conductor, an insulator, or a semiconductor, or a layer including a current-carrying point made of a conductor in an insulator. The thickness of the 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 described later.

[0056] For example, when the spacer layer 33 is made of an insulator, the magnetic element 30 has a magnetic tunnel junction (MTJ) consisting of the first ferromagnetic layer 31, the spacer layer 33, and the second ferromagnetic layer 32. Such an element is called an MTJ element. In this case, the magnetic element 30 can exhibit a tunnel magnetoresistance (TMR) effect. When the spacer layer 33 is made of a metal, the magnetic element 30 can exhibit a giant magnetoresistance (GMR) effect. Such an element is called a GMR element. The magnetic element 30 may be called an MTJ element, a GMR element, or the like, depending on the material of the spacer layer 3, but is also collectively called a magnetoresistance effect element.

[0057] When the spacer layer 33 is made of an insulating material, a material containing aluminum oxide, magnesium oxide, titanium oxide, silicon oxide, or the like can be used for the spacer layer 33. The spacer layer 33 may contain elements such as Al, B, Si, Mg, or magnetic elements such as Co, Fe, Ni, in addition to these insulating materials. By adjusting the thickness of the spacer layer 33 so that a high TMR effect is generated between the first ferromagnetic layer 31 and the second ferromagnetic layer 32, a high magnetoresistance change rate can be obtained. In order to efficiently utilize the TMR effect, the thickness of the spacer layer 33 may be about 0.5 to 5.0 nm, or about 1.0 to 2.5 nm.

[0058] When the spacer layer 33 is made of a nonmagnetic conductive material, a conductive material such as Cu, Ag, Au, Ru, etc. can be used. In order to efficiently utilize the GMR effect, the thickness of the spacer layer 33 may be about 0.5 to 5.0 nm, or about 2.0 to 3.0 nm.

[0059] When the spacer layer 33 is made of a nonmagnetic semiconductor material, it can be made of a material such as zinc oxide, indium oxide, tin oxide, germanium oxide, gallium oxide, ITO, etc. In this case, the thickness of the spacer layer 33 may be about 1.0 to 4.0 nm.

[0060] When a layer including current-carrying points formed by a conductor in a nonmagnetic insulator is used as the spacer layer 33, the nonmagnetic insulator may be made of aluminum oxide or magnesium oxide and may include current-carrying points formed by a nonmagnetic conductor such as Cu, Au, or Al. The conductor may also be made of a magnetic element such as Co, Fe, or Ni. In this case, the thickness of the spacer layer 33 may be about 1.0 to 2.5 nm. The current-carrying points are, for example, columnar bodies with a diameter of 1 nm or more and 5 nm or less when viewed from a direction perpendicular to the film surface.

[0061] The underlayer 36 is between the second ferromagnetic layer 32 and the electrode 42. The underlayer 36 is a seed layer or a buffer layer. The seed layer enhances the crystallinity of the layer stacked on the seed layer. The seed layer is, for example, Pt, Ru, Hf, Zr, or NiFeCr. The seed layer has a thickness of, for example, 1 nm or more and 5 nm or less. The buffer layer is a layer that relieves lattice mismatch between different crystals. The buffer layer is, for example, Ta, Ti, W, Zr, Hf, or a nitride of these elements. The buffer layer has a thickness of, for example, 1 nm or more and 5 nm or less.

[0062] The cap layer 38 is between the first ferromagnetic layer 31 and the electrode 41. The cap layer 38 prevents damage to the lower layer during the process and improves the crystallinity of the lower layer during annealing. The thickness of the cap layer 38 is, for example, 3 nm or less so that the first ferromagnetic layer 31 is irradiated with sufficient light. The cap layer 38 is, for example, MgO, W, Mo, Ru, Ta, Cu, Cr, or a laminated film of these materials.

[0063] The perpendicular magnetization induced layer 37 is formed when the first ferromagnetic layer 31 is a perpendicular magnetization film. The perpendicular magnetization induced layer 37 is laminated on the first ferromagnetic layer 31. The perpendicular magnetization induced layer 37 induces perpendicular magnetic anisotropy in the first ferromagnetic layer 31. The perpendicular magnetization induced layer 37 is made of, for example, magnesium oxide, W, Ta, Mo, or the like. When the perpendicular magnetization induced layer 37 is made of magnesium oxide, it is preferable that the magnesium oxide has oxygen deficiency in order to increase the conductivity. The film thickness of the perpendicular magnetization induced layer 37 is, for example, 0.5 nm or more and 2.0 nm or less.

[0064] The sidewall insulating layer 39 covers the periphery of a stack 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.

[0065] The magnetic element 30 is fabricated by a lamination process for each layer, an annealing process, and a processing process. First, an electrode 42, an underlayer 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 perpendicular magnetization induction layer 37, and a cap layer 38 are laminated in this order on a substrate 27 (on a part of the cladding 28). The substrate 27 is the same as the substrate on which the waveguide 20 is formed. Each layer is formed by, for example, sputtering.

[0066] Next, the laminated film is annealed. The annealing temperature is, for example, 250° C. to 450° C. Then, the laminated film is processed into a predetermined columnar body by photolithography and etching. The columnar body may be a cylindrical body or a rectangular column. For example, the shortest width of the columnar body when viewed from the lamination direction may be 10 nm or more and 2000 nm or less, or 30 nm or more and 500 nm or less.

[0067] Next, an insulating layer is formed so as to cover the side surface of the columnar body. The insulating layer becomes a sidewall insulating layer 39. The sidewall insulating layer 39 may be laminated multiple times. Next, the upper surface of the cap layer 38 is exposed from the sidewall insulating layer 39 by chemical mechanical polishing (CMP), and an electrode 41 is formed on the cap layer 38. The above process results in the magnetic element 30. The magnetic element 30 can be manufactured regardless of the material constituting the base. Therefore, the magnetic element 30 can be manufactured directly on the substrate 27 on which the waveguide 20 is formed, without an adhesive layer or the like. The magnetic element 30 can be formed together with the waveguide 20 by a process on the same substrate 27. For example, the waveguide 20 and the magnetic element 30 can be formed on the same substrate 27 by a vacuum film formation process.

[0068] Next, a description will be given of some examples of the operation of the optical device 100. The operations performed by the optical device 100 include an output operation for multiplexing and outputting the light emitted from each of the laser diodes 11, 12, and 13, and a monitoring operation for monitoring the light emitted from each of the laser diodes 11, 12, and 13.

[0069] First, the output operation will be described. Light is emitted from each of laser diodes 11, 12, and 13. The light emitted from each of laser diodes 11, 12, and 13 is input to input waveguides 21, 22, and 23, respectively. The light output from laser diode 11 propagates through input waveguide 21. The light output from laser diode 12 propagates through input waveguide 22. The light output from laser diode 13 propagates through input waveguide 23.

[0070] The light propagating through the input waveguides 21, 22, and 23 are combined in a multiplexer 24. The light combined in the multiplexer 24 propagates through an output waveguide 25. The light combined in the multiplexer 24 is output from one end of the output waveguide 25.

[0071] Next, the monitoring operation will be described. In the monitoring operation, light is emitted from one of the laser diodes 11, 12, and 13. For example, light is emitted from the laser diode 11. In this case, the light emitted from the laser diode 11 propagates through the input waveguide 21, the multiplexing path 24, and the output waveguide 25 in this order. At least a part of the light propagating through the output waveguide 25 branches into the monitoring waveguide 26. The branched light propagates through the monitoring waveguide 26 as monitoring light.

[0072] The light (monitoring light) propagating through the monitoring waveguide 26 is irradiated onto the magnetic element 30. For example, the monitoring light is irradiated onto the magnetic element 30 from a direction intersecting the stacking direction of the magnetic element 30 (z direction in FIG. 3). For example, the monitoring light is irradiated onto a side surface of the magnetic element 30 from the y direction.

[0073] The output voltage or output current from the magnetic element 30 changes depending on the intensity of light (monitoring light L) irradiated to the first ferromagnetic layer 31. The exact mechanism by which the output voltage or output current from the magnetic element 30 changes due to light irradiation has not yet been clarified, but for example, the following two mechanisms are considered.

[0074] Fig. 8 is a diagram for explaining a first mechanism of operation of the magnetic element 30 according to the first embodiment. In the upper graph of Fig. 8, the vertical axis represents the intensity of light irradiated to the first ferromagnetic layer 31, and the horizontal axis represents time. In the lower graph of Fig. 8, the vertical axis represents the resistance value in the stacking direction of the magnetic element 30, and the horizontal axis represents time.

[0075] First, in a state where the first ferromagnetic layer 31 is irradiated with light of a first intensity (hereinafter referred to as an initial state), the magnetization M31 of the first ferromagnetic layer 31 and the magnetization M32 of the second ferromagnetic layer 32 are parallel to each other, the resistance value in the stacking direction of the magnetic element 30 indicates a first resistance value R1, and the magnitude of the output voltage or output current from the magnetic element 30 indicates a first value. The first intensity may be the case where the intensity of the light irradiated to the first ferromagnetic layer 31 is zero.

[0076] For example, when a sense current is applied to the magnetic element 30 in the stacking direction, a voltage is generated at both ends of the magnetic element 30 in the stacking direction, and the resistance value in the stacking direction of the magnetic element 30 can be calculated from the voltage value using Ohm's law. An output voltage from the magnetic element 30 is generated between the electrodes 41 and 42. In the example shown in FIG. 8, it is preferable to apply a sense current from the first ferromagnetic layer 31 to the second ferromagnetic layer 32. By applying a sense current in this direction, 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, and the magnetization M31 and the magnetization M32 become parallel in the initial state. In addition, by applying a sense current in this direction, it is possible to prevent the magnetization M31 of the first ferromagnetic layer 31 from being reversed during operation.

[0077] Next, the intensity of the light irradiated to the first ferromagnetic layer 31 changes. The magnetization M31 of the first ferromagnetic layer 31 is tilted from the initial state by external energy due to the light irradiation. The angle between the direction of the magnetization M31 of the first ferromagnetic layer 31 in a state where the first ferromagnetic layer 31 is not irradiated with light and the direction of the magnetization M31 in a state where the first ferromagnetic layer 31 is irradiated with light is both greater than 0° and smaller than 90°.

[0078] When the magnetization M31 of the first ferromagnetic layer 31 tilts from the initial state, the resistance value in the stacking direction of the magnetoresistance effect element 30 changes. Then, the output voltage or output current from the magnetic element 30 changes. For example, the greater the intensity of the light (monitoring light L) irradiated to the magnetic element 30, the greater the tilt of the magnetization M31 from the initial state. For example, the resistance value in the stacking direction of the magnetic element 30 changes to a second resistance value R2, a third resistance value R3, and a fourth resistance value R4 according to the tilt of the magnetization M31 of the first ferromagnetic layer 31, and the output voltage or output current from the magnetic element 30 changes to a second value, a third value, and a fourth value. The resistance values ​​increase in the order of the first resistance value R1, the second resistance value R2, the third resistance value R3, and the fourth resistance value R4. The output voltage from the magnetic element 30 increases in the order of the first value, the second value, the third value, and the fourth value. When the magnetic element 30 is connected to a constant voltage source, the output current from the magnetic element 30 decreases in the order of the first value, the second value, the third value, and the fourth value.

[0079] When the intensity of the light (monitoring light L) irradiated to the magnetic element 30 changes, the output voltage or output current (resistance value in the stacking direction of the magnetic element 30) from the magnetic element 30 changes. Therefore, the magnetic element 30 can detect the intensity of the monitoring light L as the output voltage or output current from the magnetic element 30 (resistance value of the magnetic element 30).

[0080] Since a spin transfer torque acts on the magnetization M31 of the first ferromagnetic layer 31 in the same direction as the magnetization M32 of the second ferromagnetic layer 32, when the intensity of the light irradiated to the first ferromagnetic layer 31 returns to the first intensity, the magnetization M31 tilted from the initial state returns to the initial state. When the magnetization M31 returns to the initial state, 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.

[0081] Here, the case where the magnetization M31 and the magnetization M32 are parallel in the initial state has been described as an example, but the magnetization M31 and the magnetization M32 may be antiparallel in the initial state. In this case, the resistance value in the stacking direction of the magnetic element 30 decreases as the magnetization M31 tilts (as the angle change from the initial state of the magnetization M31 increases). When the initial state is one in which the magnetization M31 and the magnetization M32 are antiparallel, it is preferable to flow the sense current from the second ferromagnetic layer 32 toward the first ferromagnetic layer 31. By flowing the sense current in this direction, 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, and the magnetization M31 and the magnetization M32 become antiparallel in the initial state.

[0082] Fig. 9 is a diagram for explaining a second mechanism of operation of the magnetic element 30 according to the first embodiment. In the upper graph of Fig. 9, the vertical axis represents the intensity of light irradiated to the first ferromagnetic layer 31, and the horizontal axis represents time. In the lower graph of Fig. 9, the vertical axis represents the resistance value in the stacking direction of the magnetic element 30, and the horizontal axis represents time.

[0083] The initial state shown in Fig. 9 is similar to the initial state shown in Fig. 8. In the example shown in Fig. 9, it is also preferable to flow the sense current from the first ferromagnetic layer 31 to the second ferromagnetic layer 32. By flowing the sense current in this direction, a spin transfer torque acts on the magnetization M31 of the first ferromagnetic layer 31 in the same direction as the magnetization M32 of the second ferromagnetic layer 32, and the initial state is maintained.

[0084] Next, the intensity of the light (monitoring light) irradiated to the first ferromagnetic layer 31 changes. The magnitude of the magnetization M31 of the first ferromagnetic layer 31 decreases from the initial state due to external energy caused by the irradiation of light. When the magnetization M31 of the first ferromagnetic layer 31 decreases from the initial state, the resistance value in the stacking direction of the magnetoresistance effect element 30 changes. Then, the output voltage or output current from the magnetic element 30 changes. For example, the greater the intensity of the light (monitoring light L) irradiated to the magnetic element 30, the smaller the magnitude of the magnetization M31. For example, 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 a second resistance value R2, a third resistance value R3, and a fourth resistance value R4, and the output voltage or output current from the magnetic element 30 changes to a second value, a third value, and a fourth value. The resistance values ​​increase in the order of the first resistance value R1, the second resistance value R2, the third resistance value R3, and the fourth resistance value R4. The output voltage from the magnetic element 30 increases in the order of the first value, the second value, the third value, and the fourth value. When the magnetic element 30 is connected to a constant voltage source, the output current from the magnetic element 30 decreases in the order of the first value, the second value, the third value, and the fourth value.

[0085] When the intensity of the light irradiated to the first ferromagnetic layer 31 returns to the first intensity, the magnitude of the magnetization M31 of the first ferromagnetic layer 31 returns to the original value, and the magnetic element 30 returns to the initial state. That is, 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.

[0086] 9, the magnetizations M31 and M32 may be anti-parallel in the initial state. In this case, the resistance value in the stacking direction of the magnetic element 30 decreases as the magnitude of the magnetization M31 decreases. When the magnetizations M31 and M32 are anti-parallel in the initial state, it is preferable to flow the sense current from the second ferromagnetic layer 32 to the first ferromagnetic layer 31.

[0087] Through the above-mentioned procedure, the intensity of the light output from laser diode 11 can be read as an output voltage or output current (resistance value in the stacking direction of magnetic element 30) from magnetic element 30. Then, using a similar procedure, the intensity of the light output from laser diode 12 and the intensity of the light output from laser diode 13 are measured in sequence.

[0088] The light output from one end of the output waveguide 25 is a combination of the light output from each of the laser diodes 11, 12, and 13. The white balance of the output light from the optical device 100 can be adjusted by adjusting the intensity of the light output from each of the laser diodes 11, 12, and 13. The intensity of the light output from each of the laser diodes 11, 12, and 13 can be adjusted, for example, by feeding back the measurement result of the output from the magnetic element 30 to each of the laser diodes 11, 12, and 13.

[0089] Furthermore, the smaller the volume of the first ferromagnetic layer 31, the more easily the magnetization M31 of the first ferromagnetic layer 31 changes in response to light irradiation. In other words, the smaller the volume of the first ferromagnetic layer 31, the more easily the magnetization M31 of the first ferromagnetic layer 31 is tilted or reduced by light irradiation. In other words, by reducing the volume of the first ferromagnetic layer 31, the magnetization M31 can be changed even with a small amount of light. That is, the magnetic element 30 according to the first embodiment can detect light with high sensitivity.

[0090] More precisely, the changeability of the magnetization M31 is determined by the magnitude of the product (KuV) of the magnetic anisotropy (Ku) and the volume (V) of the first ferromagnetic layer 31. The smaller the KuV, the smaller the amount of light that the magnetization M31 changes, and the larger the KuV, the larger the amount of light required to change the magnetization M31. In other words, the KuV of the first ferromagnetic layer 31 is designed according to the amount of light irradiated from the outside used in the application. When it is assumed to detect an extremely small amount of light, the KuV of the first ferromagnetic layer 31 can be reduced to enable the detection of such a small amount of light. This is a great advantage because the detection of such a small amount of light becomes difficult when the element size is reduced in conventional pn junction semiconductors. The KuV can be reduced by reducing the volume of the first ferromagnetic layer 31.

[0091] As described above, the optical device 100 according to the first embodiment can read the intensity of light output from each of the laser diodes 11, 12, and 13 from the output voltage or output current (resistance value in the stacking direction of the magnetic element 30) of the magnetic element 30. The optical device 100 according to the first embodiment can adjust the white balance of the light output from the output waveguide 25 by adjusting the intensity of the light output from each of the laser diodes 11, 12, and 13.

[0092] Although the first embodiment has been described in detail above with reference to the drawings, the first embodiment is not limited to this example.

[0093] 10, the stacking direction of the magnetic element 30 may be inclined with respect to the z direction. In this case, the monitoring light is irradiated onto the side surface of the magnetic element 30 and the first surface of the magnetic element 30 on the electrode 41 side.

[0094] "Second embodiment" Fig. 11 is a perspective view of the vicinity of the magnetic element 30 of the optical device 101 according to the second embodiment. Fig. 12 is a cross-sectional view of the vicinity of the magnetic element 30 of the optical device 101 according to the second embodiment. Fig. 13 is another cross-sectional view of the vicinity of the magnetic element 30 of the optical device 101 according to the second embodiment. In the second embodiment, configurations similar to those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0095] The optical device 101 has a reflector 50. The reflector 50 reflects the light (monitoring light) output from the monitoring waveguide 26 toward the magnetic element 30. The reflector 50 is located in the traveling direction of the monitoring light from the output end of the monitoring waveguide 26. The reflector 50 has an inclined surface that is inclined with respect to the traveling direction of the monitoring light.

[0096] The reflector 50 reflects light. The reflector 50 is, for example, a reflecting mirror.

[0097] The magnetic element 30 is formed in an insulating layer 29 formed on the cladding 28. The insulating layer 29 is, for example, made of the same material as the sidewall insulating layer 39. The magnetic element 30 is located above the substrate 27. The magnetic element 30 is located at a different height from the waveguide 20 and is located farther from the substrate 27 than the waveguide 20. The magnetic element 30 is located above a reflector 50, for example.

[0098] The light (monitoring light) reflected by the reflector 50 is irradiated to the magnetic element 30, for example, from the stacking direction of the magnetic element 30. In this case, the electrode 42 is transparent to the wavelength region of the light irradiated to the magnetic element 30. The electrode 42 transmits a part of the monitoring light, so that the monitoring light is irradiated to the magnetic element 30. Here, an example in which the electrode 42 is disposed closer to the reflector 50 than the electrode 41 is illustrated, but the electrode 41 may be disposed closer to the reflector 50 than the electrode 42 (the first ferromagnetic layer 31 may be disposed closer to the reflector 50 than the second ferromagnetic layer 32). In this case, the electrode 41 is transparent to the wavelength region of the light irradiated to the magnetic element 30. When the electrode 41 is disposed closer to the reflector 50 than the electrode 42, the efficiency of irradiating the monitoring light to the first ferromagnetic layer 31 is increased.

[0099] The optical device 101 according to the second embodiment has the same effects as the optical device 100. In addition, the reflector 50 allows the direction of irradiation of the monitoring light to the magnetic element 30 to be freely designed. For example, when the monitoring light is irradiated to the magnetic element 30 from the stacking direction, the light receiving area of ​​the magnetic element 30 can be secured to be wide.

[0100] "Third embodiment" Fig. 14 is a plan view of the optical device 102 according to the third embodiment as viewed from the z direction. Fig. 15 is a cross-sectional view of the vicinity of the magnetic element 30 of the optical device 102 according to the third embodiment. Fig. 15 is a cross-section taken along line CC in Fig. 14. In the third embodiment, configurations similar to those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0101] The optical device 102 has a support 60 that supports the magnetic element 30. The support 60 is a member separate from the substrate 27 on which the waveguide 20 is formed. The support 60 and the substrate 27 are fixed, for example, on a common support. The support 60 is, for example, made of the same material as the substrate 27. In the optical device 102, the magnetic element 30 is on or above the support 60. The magnetic element 30 is in an insulating layer 61 formed on the support 60. The insulating layer 61 is, for example, made of the same material as the sidewall insulating layer 39.

[0102] In the example shown in FIGS. 14 and 15, the height position of the magnetic element 30 in the z direction is aligned with the height position of the output end of the monitoring waveguide 26 in the z direction.

[0103] The optical device 102 according to the third embodiment has the same effects as the optical device 100. Furthermore, the magnetic element 30 and the waveguide 20 can be fabricated separately, which reduces restrictions during manufacturing.

[0104] "Fourth embodiment" 16 is a cross-sectional view of the vicinity of the magnetic element 30 of the optical device 103 according to the fourth embodiment. In the fourth embodiment, the same configurations as those in the third embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0105] Substrate 27A differs from substrate 27 in that a step is formed on the upper surface. Top surface S1 and top surface S2 are at different height positions in the z direction. Top surface S1 is the upper surface of substrate 27 at a position overlapping with waveguide 20 when viewed from the z direction. Waveguide 20 is formed on top surface S1. Top surface S2 is the upper surface of substrate 27 at a position overlapping with magnetic element 30 when viewed from the z direction.

[0106] The support 60 is placed on the upper surface S2. The magnetic element 30 is formed above the substrate 27 and on the support 60.

[0107] The optical device 103 according to the fourth embodiment has the same effects as the optical device 102 .

[0108] "Fifth embodiment" Fig. 17 is a cross-sectional view of the vicinity of the magnetic element 30 of the optical device 104 according to the fifth embodiment. Fig. 18 is a perspective view of the vicinity of the magnetic element 30 of the optical device 104 according to the fifth embodiment. In the fifth embodiment, the same configurations as in the fourth embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0109] In the optical device 104, the traveling direction of the monitoring light from the output end of the monitoring waveguide 26 coincides with the stacking direction of the magnetic element 30. The support 60 is installed, for example, so that the side surface of the support 60 when stacking the magnetic element 30 faces the upper surface S2 of the substrate 27A. The monitoring light is irradiated to the magnetic element 30, for example, from the stacking direction of the magnetic element 30. In this case, the electrode 41 is transparent to the wavelength range of the light irradiated to the magnetic element 30. The electrode 41 transmits a part of the monitoring light, so that the magnetic element 30 is irradiated with the monitoring light.

[0110] 18, the electrode 41 is connected to an input terminal 45A and an output terminal 46A. The electrode 42 is connected to the input terminal 45A through a via wiring 43 and to the output terminal 46A through a via wiring 44. The input terminal 45A and the output terminal 46A are formed on the side surface of the support 60.

[0111] The optical device 104 according to the fifth embodiment has the same effects as the optical device 103. Moreover, by irradiating the magnetic element 30 with monitoring light from the stacking direction, the light receiving area of ​​the magnetic element 30 can be secured to be wide.

[0112] Sixth embodiment 19 is a plan view of an optical device 105 according to the sixth embodiment, seen from the z direction. In the sixth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0113] The shape of the waveguide 20A of the optical device 105 is different from that of the waveguide 20 of the optical device 100. The waveguide 20A has, for example, input waveguides 21, 22, and 23, a multiplexing waveguide 24, an output waveguide 25, and a plurality of monitoring waveguides 26A, 26B, and 26C.

[0114] The monitoring waveguide 26A is connected to the input waveguide 21. The monitoring waveguide 26B is connected to the input waveguide 22. The monitoring waveguide 26C is connected to the input waveguide 23. At least a part of the light propagating through the input waveguide 21 propagates as monitoring light through the monitoring waveguide 26A. At least a part of the light propagating through the input waveguide 22 propagates as monitoring light through the monitoring waveguide 26B. At least a part of the light propagating through the input waveguide 23 propagates as monitoring light through the monitoring waveguide 26C.

[0115] The optical device 105 has a plurality of magnetic elements 30. Each magnetic element 30 is irradiated with light (monitoring light) propagating through each of the monitoring waveguides 26A, 26B, and 26C.

[0116] The optical device 105 according to the sixth embodiment has the same effects as the optical device 100 .

[0117] In the monitoring operation of the optical device 100 according to the first embodiment, the light output from the laser diodes 11, 12, and 13 is measured sequentially. In contrast, in the monitoring operation of the optical device 105 according to the sixth embodiment, the light output from the laser diodes 11, 12, and 13 can be simultaneously measured by each of the multiple magnetic elements 30.

[0118] Seventh embodiment 20 is a plan view of an optical device 106 according to the seventh embodiment, seen from the z direction. In the seventh embodiment, the same components as those in the sixth embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0119] The shape of the waveguide 20B of the optical device 106 is different from that of the waveguide 20A of the optical device 105. The waveguide 20B has, for example, a plurality of input waveguides 21, 22, and 23, a plurality of output waveguides 25A, 25B, and 25C, and a plurality of monitoring waveguides 26A, 26B, and 26C. The waveguide 20B does not have a multiplexing path 24. The output waveguide 25A is connected to the input waveguide 21. The output waveguide 25B is connected to the input waveguide 22. The output waveguide 25C is connected to the input waveguide 23.

[0120] In the output operation of optical device 106, the light propagating through input waveguides 21, 22, and 23 does not combine at multiplexer 24. If the output ends of output waveguides 25A, 25B, and 25C are sufficiently close to each other, the light output from each of output waveguides 25A, 25B, and 25C appears to the human eye as being combined.

[0121] The optical device 106 according to the seventh embodiment has the same effects as the optical device 105. Here, an example has been shown in which a plurality of monitoring waveguides 26A, 26B, and 26C are connected to the input waveguides 21, 22, and 23, but the monitoring waveguide 26A may be connected to the output waveguide 25A, the monitoring waveguide 26B may be connected to the output waveguide 25B, and the monitoring waveguide 26C may be connected to the output waveguide 25C.

[0122] Eighth embodiment 21 is a plan view of an optical device 107 according to the eighth embodiment, seen from the z direction. In the eighth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0123] The shape of the waveguide 20C of the optical device 107 is different from that of the waveguide 20 of the optical device 100. The optical device 107 does not have a monitoring waveguide 26. In the optical device 107, a part of the light output from the output end of the output waveguide 25 is irradiated onto the magnetic element 30 as monitoring light.

[0124] Fig. 22 is a perspective view of a first example of the vicinity of the magnetic element 30 of the optical device 107 according to the eighth embodiment. In Fig. 22, the output waveguide 25 has two separate output ends 25t1 and 25t2. The output end 25t1 is located at a different position in the x direction from the output end 25t2.

[0125] The light from the output end 25t1 travels toward the reflector 50. The light reflected by the reflector 50 is irradiated to the magnetic element 30 as monitoring light. That is, a part of the light output from the output end of the output waveguide 25 is irradiated to the magnetic element 30 as monitoring light. The output end 25t2 is exposed to the outside. The output light L out will be output.

[0126] Fig. 23 is a perspective view of a second example of the vicinity of the magnetic element 30 of the optical device 107 according to the eighth embodiment. In Fig. 23, the output waveguide 25 has two separate output ends 25t3 and 25t4. The output end 25t3 is located at a different position in the z direction from the output end 25t4.

[0127] The light from the output end 25t3 travels toward the reflector 50. The light reflected by the reflector 50 is irradiated to the magnetic element 30 as monitoring light. That is, a part of the light output from the output end of the output waveguide 25 is irradiated to the magnetic element 30 as monitoring light. The output end 25t4 is exposed to the outside. The output light L out will be output.

[0128] The optical device 107 according to the eighth embodiment has the same effects as the optical device 100.

[0129] "Ninth embodiment" 24 is a cross-sectional view of the vicinity of the magnetic element 30 of an optical device 108 according to the ninth embodiment. In the ninth embodiment, the same configurations as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0130] The magnetic element 30 is electrically connected to, for example, the electrodes 41 and 42, the via wiring 48, and the input / output terminal 47. In the optical device 108 according to the ninth embodiment, the input terminal and the output terminal for the magnetic element 30 are common.

[0131] The via wiring 48 connects the input / output terminal 47 to the electrode 41 or the electrode 42. There are, for example, two input / output terminals 47. A current or a voltage is input to one of the input / output terminals 47, and a signal is output from one of the input / output terminals 47. The other of the input / output terminals 47 is connected to a reference potential.

[0132] The optical device 108 according to the ninth embodiment has the same effects as the optical device 100 .

[0133] Tenth embodiment 25 is a plan view of an optical device 109 according to the tenth embodiment, as viewed in the z direction. In the tenth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0134] The optical device 109 includes a plurality of laser diodes 11, 12, 13, and 14, a waveguide 20D, and a plurality of magnetic elements 30.

[0135] The laser diode 14 outputs laser light. For example, the laser diode 14 is a near-infrared laser that outputs light (near-infrared light) in a wavelength range of 780 nm or more and 2500 nm or less.

[0136] The shape of the waveguide 20D of the optical device 109 is different from that of the waveguide 20 of the optical device 100. The optical device 109 has input waveguides 21, 22, 23, and 21A, a multiplexing path 24A, an output waveguide 25, and a plurality of monitoring waveguides 26D and 26E.

[0137] The input waveguide 21A is optically connected to the laser diode 14. For example, light output from the laser diode 14 propagates through the input waveguide 21A. The multiplexing path 24A is between the input waveguides 21, 22, 23, 21A and the output waveguide 25. The light propagating through each of the input waveguides 21, 22, 23, 21A is combined at the multiplexing path 24A. The output waveguide 25 is connected to the multiplexing path 24A. The output waveguide 25 is connected to the input waveguides 21, 22, 23, 21A via the multiplexing path 24A, and the light from the input waveguides 21, 22, 23, 21A propagates through the output waveguide 25.

[0138] Each of the multiple monitoring waveguides 26D, 26E is connected to the output waveguide 25. There may be multiple monitoring waveguides 26D, and each monitoring waveguide 26D may be individually connected to each of the input waveguides 21, 22, 23, 21A, as in the sixth embodiment. At least a part of the light propagating through at least one of the input waveguides 21, 22, 23, 21A and the output waveguide 25 propagates through the monitoring waveguide 26D. At least a part of the light propagating through the output waveguide 25 propagates through the monitoring waveguide 26E.

[0139] At the connection portion between first monitoring waveguide 26D and output waveguide 25, the angle that first monitoring waveguide 26D makes with the +x direction is, for example, smaller than 90°. At the connection portion between second monitoring waveguide 26E and output waveguide 25, the angle that second monitoring waveguide 26E makes with the +x direction is, for example, larger than 90°. The +x direction is, for example, the direction in output waveguide 25 in which the light output from laser diodes 11, 12, 13, and 14 proceeds toward the output end of output waveguide 25.

[0140] Monitoring light propagates through each of first monitoring waveguide 26D and second monitoring waveguide 26E. At least a portion of the light output from laser diodes 11, 12, 13, 14 and propagating through at least one of input waveguides 21, 22, 23, 21A and output waveguide 25 in a direction from laser diodes 11, 12, 13, 14 to input waveguides 21, 22, 23, 21A or output waveguide 25 propagates through first monitoring waveguide 26D. At least a portion of the light output from output waveguide 25 to the outside and reflected by the irradiated object propagates through second monitoring waveguide 26E. Hereinafter, of the monitoring light, at least a portion of the light output from laser diodes 11, 12, 13, 14 and propagating in a direction from laser diodes 11, 12, 13, 14 to input waveguide 21, 22, 23, 21A or output waveguide 25 will be referred to as the first monitoring light, and at least a portion of the light output from output waveguide 25 to the outside and reflected by the irradiated body will be referred to as the second monitoring light.

[0141] Each of the multiple magnetic elements 30 is the magnetic element 30 described above. One of the magnetic elements 30 is referred to as a first magnetic element 30A, and the other is referred to as a second magnetic element 30B. The first magnetic element 30A is located at a position where the first monitoring light is irradiated. The first magnetic element 30A is located at the end of the output end of the first monitoring waveguide 26D. The second magnetic element 30B is located at a position where the second monitoring light is irradiated. The second magnetic element 30B is located at the end of the output end of the second monitoring waveguide 26E. The first magnetic element 30A is irradiated with the first monitoring light, and the second magnetic element 30B is irradiated with the second monitoring light.

[0142] The optical device 109 according to the tenth embodiment has the same effects as the optical device 100 according to the first embodiment. Moreover, the optical device 109 can measure a change in state of an irradiated object by measuring the intensity of reflected light from the irradiated object using the second magnetic element 30B.

[0143] 26 is a conceptual diagram of an optical system 200 using an optical device 109. The optical system 200 can be implemented in glasses 1000, for example.

[0144] The optical system 200 includes an optical device 109, an optical system 210, drivers 220 and 221, and a controller 230. The optical system 210 includes, for example, a collimator lens 211, a slit 212, an ND filter 213, and an optical scanning mirror 214. The optical system 210 guides the light output from the optical device 109 to an object to be irradiated (the eye in this example). The optical scanning mirror 214 is, for example, a two-axis MEMS mirror that changes the reflection direction of the laser light to the horizontal and vertical directions. The optical system 210 is an example, and is not limited to this example. The driver 220 controls the output of each of the laser diodes 11, 12, 13, and 14. The driver 221 is a control system that drives the optical scanning mirror 214. The controller 230 controls the drivers 220 and 221.

[0145] Light L output from laser diodes 11, 12, 13, and 14 of an optical device 109 G The light propagates through the optical system 210, is reflected by the lenses of the glasses 1000, and enters the eye. Here, an example is shown in which the light is reflected by the lenses of the glasses 1000, but the light may be directly irradiated onto the eye.

[0146] Red, green, and blue light L emitted from laser diodes 11, 12, and 13, respectively. G displays an image. The image can be freely controlled by adjusting the output intensity of each of the laser diodes 11, 12, and 13. The output intensity of each of the laser diodes 11, 12, and 13 can be adjusted based on the measurement result of the output from the first magnetic element 30A to which the visible light output from each of the laser diodes 11, 12, and 13 is irradiated. Alternatively, the output of the laser diodes 11, 12, and 13 may be kept constant, and the intensity of each light reaching the multiplexing path 24A may be adjusted using an optical modulation element.

[0147] 27 is a plan view of an optical device according to a modified example, seen from the z direction. In an optical device 109A, each of input waveguides 21, 22, and 23 has an optical modulation element 90.

[0148] Fig. 28 is a plan view of an optical modulation element 90. Fig. 28 also illustrates power sources 91 and 92 and a termination resistor R. The optical modulation element 90 includes a waveguide 70 and electrodes 81, 82, 83, and 84. The optical modulation element 90 shown in Fig. 28 is an example of an optical modulation element, and is not limited to this example.

[0149] The input light inputted from the waveguide 73 is branched at the branching portion 75 and propagates in the first waveguide 71 and the second waveguide 772. The phase difference between the light propagating in the first waveguide 71 and the light propagating in the second waveguide 72 is zero when the light is branched.

[0150] When a voltage is applied between the electrodes 81 and 82, an electric field is applied to the first waveguide 71 and the second waveguide 72, and the refractive indexes of the first waveguide 71 and the second waveguide 72 change due to the electro-optic effect. When the refractive indexes of the first waveguide 71 and the second waveguide 72 differ, a phase difference occurs between the light propagating through the first waveguide 71 and the light propagating through the second waveguide 72. The light propagating through the first waveguide 71 and the second waveguide 72 join at the coupling portion 76 and are output from the waveguide 74.

[0151] The output light is a combination of the light propagating through the first waveguide 71 and the light propagating through the second waveguide 72. The intensity of the output light varies according to the phase difference between the light propagating through the first waveguide 71 and the light propagating through the second waveguide 72. For example, when the phase difference is an even multiple of π, the lights strengthen each other, and when the phase difference is an odd multiple of π, the lights weaken each other. In this way, by using the optical modulation element 90, the intensity of each light reaching the multiplexer 24 can be adjusted while keeping the output of the laser diodes 11, 12, and 13 constant. The configuration in which the optical modulation element 90 is used to adjust the intensity of the light can reduce power consumption more than the configuration in which the output of the laser diodes 11, 12, and 13 is directly adjusted. The configuration in which the optical modulation element 90 is applied to the input waveguides 21, 22, and 23 can also be applied to the optical devices according to the first to ninth embodiments.

[0152] In the optical modulation element 90, the waveguide 70 may further include a monitoring waveguide connected to the waveguide 74, and a magnetic element at the end of the output end of the monitoring waveguide. This magnetic element is similar to the magnetic element 30 described above. By using the magnetic element 30, the intensity of the light propagating through the waveguide 74 can be monitored.

[0153] The near-infrared light emitted from the laser diode 14 of the optical device 109 is reflected by the pupil of the eye. R Is, Light L G The reflected light L , which is near-infrared light, passes through the same optical axis as the reflected light L , and reaches the optical device 109. R At least a part of the reflected light L propagates through the second monitoring waveguide 26E from the output end of the output waveguide 25 and is irradiated to the second magnetic element 30B. R The optical system 200 measures the intensity of the near-infrared light L irradiated at the position adjusted by the optical scanning mirror 214. R The movement of the gaze point (point of gaze) can be identified from the intensity of the reflected light L R is not limited to light reflected from the pupil of the eye, but may be light reflected from the cornea of ​​the eye or light reflected from the sclera of the eye.

[0154] Here, a system capable of both image display and eye tracking has been illustrated as an example of an optical system, but the optical system is not limited to this example.

[0155] For example, the laser diode 14 for eye tracking may be removed from the optical system described above. In this case, the optical system becomes a system for image display. In this case, the optical devices 100 to 108 according to the first to ninth embodiments can be used instead of the optical device 109.

[0156] Also, for example, the laser diodes 11, 12, and 13 for image display may be removed from the above optical system. In this case, the optical system becomes a system dedicated to eye tracking. FIG. 29 is a plan view showing an example of an optical device 110 that can be used in a system dedicated to eye tracking. The optical device 110 has a laser diode 14, an optical waveguide 20E, and a magnetic element 30. The optical waveguide 20E has an input waveguide 21A, an output waveguide 25, and a second monitoring waveguide 26E. At least a part of the light propagating through the output waveguide 25 is irradiated to the magnetic element 30 via the second monitoring waveguide 26E. At least a part of the light outputted from the output waveguide 25 to the outside and reflected by the irradiated object is irradiated to the magnetic element 30 via the second monitoring waveguide 26E.

[0157] As described above, the present invention is not limited to the above-mentioned embodiment and modifications, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. For example, the characteristic configurations of the above-mentioned embodiment and modifications may be combined with each other. [Explanation of symbols]

[0158] 11, 12, 13, 14...Laser diode 20,20A,20B,20C,20D,20E…Waveguide 21, 22, 23, 21A...Input waveguide 24…Combination route 25,25A,25B,25C…Output waveguide 26, 26A, 26B, 26C, 26D, 26E...Monitoring waveguide 27, 27A…Board 30...Magnetic element 30A…First magnetic element 30B...Second magnetic element 50…Reflector 60...Support 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 10...Optical devices 200...Optical system L…Monitoring light

Claims

1. 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; a waveguide; the waveguide includes at least one input waveguide optically connected to the laser diode and an output waveguide connected to the input waveguide; At least a portion of light propagating through at least one of the input waveguide and the output waveguide is irradiated onto the magnetic element; An optical device, wherein an output voltage from the magnetic element changes according to the intensity of light irradiated onto the first ferromagnetic layer when the light is irradiated onto the first ferromagnetic layer.

2. The optical device of claim 1 , wherein the waveguide comprises lithium niobate as a primary component.

3. Further comprising a substrate; The waveguide is formed on the substrate; The optical device of claim 1 , wherein the substrate comprises aluminum oxide.

4. Further comprising a substrate; The waveguide is formed on the substrate; An optical device according to any one of claims 1 to 3, wherein the magnetic element is on or above the substrate.

5. Further comprising a reflector, The optical device according to claim 1 , wherein the reflector reflects at least a portion of the light towards the magnetic element.

6. 6. The optical device according to claim 1, wherein at least a portion of the light is irradiated onto the magnetic element in a direction intersecting a stacking direction of the magnetic element.

7. 6. The optical device according to claim 1, wherein at least a portion of the light is irradiated onto the magnetic element from a stacking direction of the magnetic element.

8. 8. The optical device according to claim 1, further comprising a support member that is a member separate from the substrate on which the waveguide is formed and that supports the magnetic element.

9. the waveguide further comprises a monitoring waveguide; the monitoring waveguide is connected to at least one of the input waveguide and the output waveguide; The optical device of claim 1 , wherein at least a portion of the light propagates through the monitoring waveguide.

10. the at least one input waveguide is a plurality of input waveguides; the at least one magnetic element is a plurality of magnetic elements; a plurality of monitoring waveguides connected to respective said input waveguides; The optical device according to claim 1 , wherein each of the magnetic elements is irradiated with light propagating through each of the plurality of monitoring waveguides.

11. the at least one magnetic element is a plurality of magnetic elements; a first magnetic element among the plurality of magnetic elements is irradiated with at least a part of light propagating from the laser diode in a direction toward the input waveguide or the output waveguide through at least one of the input waveguide and the output waveguide; The optical device according to any one of claims 1 to 10, wherein a second magnetic element of the plurality of magnetic elements is irradiated with at least a portion of the light output from the output waveguide and reflected by an irradiated body.

12. The magnetic element comprises: a sense current is caused to flow from the first ferromagnetic layer to the second ferromagnetic layer when the magnetizations of the first ferromagnetic layer and the second ferromagnetic layer are parallel in a state where no light is irradiated; An optical device as described in any one of claims 1 to 11, configured to flow a sense current from the second ferromagnetic layer to the first ferromagnetic layer when the magnetization of the first ferromagnetic layer and the magnetization of the second ferromagnetic layer are anti-parallel in the absence of light irradiation.

13. An optical device according to claim 11; an optical system that guides the light output from the optical device to an object to be illuminated.

Images