Optical Switch and Switching Method

Abstract

Provided is an optical switch having a function for switching the optical path of a signal light in response to a control signal. An optical switch (1A, 1B) comprises a light modulator (12A, 12B) that reflects or refracts signal light (L), the light modulator (12A, 12B) including a plurality of cells in which phase modulation amounts can be set independently from each other. The phase modulation amount of each cell included in the light modulator (12A, 12B) is set so that the signal light (L) is emitted in a direction corresponding to the ratio of a control signal cycle to a carrier light cycle.

Description

Technical Field

[0001] The present invention relates to an optical switch for switching an optical path of signal light and a switching method.

Background Art

[0002] With the increase in data traffic, in optical backbone networks, there is an increasing demand for larger capacity. To meet this demand, the form of optical backbone networks has evolved from point-to-point type through ring type to mesh type. In order to efficiently utilize a mesh-type optical backbone network, it is necessary to quickly switch the path of signal light. As an optical switch capable of quickly switching the path of signal light, an optical switch using DMD (Digital Mirror Device) or an optical switch using LCOS (Liquid Crystal On Silicon) is known. For example, Patent Document 1 discloses an optical switch using LCOS.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an optical network, it may be necessary to switch the path of signal light according to a control signal (for example, specifying the destination of the signal light) superimposed on the signal light. However, an optical switch itself using DMD or LCOS does not have such a function. Therefore, in order to realize such a function, it is necessary to demodulate the control signal from the signal light and control the optical switch according to the control signal. Then, this causes a problem that the device becomes complicated and it becomes difficult to increase the switching speed.

[0005] One aspect of the present invention has been made in view of the above problems, and an object thereof is to realize an optical switch having a function of switching an optical path of signal light in response to a control signal. **Means for Solving the Problems**

[0006] In an optical switch according to one aspect of the present invention, in an optical switch that switches an optical path of signal light obtained by modulating carrier light with a control signal and a data signal, the optical modulation element that reflects or refracts the signal light includes a plurality of cells whose phase modulation amounts can be set independently of each other. The optical modulation element is provided, and the phase modulation amount of each cell included in the optical modulation element is set so that the signal light is emitted in a direction corresponding to the ratio of the period of the control signal to the period of the carrier light. The configuration described above is adopted.

[0007] In a switching method according to one aspect of the present invention, in a switching method for switching an optical path of signal light obtained by modulating carrier light with a control signal and a data signal, an optical modulation element including a plurality of cells whose phase modulation amounts can be set independently of each other is used. And a step of reflecting or refracting the signal light, and the phase modulation amount of each cell included in the optical modulation element is set so that the signal light is emitted in a direction corresponding to the ratio of the period of the control signal to the period of the carrier light. The configuration described above is adopted. **Advantages of the Invention**

[0008] According to one aspect of the present invention, the optical path of the signal light can be switched according to the period of the control signal. **Brief Description of the Drawings**

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0010] (Configuration of Optical Switch) The configuration of the optical switch 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

[0011] The optical switch 1 is a device for switching the optical path of the signal light L obtained by modulating the carrier light L0 with the control signal C and the data signal D. Here, the control signal C is a periodic signal having a period T. In the present embodiment, two types of signal lights L1 and L2 are assumed as the signal light L input to the optical switch 1. The signal light L1 is obtained by modulating the carrier light L0 with the control signal C1 and the data signal D1, and the signal light L2 is obtained by modulating the carrier light L0 with the control signal C2 and the data signal D2.

[0012] FIG. 1 is a waveform diagram illustrating the waveforms of the signal lights L1 to L2.

[0013] In Fig. 1(a), the waveforms of the carrier light L0, the signal light L1' obtained by modulating the carrier light L0 with the control signal C1, and the signal light L1 obtained by modulating the signal light L1' with the data signal D1 are illustrated. In the example shown in Fig. 1(a), the period T1 of the control signal C1 is twice the period T0 of the carrier light L0.

[0014] However, the order of modulation is not limited to this. That is, instead of modulating the carrier light L0 with the control signal C1 and then modulating it with the data signal D1, the carrier light L0 may be modulated with the data signal D1 first and then modulated with the control signal C1.

[0015] In Fig. 1(b), the waveforms of the carrier light L0, the signal light L2' obtained by modulating the carrier light L0 with the control signal C2, and the signal light L2 obtained by modulating the signal light L2' with the data signal D2 are illustrated. In the example shown in Fig. 1(b), the period T2 of the control signal C2 is three times the period T0 of the carrier light L0.

[0016] However, the order of modulation is not limited to this. That is, instead of modulating the carrier light L0 with the control signal C2 and then modulating it with the data signal D2, the carrier light L0 may be modulated with the data signal D2 first and then modulated with the control signal C2.

[0017] Fig. 2(a) is a side view showing the first configuration of the optical switch 1. Hereinafter, the optical switch 1 having the first configuration is also referred to as the optical switch 1A.

[0018] As shown in Fig. 2(a), the optical switch 1A includes an input port 11, an optical modulation element 12A, an output port group 13, and a lens 14.

[0019] The input port 11 is a means for guiding the signal light L before being reflected by the optical modulation element 12A. In the present embodiment, an optical fiber is used as the input port 11. The signal light L emitted from the input port 11 is incident on the optical modulation element 12A.

[0020] The optical modulation element 12A is a means for modulating and reflecting the signal light L, and is composed of a plurality of cells in which the phase modulation amounts are set independently of each other or can be set independently of each other. The optical modulation element 12A may also be called a "spatial light modulator". A configuration example of the optical modulation element 12A will be described later by changing the reference drawing. The phase modulation amount of each cell constituting the optical modulation element 12A is set so as to emit the signal light L in a direction corresponding to the ratio T / T0 of the period T of the control signal C to the period T0 of the carrier light L0. In the illustrated example, it is set as follows.

[0021] When the signal light L is the above-described signal light L1, that is, when the ratio T / T0 is R1 (2 in the example shown in FIG. 1), the optical modulation element 12A reflects the signal light L so that the emission angle becomes θ1. On the other hand, when the signal light L is the above-described signal light L2, that is, when the ratio T / T0 is R2 (3 in the example shown in FIG. 1), the optical modulation element 12A reflects the signal light L so that the emission angle becomes θ2.

[0022] The output port group 13 is composed of a plurality of output ports 131 to 132. The output ports 131 to 132 are means for guiding the signal light L after being reflected by the optical modulation element 12A, respectively. In the present embodiment, optical fibers are used as the output ports 131 to 132.

[0023] The output port 131 is provided on the optical path of the signal light L when the ratio T / T0 is R1 among the signal lights L after being reflected by the optical modulation element 12A. Therefore, when the ratio T / T0 is R1, the signal light L after being reflected by the optical modulation element 12A enters the output port 131 and is guided by the output port 131. On the other hand, the output port 132 is provided on the optical path of the signal light L when the ratio T / T0 is R2 among the signal lights L after being reflected by the optical modulation element 12A. Therefore, when the ratio T / T0 is R2, the signal light L after being reflected by the optical modulation element 12A enters the output port 132 and is guided by the output port 132.

[0024] The lens 14 is a means for condensing the signal light L after being reflected by the optical modulation element 12A. The lens 14 condenses the signal light L after being reflected by the optical modulation element 12A, which is the signal light L when the ratio T / T0 is R1, onto the incident end face of the output port 131. Further, the lens 14 condenses the signal light L after being reflected by the optical modulation element 12A, which is the signal light L when the ratio T / T0 is R2, onto the incident end face of the output port 132. By providing the lens 14, it becomes possible to efficiently make the signal light L after being reflected by the optical modulation element 12A enter the output ports 131 to 132.

[0025] Note that the optical switch 1A may include a plurality of combinations of the input port 11 and the output port group 13. Thereby, a multi-channel optical switch can be realized using a single optical modulation element 12A.

[0026] FIG. 2(b) is a side view showing a second configuration of the optical switch 1. Hereinafter, the optical switch 1 having the second configuration is also referred to as the optical switch 1B.

[0027] As shown in FIG. 2(b), the optical switch 1B includes an input port 11, an optical modulation element 12B, an output port group 13, and a lens 14.

[0028] The input port 11 is a means for guiding the signal light L before passing through the optical modulation element 12B. In the present embodiment, an optical fiber is used as the input port 11. The signal light L emitted from the input port 11 enters the optical modulation element 12B.

[0029] The optical modulation element 12B is a means for modulating and refracting the signal light L, and is composed of a plurality of cells in which the phase modulation amounts are set independently of each other or can be set independently of each other. The optical modulation element 12B may also be called a "spatial light modulator". A configuration example of the optical modulation element 12B will be described later by changing the reference drawing. The phase modulation amount of each cell constituting the optical modulation element 12B is set so as to emit the signal light L in a direction corresponding to the ratio T / T0 of the period T of the control signal C to the period T0 of the carrier light L0. In the illustrated example, it is set as follows.

[0030] When the signal light L is the above-described signal light L1, that is, when the ratio T / T0 is R1 (2 in the example shown in FIG. 1), the optical modulation element 12B refracts the signal light L so that the emission angle becomes θ1. On the other hand, when the signal light L is the above-described signal light L2, that is, when the ratio T / T0 is R2 (3 in the example shown in FIG. 1), the optical modulation element 12B refracts the signal light L so that the emission angle becomes θ2.

[0031] The output port group 13 is composed of a plurality of output ports 131 to 132. The output ports 131 to 132 are means for guiding the signal light L after passing through the optical modulation element 12B, respectively. In the present embodiment, optical fibers are used as the output ports 131 to 132.

[0032] The output port 131 is provided on the optical path of the signal light L when the ratio T / T0 is R1, which is the signal light L refracted by the optical modulation element 12B. Therefore, when the ratio T / T0 is R1, the signal light L refracted by the optical modulation element 12B enters the output port 131 and is guided by the output port 131. On the other hand, the output port 132 is provided on the optical path of the signal light L when the ratio T / T0 is R2, which is the signal light L refracted by the optical modulation element 12B. Therefore, when the ratio T / T0 is R2, the signal light L refracted by the optical modulation element 12B enters the output port 132 and is guided by the output port 132.

[0033] The lens 14 is a means for condensing the signal light L after being refracted by the optical modulation element 12B. The lens 14 condenses the signal light L after being refracted by the optical modulation element 12B, which is the signal light L when the ratio T / T0 is R1, onto the incident end face of the output port 131. Further, the lens 14 condenses the signal light L after being refracted by the optical modulation element 12B, which is the signal light L when the ratio T / T0 is R2, onto the incident end face of the output port 132. By providing the lens 14, it becomes possible to efficiently make the signal light L after being refracted by the optical modulation element 12B incident on the output ports 131 to 132.

[0034] Note that the optical switch 1B may include a plurality of combinations of the input port 11 and the output port group 13. Thereby, a multi-channel optical switch can be realized using a single optical modulation element 12B.

[0035] (Configuration example of a reflective optical modulation element) A configuration example of the reflective optical modulation element 12A included in the optical switch 1A will be described with reference to FIG. 3. FIG. 3(a) is a plan view of the optical modulation element 12A according to this specific example. FIG. 3(b) is a cross-sectional view of the microcell C constituting the optical modulation element 12A according to this specific example.

[0036] As shown in FIG. 3(a), the optical modulation element 12A is composed of a plurality of microcells C whose phase modulation amounts can be set independently of each other. When the signal light L is incident on the optical modulation element 12A, the signal light L reflected by each microcell C while being phase-modulated interferes with each other, thereby forming the signal light L that exits in a direction corresponding to the ratio T / T0. The phase modulation amount of each microcell C may be variable or fixed, but in this configuration example, it is variable.

[0037] In this specification, "microcell" refers to, for example, a cell with a cell size of less than 10 μm. Also, "cell size" refers to the square root of the area of the cell. For example, when the planar shape of microcell C is square, the cell size of microcell C is the length of one side of microcell C. The lower limit of the cell size of microcell C is, for example, 1 nm.

[0038] The optical modulation element 12A illustrated in Fig. 3(a) is composed of 200×200 microcells C arranged in a matrix. The planar shape of each microcell C is a square of 500 nm×500 nm, and the planar shape of the optical modulation element 12A is a square of 100 μm×100 μm.

[0039] Each microcell C constituting the optical modulation element 12A can be composed of, for example, a polarizing plate C11, a reflector C12, a first electrode C13, a magnetically free layer C14, an insulating layer C15, a magnetically fixed layer C16, and a second electrode C17, as shown in Fig. 3(b).

[0040] The polarizing plate C11 and the reflector C12 are arranged to face each other. The first electrode C13, the magnetically free layer C14, the insulating layer C15, the magnetically fixed layer C16, and the second electrode C17 are laminated in this order and sandwiched between the polarizing plate C11 and the reflector C12. Here, the lamination direction of the first electrode C13, the magnetically free layer C14, the insulating layer C15, the magnetically fixed layer C16, and the second electrode C17 is orthogonal to the lamination direction of the polarizing plate C11 and the reflector C12. Therefore, the first side surface of the magnetically free layer C14 is in surface contact with one main surface of the polarizing plate C11, and the second side surface of the magnetically free layer C14 facing the first side surface is in surface contact with one main surface of the reflector C12. The signal light L (1) enters the inside of the magnetically free layer C14 through the polarizing plate C11, (2) is reflected by the reflector C12, and (3) exits the outside of the magnetically free layer C14 through the polarizing plate C11.

[0041] The magnetically free layer C14 is composed of, for example, a soft magnetic material (e.g., CoFeB) having conductivity and translucency. Further, the magnetically fixed layer C16 is composed of, for example, a hard magnetic material (e.g., permalloy) having conductivity. Further, as the polarizing plate C11, a polarizing plate that selectively transmits a polarization component whose polarization direction P is parallel to the magnetization direction M of the magnetically fixed layer C16 is selected. In FIG. 3(b), the case where the magnetization direction M and the polarization direction P are parallel to both the main surface of the polarizing plate C11 and the main surface of the magnetically fixed layer C16 is illustrated.

[0042] When a potential difference is applied between the first electrode C13 and the second electrode C17, a spin current (flow of spin-polarized electrons) is injected from the magnetically fixed layer C16 to the magnetically free layer C14 through the insulating layer C15 due to the tunnel effect, and magnetization occurs in the magnetically free layer C14. Here, the magnetization generated in the magnetically free layer C14 is magnetization parallel to the magnetization direction M of the magnetically fixed layer C16, that is, magnetization parallel to the polarization direction P of the signal light incident on the magnetically free layer C14 through the polarizing plate C11. Therefore, the phase of the signal light is delayed by the transverse Kerr effect in the process of propagating through the magnetically free layer C14.

[0043] Here, the amount of phase change of the signal light in the cell C is determined according to the magnitude of the magnetization generated in the magnetically free layer C14. Further, the magnitude of the magnetization generated in the magnetically free layer C14 is determined according to the magnitude of the spin current injected into the magnetically free layer C14. Further, the magnitude of the spin current injected into the magnetically free layer C14 is determined according to the potential difference applied between the first electrode C13 and the second electrode C17. Therefore, by controlling the potential difference applied between the first electrode C13 and the second electrode C17, the phase modulation of the cell C can be set to a desired value.

[0044] As described above, the optical modulation element 12A is composed of a plurality of cells C that perform phase modulation by spin injection into the magnetically free layer C14. Therefore, it is possible to switch the optical path of the signal light L faster than DMD or LCOS.

[0045] In this configuration example, although the cell C having the same configuration as the STT (Spin Transfer Torque) type MRAM (Magnetoresistive Random Access Memory) has been described, it is not limited thereto. For example, a cell C having the same configuration as the SOT (Spin Orbit Torque) type MRAM may be used. Such a cell C can be realized, for example, by removing the insulating layer C15, the magnetization fixed layer C16, and the second electrode C17 from the structure shown in FIG. 3(b). In this case, for example, by including a heavy metal in the first electrode C13 and applying a pulse voltage or a pulse current to the first electrode C13, a spin current can be efficiently injected into the magnetization free layer C14.

[0046] Note that the reflective optical modulation element 12A can also be configured by a plurality of microcells C in which the phase modulation amounts are set independently of each other, that is, the thicknesses or refractive indexes are set independently of each other. FIG. 4 is a perspective view showing an enlarged part of the optical modulation element 12A configured by a plurality of microcells C in which the thicknesses are set independently of each other.

[0047] The optical modulation element 12A shown in FIG. 4 is composed of a reflector 121 and a plurality of pillars formed on the upper surface of the reflector 121. Each pillar is a quadrangular prism-shaped structure having a square bottom surface with the length of each side equal to the cell size, and functions as a microcell C.

[0048] The signal light L (1) enters from the upper surface of the pillar, (2) passes through the pillar, (3) is reflected by the reflector 121, (4) passes through the pillar, and (5) exits from the upper surface of the pillar. The phase modulation amount of the signal light L reflected by each microcell C is determined according to the height of the pillar constituting the microcell C. That is, the phase modulation amount of the signal light L reflected by the microcell C constituted by the pillar with a high height becomes large, and the phase modulation amount of the signal light reflected by the microcell C constituted by the pillar with a low height becomes small. Note that the phase modulation amount of each microcell C is fixed.

[0049] The optical modulation element 12A shown in FIG. 4 can also switch the optical path of the signal light L faster than DMD or LCOS.

[0050] (Configuration example of transmissive optical modulation element) A configuration example of the transmissive optical modulation element 12B included in the optical switch 1B will be described with reference to FIG. 5. FIG. 5(a) is a plan view of the optical modulation element 12B according to this specific example. FIG. 5(b) is a cross-sectional view of the microcell C constituting the optical modulation element 12B according to this specific example.

[0051] As shown in FIG. 5(a), the optical modulation element 12B is composed of a plurality of microcells C whose phase modulation amounts can be set independently of each other. When the signal light L is incident on the optical modulation element 12B, the signal light L that has passed through each microcell C while being phase-modulated interferes with each other, thereby forming the signal light L that is emitted in a direction corresponding to the ratio T / T0. The phase modulation amount of each microcell C may be variable or fixed, but in this configuration example, it is variable.

[0052] The optical modulation element 12B illustrated in FIG. 5(a) is composed of 200×200 microcells C arranged in a matrix. The planar shape of each microcell C is a square with a size of 500 nm×500 nm, and the planar shape of the optical modulation element 12B is a square with a size of 100 μm×100 μm.

[0053] Each microcell C constituting the optical modulation element 12B can be composed of, for example, a polarizing plate C11, a polarizing plate C18, a first electrode C13, a magnetically free layer C14, an insulating layer C15, a magnetically fixed layer C16, and a second electrode C17, as shown in FIG. 5(b).

[0054] The polarizing plates C11 and C18 are arranged to face each other. The first electrode C13, the magnetically free layer C14, the insulating layer C15, the magnetically fixed layer C16, and the second electrode C17 are laminated in this order and sandwiched between the polarizing plates C11 and C18. Here, the lamination direction of the first electrode C13, the magnetically free layer C14, the insulating layer C15, the magnetically fixed layer C16, and the second electrode C17 is orthogonal to the lamination direction of the polarizing plates C11 and C18. For this reason, the first side surface of the magnetically free layer C14 is in surface contact with one main surface of the polarizing plate C11, and the second side surface of the magnetically free layer C14 facing the first side surface is in surface contact with one main surface of the polarizing plate C18. The signal light L (1) enters the inside of the magnetically free layer C14 through the polarizing plate C11, (2) passes through the magnetically free layer C14, and (3) exits the outside of the magnetically free layer C14 through the polarizing plate C18.

[0055] The magnetically free layer C14 is made of, for example, a soft magnetic material (e.g., CoFeB) having conductivity and translucency. The magnetically fixed layer C16 is made of, for example, a hard magnetic material (e.g., permalloy) having conductivity. As the polarizing plates C11 and C18, a polarizing plate that selectively transmits a polarization component whose polarization direction P is parallel to the magnetization direction M of the magnetically fixed layer C16 is selected. In FIG. 5(b), the case where the magnetization direction M and the polarization direction P are parallel to both the main surface of the polarizing plate C11 and the main surface of the magnetically fixed layer C16 is illustrated.

[0056] When a potential difference is applied between the first electrode C13 and the second electrode C17, a spin current (a flow of spin-polarized electrons) is injected from the magnetically fixed layer C16 into the magnetically free layer C14 through the insulating layer C15 due to the tunnel effect, and magnetization occurs in the magnetically free layer C14. Here, the magnetization generated in the magnetically free layer C14 is magnetization parallel to the magnetization direction M of the magnetically fixed layer C16, that is, magnetization parallel to the polarization direction P of the signal light incident on the magnetically free layer C14 through the polarizing plate C11. For this reason, the phase of the signal light is delayed by the transverse Kerr effect in the process of propagating through the magnetically free layer C14.

[0057] Here, the amount of phase change of the signal light in cell C is determined according to the magnitude of the magnetization generated in the free magnetization layer C14. Further, the magnitude of the magnetization generated in the free magnetization layer C14 is determined according to the magnitude of the spin current injected into the free magnetization layer C14. Further, the magnitude of the spin current injected into the free magnetization layer C14 is determined according to the potential difference applied between the first electrode C13 and the second electrode C17. Therefore, by controlling the potential difference applied between the first electrode C13 and the second electrode C17, the phase modulation of cell C can be set to a desired value.

[0058] As described above, the optical modulation element 12B is composed of a plurality of microcells C that perform phase modulation by injecting spins into the free magnetization layer C14. Therefore, it is possible to switch the optical path of the signal light L faster than DMD or LCOS.

[0059] In this configuration example, the cell C having the same configuration as that of the STT (Spin Transfer Torque) type MRAM (Magnetoresistive Random Access Memory) has been described, but the present invention is not limited thereto. For example, a cell C having the same configuration as that of the SOT (Spin Orbit Torque) type MRAM may be used. Such a cell C can be realized, for example, by removing the insulating layer C15, the magnetization fixed layer C16, and the second electrode C17 from the structure shown in FIG. 5(b). In this case, for example, by including a heavy metal in the first electrode C13 and applying a pulse voltage or a pulse current to the first electrode C13, a spin current can be efficiently injected into the free magnetization layer C14.

[0060] The reflective optical modulation element 12B can also be composed of a plurality of microcells C in which the phase modulation amounts are set independently of each other, that is, the thicknesses or refractive indexes are set independently of each other. FIG. 6 is a perspective view showing an enlarged part of the optical modulation element 12B composed of a plurality of microcells C in which the thicknesses are set independently of each other.

[0061] The optical modulation element 12B shown in FIG. 6 is composed of a transparent substrate 122 and a plurality of pillars formed on the upper surface of the transparent substrate 122. Each pillar is a quadrangular prism-shaped structure having a square bottom surface with the length of each side equal to the cell size, and functions as a microcell C. The signal light L (1) enters from the upper surface of the pillar, (2) passes through the pillar, (3) passes through the transparent substrate 122, and (4) exits from the lower surface of the transparent substrate 122. The amount of phase modulation of the signal light L passing through each microcell C is determined according to the height of the pillar constituting the microcell C. That is, the amount of phase modulation of the signal light L passing through the microcell C composed of a pillar with a high height becomes large, and the amount of phase modulation of the signal light L passing through the microcell C composed of a pillar with a low height becomes small. Note that the amount of phase modulation of each microcell C is fixed.

[0062] Also with the optical modulation element 12B shown in FIG. 6, it is possible to switch the optical path of the signal light L faster than DMD or LCOS.

[0063] (Modification example of optical switch) A modification example of the optical switch 1A (hereinafter referred to as the optical switch 1A') will be described with reference to FIG. 7(a). FIG. 7(a) is a perspective view showing the configuration of the optical switch 1A'.

[0064] The optical switch 1A' is configured in the same manner as the optical switch 1A, except that it includes an optical modulation element 12A' instead of the optical modulation element 12A and includes output port groups 13a to 13c instead of the output port group 13.

[0065] The optical modulation element 12A' is a means for modulating and reflecting the signal light L, and is composed of a plurality of cells whose phase modulation amounts can be set independently of each other. The phase modulation amount of each cell constituting the optical modulation element 12A' is set so that the signal light L is emitted in a direction according to the ratio T / T0 of the period T of the control signal C to the wavelength λ of the carrier light L0 and the period T0 of the carrier light L0. In the illustrated example, it is set as follows.

[0066] When the wavelength λ of the carrier light L0 is λa, the optical modulation element 12A' reflects the signal light L in the in-plane direction of the plane Pa. In particular, when the signal light L is the signal light L1 described above, that is, when the ratio T / T0 is R1 (2 in the example shown in FIG. 1), the optical modulation element 12A' reflects the signal light L so that the emission angle in the plane Pa is θ1. On the other hand, when the signal light L is the signal light L2 described above, that is, when the ratio T / T0 is R2 (3 in the example shown in FIG. 1), the optical modulation element 12A' reflects the signal light L so that the emission angle in the plane Pa is θ2.

[0067] When the wavelength λ of the carrier light L0 is λb, the optical modulation element 12A' reflects the signal light L in the in-plane direction of the plane Pb. In particular, when the signal light L is the signal light L1 described above, that is, when the ratio T / T0 is R1 (2 in the example shown in FIG. 1), the optical modulation element 12A' reflects the signal light L so that the emission angle in the plane Pb is θ1. On the other hand, when the signal light L is the signal light L2 described above, that is, when the ratio T / T0 is R2 (3 in the example shown in FIG. 1), the optical modulation element 12A' reflects the signal light L so that the emission angle in the plane Pb is θ2.

[0068] When the wavelength λ of the carrier light L0 is λc, the optical modulation element 12A' reflects the signal light L in the in-plane direction of the plane Pc. In particular, when the signal light L is the signal light L1 described above, that is, when the ratio T / T0 is R1 (2 in the example shown in FIG. 1), the optical modulation element 12A' reflects the signal light L so that the emission angle in the plane Pc is θ1. On the other hand, when the signal light L is the signal light L2 described above, that is, when the ratio T / T0 is R2 (3 in the example shown in FIG. 1), the optical modulation element 12A' reflects the signal light L so that the emission angle in the plane Pc is θ2.

[0069] The output port group 13a is disposed on the optical path of the signal light L that has been reflected by the optical modulation element 12A' and has a wavelength λ of λa. The output port group 13a is composed of an output port provided on the optical path of the signal light L when the ratio T / T0 is R1 and an output port provided on the optical path of the signal light L when the ratio T / T0 is R2.

[0070] The output port group 13b is disposed on the optical path of the signal light L that has been reflected by the optical modulator 12A' and has a wavelength λ of λb. The output port group 13b is composed of an output port provided on the optical path of the signal light L when the ratio T / T0 is R1 and an output port provided on the optical path of the signal light L when the ratio T / T0 is R2.

[0071] The output port group 13c is disposed on the optical path of the signal light L that has been reflected by the optical modulator 12A' and has a wavelength λ of λc. The output port group 13c is composed of an output port provided on the optical path of the signal light L when the ratio T / T0 is R1 and an output port provided on the optical path of the signal light L when the ratio T / T0 is R2.

[0072] According to the optical switch 1A', in addition to switching the optical path of the signal light L according to the period T of the control signal C, the optical path of the signal light L can be switched according to the wavelength λ of the signal light L. Further, when the signal light L is wavelength multiplexed, each wavelength component included in the signal light L can be separated.

[0073] A modified example of the optical switch 1B (hereinafter referred to as the optical switch 1B') will be described with reference to FIG. 7(b). FIG. 7(b) is a perspective view showing the configuration of the optical switch 1B'.

[0074] The optical switch 1B' is configured in the same manner as the optical switch 1B, except that it includes an optical modulator 12B' instead of the optical modulator 12B and includes output port groups 13a to 13c instead of the output port group 13.

[0075] The optical modulation element 12B’ is a means for modulating and refracting the signal light L, and is composed of a plurality of cells whose phase modulation amounts can be set independently of each other. The phase modulation amount of each cell constituting the optical modulation element 12B’ is set so that the signal light L is emitted in a direction corresponding to the ratio T / T0 of the period T of the control signal C to the wavelength λ of the carrier light L0 and the period T0 of the carrier light L0. In the illustrated example, it is set as follows.

[0076] When the wavelength λ of the carrier light L0 is λa, the optical modulation element 12B’ refracts the signal light L in the in-plane direction of the plane Pa. In particular, when the signal light L is the above-described signal light L1, that is, when the ratio T / T0 is R1 (2 in the example shown in FIG. 1), the optical modulation element 12B’ refracts the signal light L so that the emission angle in the plane PB is θ1. On the other hand, when the signal light L is the above-described signal light L2, that is, when the ratio T / T0 is R2 (3 in the example shown in FIG. 1), the optical modulation element 12B’ refracts the signal light L so that the emission angle in the plane Pa is θ2.

[0077] When the wavelength λ of the carrier light L0 is λb, the optical modulation element 12B’ refracts the signal light L in the in-plane direction of the plane Pb. In particular, when the signal light L is the above-described signal light L1, that is, when the ratio T / T0 is R1 (2 in the example shown in FIG. 1), the optical modulation element 12B’ refracts the signal light L so that the emission angle in the plane Pb is θ1. On the other hand, when the signal light L is the above-described signal light L2, that is, when the ratio T / T0 is R2 (3 in the example shown in FIG. 1), the optical modulation element 12B’ refracts the signal light L so that the emission angle in the plane Pb is θ2.

[0078] When the wavelength λ of the carrier light L0 is λc, the optical modulation element 12B' refracts the signal light L in the in-plane direction of the plane Pc. In particular, when the signal light L is the above-described signal light L1, that is, when the ratio T / T0 is R1 (2 in the example shown in FIG. 1), the optical modulation element 12B' refracts the signal light L so that the emission angle in the plane Pc becomes θ1. On the other hand, when the signal light L is the above-described signal light L2, that is, when the ratio T / T0 is R2 (3 in the example shown in FIG. 1), the optical modulation element 12B' refracts the signal light L so that the emission angle in the plane Pc becomes θ2.

[0079] The output port group 13a is disposed on the optical path of the signal light L that has been reflected by the optical modulation element 12B' and has a wavelength λ of λa. The output port group 13a is composed of an output port provided on the optical path of the signal light L when the ratio T / T0 is R1 and an output port provided on the optical path of the signal light L when the ratio T / T0 is R2.

[0080] The output port group 13b is disposed on the optical path of the signal light L that has been reflected by the optical modulation element 12B' and has a wavelength λ of λb. The output port group 13b is composed of an output port provided on the optical path of the signal light L when the ratio T / T0 is R1 and an output port provided on the optical path of the signal light L when the ratio T / T0 is R2.

[0081] The output port group 13c is disposed on the optical path of the signal light L that has been reflected by the optical modulation element 12B' and has a wavelength λ of λc. The output port group 13c is composed of an output port provided on the optical path of the signal light L when the ratio T / T0 is R1 and an output port provided on the optical path of the signal light L when the ratio T / T0 is R2.

[0082] According to the optical switch 1B', in addition to switching the optical path of the signal light L according to the period T of the control signal C, the optical path of the signal light L can be switched according to the wavelength λ of the carrier light L0. Further, when the signal light L is wavelength-division multiplexed, each wavelength component included in the signal light L can be separated.

[0083] (Summary) In the optical switch according to Embodiment 1 of the present invention, in an optical switch that switches the optical path of signal light obtained by modulating the carrier light with a control signal and a data signal, there is provided an optical modulation element that reflects or refracts the signal light, the optical modulation element including a plurality of cells whose phase modulation amounts can be set independently of each other, and the phase modulation amount of each cell included in the optical modulation element is set so as to emit the signal light in a direction corresponding to the ratio of the period of the control signal to the period of the carrier light. Such a configuration is adopted.

[0084] According to the above configuration, the optical path of the signal light can be switched according to the period of the control signal.

[0085] In the optical switch according to Embodiment 2 of the present invention, in addition to the configuration of Embodiment 1, the phase modulation amount of each cell included in the optical modulation element is set so as to emit the signal light in a direction corresponding to the wavelength of the carrier light and the ratio. Such a configuration is adopted.

[0086] According to the above configuration, in addition to switching the optical path of the signal light according to the period of the control signal, the optical path of the signal light can be switched according to the wavelength of the signal light.

[0087] In the optical switch according to Embodiment 3 of the present invention, in addition to the configuration of Embodiment 1 or 2, there are further provided an input port for guiding the signal light before being reflected or refracted by the optical modulation element and a plurality of output ports for guiding the signal light after being reflected or refracted by the optical modulation element. Such a configuration is adopted.

[0088] According to the above configuration, the output port through which the signal light is guided can be switched according to the period of the control signal.

[0089] In the optical switch according to Embodiment 4 of the present invention, in addition to the configuration of any one of Embodiments 1 to 3, the optical modulation element is a reflective optical modulation element, and the phase modulation amount of each cell included in the optical modulation element is such that the signal light is reflected in a direction corresponding to the ratio of the period of the control signal to the period of the carrier light. Such a configuration is adopted.

[0090] According to the above configuration, a reflective optical switch capable of switching the optical path of the signal light according to the period of the control signal can be realized.

[0091] In the optical switch according to Embodiment 5 of the present invention, in addition to the configuration of any one of Embodiments 1 to 3, the optical modulation element is a transmissive optical modulation element, and the phase modulation amount of each cell included in the optical modulation element is such that the signal light is refracted in a direction corresponding to the ratio of the period of the control signal to the period of the carrier light. Such a configuration is adopted.

[0092] According to the above configuration, a transmissive optical switch capable of switching the optical path of the signal light according to the period of the control signal can be realized.

[0093] In the optical switch according to Embodiment 6 of the present invention, in addition to the configuration of any one of Embodiments 1 to 5, each of the plurality of cells performs phase modulation by spin injection into the magnetization-free layer. Such a configuration is adopted.

[0094] According to the above configuration, the optical path of the signal light can be switched at high speed according to the period of the control signal.

[0095] In the switching method according to Embodiment 7 of the present invention, in a switching method of switching the optical path of signal light obtained by modulating carrier light with a control signal and a data signal, the method includes a step of reflecting or refracting the signal light using an optical modulation element including a plurality of cells whose phase modulation amounts can be set independently of each other, and the phase modulation amount of each cell included in the optical modulation element is set so that the signal light is emitted in a direction corresponding to the ratio of the period of the control signal to the period of the carrier light. Such a configuration is adopted.

[0096] According to the above configuration, the optical path of the signal light can be switched according to the period of the control signal.

[0097] (Supplementary matters) The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means included in the above-described embodiments are also included in the technical scope of the present invention.

Description of reference numerals

[0098] 1A, 1B, 1A’, 1B’ optical switches 11 input ports 12A, 12A’, 12B, 12B’ optical modulation elements 13, 13a, 13b, 13c output port groups

Claims

1. In an optical switch that switches the optical path of signal light obtained by modulating a carrier light with a control signal and a data signal, The optical modulation element that reflects or refracts the signal light, and includes an optical modulation element including a plurality of cells whose phase modulation amounts can be set independently of each other, The phase modulation amount of each cell included in the optical modulation element is set so that the signal light is emitted in a direction corresponding to the ratio of the period of the control signal to the period of the carrier light. An optical switch characterized by the above.

2. The phase modulation amount of each cell included in the optical modulation element is set so that the signal light is emitted in a direction corresponding to the wavelength of the carrier light and the ratio. The optical switch according to claim 1, characterized by the above.

3. An input port that guides the signal light before being reflected or refracted by the optical modulation element, The optical switch according to claim 1 or 2, further comprising a plurality of output ports that guide the signal light after being reflected or refracted by the optical modulation element.

4. The optical modulation element is a reflective optical modulation element, The phase modulation amount of each cell included in the optical modulation element is set so that the signal light is reflected in a direction corresponding to the ratio of the period of the control signal to the period of the carrier light. The optical switch according to claim 1 or 2, characterized by the above.

5. The optical modulation element is a transmissive optical modulation element, The phase modulation amount of each cell included in the optical modulation element is set so that the signal light is refracted in a direction corresponding to the ratio of the period of the control signal to the period of the carrier light. The optical switch according to claim 1 or 2, characterized by the above.

6. Each of the plurality of cells performs phase modulation by spin injection into a magnetization-free layer. The optical switch according to claim 1 or 2, characterized by the above.

7. In a switching method for switching the optical path of signal light obtained by modulating a carrier light with a control signal and a data signal, Using an optical modulation element including a plurality of cells whose phase modulation amounts can be set independently of each other, and including a step of reflecting or refracting the signal light, The phase modulation amount of each cell included in the optical modulation element is set so that the signal light is emitted in a direction corresponding to the ratio of the period of the control signal to the period of the carrier light. A switching method characterized by the above.

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