JP2002350908A - Ray deflector using photonic crystal, optical switch suing this device and ray deflection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized ray deflector which uses photonic crystals and is capable of deflecting the incident rays on the photonic crystals at a controlled deflection angle and outputting the transmitted rays having a desired direction from the photonic crystals. SOLUTION: This ray deflector consists of the photonic crystals designed to have photonic band gap wavelengths different from the wavelength of the incident rays and provides the transmitted rays forming the desired angle with the incident rays by impressing energy to the photonic crystals and deflecting the incident rays made incident on the surfaces of the photonic crystals from the other surfaces of the photonic crystals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light beam deflecting device using a photonic crystal, an optical switch using the same, and a light beam deflecting method.

[0002]

2. Description of the Related Art A photonic crystal is a multidimensional periodic structure in which two or more materials having different dielectric constants are periodically arranged at intervals of about the wavelength of light, and the controllability of light is greatly increased. R & D is being vigorously pursued as a next-generation optical technology because of the expectation that it will be able to be improved.

For example, an optical switch using a photonic crystal having a two-dimensional periodic structure is disclosed in JP-A-10-90634.
No., published in Japanese Unexamined Patent Publication No. This optical switch, as shown in FIG. 17, has a light beam (=
This is for switching between an ON state (transmission) in which an incident light beam transmits through the photonic crystal and an OFF state (reflection) in which the transmission of the incident light is blocked.

That is, two optical fibers 12a, 12a
b provides the collimator lenses 14a, 1
4b and the photonic crystal 1 ′ via the polarizers 15a and 15b. This optical switch comprises a circular polarizer 22.
Means for irradiating the control light 21 to the photonic crystal 1 ′ through the interface, and changing the ON / OFF state by changing the photonic band structure of the photonic crystal 1 ′ by the irradiation of the control light 21. It has become. The transmitted light that has passed through the photonic crystal 1 ′ in the ON state is output via the polarizers 16a and 16b.

[0005]

As described above, the above-mentioned optical switch has a structure in which the incident light is transmitted through the photonic crystal.
The purpose is to switch between the N state and the OFF state in which incident light is reflected by the photonic crystal, and therefore, merely provides the presence or absence of transmitted light as an output.
This narrows the field of use of the optical switch.

On the other hand, if the direction of the transmitted light provided from the photonic crystal can be controlled by deflecting the light beam incident on the photonic crystal, the input end receiving the incident light and each transmitting light from the photonic crystal can be controlled. There is a possibility that a novel optical switch using a photonic crystal having a plurality of output terminals that can be provided can be realized. Such a new optical switch can be used for a wide range of applications, since the transmitted light can be output from a desired one of the output ends by controlling the deflection of the incident light. right.

[0007]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to deflect a light beam incident on one side of a photonic crystal at a controlled angle and to transmit a transmitted light beam having a desired direction to the photonic crystal. Another object of the present invention is to provide a small beam deflecting device using a photonic crystal, which can output from the other side.

[0008] That is, this light beam deflecting device includes a photonic crystal designed to have a photonic band gap wavelength different from the wavelength of an incident light beam, an energy applied to the photonic crystal, and Deflection control means for deflecting a light beam incident on the incident side and providing a transmitted light beam at a desired angle to the light beam from a side other than the incident side of the photonic crystal.

When the photonic crystal is composed of at least two kinds of materials having different refractive indexes, it is preferable that the control means controls the ratio of the refractive indexes between the materials by applying the energy. Alternatively, when at least one of the materials constituting the photonic crystal is an electro-optic material, the control means preferably applies an electric field to the photonic crystal as energy. In these cases, no mechanical external force is applied to the photonic crystal as the energy. Therefore, the light beam deflecting device can be operated stably for a long time. further,
Since the deflection control means changes the deflection angle of the incident light beam, when the intensity of the electric field applied to the photonic crystal is electrically controlled, it is possible to provide a small-sized light beam deflection device having a high-speed response.

Another object of the present invention is to provide a novel optical switch using the above-described light beam deflecting device, which can prevent optical signal crosstalk and can ensure high transmission efficiency. That is, this optical switch is provided on the above-described light beam deflecting device, the light incident side of the photonic crystal, and an optical input terminal through which a light beam (= incident light beam) is supplied to the photonic crystal; And a plurality of light output terminals provided on the other side of the crystal other than the incident side and selectively outputting the transmitted light.

More specifically, the optical switch of the present invention comprises:
An optical input terminal provided on the first side of the photonic crystal, the optical input terminal through which incident light is supplied to the photonic crystal, and at least two optical output terminals; A first light output terminal provided on the other side of the photonic crystal for outputting a first transmitted light transmitted through the photonic crystal; and a first light output terminal provided on the other side of the photonic crystal. Has a different direction and forms a desired angle with respect to the incident ray.
A second light output terminal for outputting a transmitted light beam.

It is a further object of the present invention to provide a method for deflecting a light beam incident on one side of a photonic crystal at a controlled angle to provide a transmitted light beam having a desired direction from the other side of the photonic crystal. Is to provide.

That is, the method comprises the steps of providing, on one side of the photonic crystal, an incident light beam having a wavelength other than the bandgap wavelength of the photonic crystal, and applying energy to the photonic crystal to apply it to the photonic crystal. Deflecting the incident light beam and providing a transmitted light beam at a desired angle to the incident light beam from the other side of the photonic crystal.

Further objects and advantages of the present invention will be more clearly understood on the basis of the following preferred embodiments of the invention with reference to the accompanying drawings.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A beam deflecting device and an optical switch according to the present invention will be described in detail based on the following preferred embodiments.

The light beam deflecting device of the present invention comprises, for example, as shown in FIG. 1, a photonic crystal 1 designed to have a photonic bandgap wavelength different from the wavelength of an incident light beam, A deflection control means 4 for applying energy to the crystal to deflect a light beam incident on one side of the photonic crystal and providing a transmitted light beam at a desired angle to the incident light beam 5 from the other side of the photonic crystal. And

Photonic crystal 1 used in the present invention
Is a multidimensional periodic structure in which at least two types of materials having different dielectric constants are periodically arranged at intervals of about the wavelength of light. In other words, the photonic crystal 1 is made of at least two kinds of substances having different refractive indexes, and these substances are arranged so as to have a period of about half the wavelength of the light incident on the photonic crystal, The photonic band structure is an artificial periodic or quasi-periodic structure in which the angle of transmitted light with respect to incident light is determined.

In the light beam deflecting device of the present invention, for example, a photonic crystal 1 shown in FIG. 2A can be used. This photonic crystal 1 is a two-dimensional periodic structure in which cylindrical bodies 1d made of a first material are arranged at a predetermined period. In this case, the space between the adjacent cylinders 1d is filled with a second material having a different dielectric constant from the first material. The second material may be air. On the other hand, the photonic crystal 1 shown in FIG. 2B may be used. This photonic crystal has substantially the same structure as that of FIG. 2A except that the second material is a solid material and the first material is air. That is, the photonic crystal of FIG.
It is composed of a rectangular parallelepiped made of the second material, and a plurality of cylindrical voids 1e provided in the rectangular parallelepiped at a predetermined period.

Further, the photonic crystal 1 shown in FIG. 2C can be used. This photonic crystal
This is a three-dimensional periodic structure obtained by arranging fine spheres 1c made of the first material three-dimensionally at a predetermined period.
This structure is also called an artificial opal structure. In this case, the second material having a different dielectric constant from the first material is filled between the adjacent spheres 1c. The second material may be air. On the other hand, the photonic crystal 1 shown in FIG. 2D may be used. The photonic crystal 1 has substantially the same structure as that of FIG. 2C except that the second material is a solid material and the first material is air. That is, FIG.
The photonic crystal of (d) comprises a cube made of the second material and a plurality of spherical voids 1 provided at a predetermined period in the cube.
h. This structure is also called an inverted opal structure.

Further, a photonic crystal 1 shown in FIG. 2E can be used. The photonic crystal includes a substrate (for example, a silicon substrate) 10 having a honeycomb surface in which hexagonal concave portions (not shown) are periodically formed at predetermined intervals, and a predetermined number of thin films laminated on the honeycomb surface. And an artificial laminated structure consisting of Each of the thin films is a lower layer 1a made of a first material (for example, amorphous Si).
And an upper layer 1b made of a second material (for example, SiO ₂ ). Thus, a two-dimensional periodic structure of hexagonal concave portions is provided on the honeycomb surface of the substrate 10, and a periodic structure is provided in the height direction of the substrate 10 by a staggered arrangement of the lower layer 1 a and the upper layer 1 b. To form a three-dimensional periodic structure as a whole.

The photonic crystal for a light beam deflecting device of the present invention is not limited to the above-described photonic crystal. A conventionally known photonic crystal having another structure or a photonic crystal having a novel structure can be used in the light beam deflecting device of the present invention.

The photonic crystal 1 used in the light beam deflecting device of the present invention has a wavelength of a light beam incident on the photonic crystal (= incident light beam 5) different from the photonic band gap wavelength of the photonic crystal. Designed.
Therefore, if the wavelength of the incident light beam to be used is determined in advance, the material and structure of the photonic crystal are designed to have a photonic band gap wavelength different from that wavelength. Conversely, if the material or structure of the photonic crystal is determined in advance, a light having a wavelength different from the photonic band gap wavelength of the photonic crystal is used as the incident light. Even if a light beam having a photonic band gap wavelength is incident on the surface of the photonic crystal, transmitted light cannot be obtained from the other surface of the photonic crystal. In other words, incident light having a wavelength equal to the photonic bandgap wavelength is reflected at the surface of the photonic crystal and cannot pass through the photonic crystal. Therefore, if a light beam having a wavelength different from the photonic band gap wavelength is incident on the photonic crystal, transmitted light can be obtained from the photonic crystal.

By the way, as an optical characteristic inherent to the photonic crystal, if the wavelength of the light beam incident on the photonic crystal changes by only 1%, the refraction angle of the light beam incident on the photonic crystal increases by about 50 degrees. It has been known. This phenomenon was discovered in 1999 and is called the super prism effect. This phenomenon is caused by a large change in the shape of the photonic dispersion surface caused by a minute change in the wavelength of the incident light. That is, if the wavelength is changed by about 1%, the incident light passes through different dispersion planes, resulting in a large deflection of the incident light. However,
When a photonic crystal is used in an optical device such as an optical switch, it becomes necessary to refract incident light having a specific wavelength at a desired angle to provide output light (ie, transmitted light). . The present invention addresses this need with deflection control means, described in more detail below.

As mentioned above, the present invention provides a photonic crystal with an incident light beam having a wavelength other than its photonic bandgap wavelength so that the incident light beam can be reflected from the photonic crystal without reflecting the incident light beam from the photonic crystal. It is assumed that the light passes through the nick crystal. On this premise, a feature of the present invention is that an incident light beam incident on one side of the photonic crystal is deflected by applying energy to the photonic crystal, and a transmitted light beam that forms a desired angle with respect to the incident light beam is photo-crystallized. The nick crystal is provided from the other side.

Hereinafter, preferred embodiments of the deflection control means of the present invention will be described in detail.

The deflection control means 4 of the present invention changes the photonic band structure by applying energy to the photonic crystal 1 to change the optical path (or deflection angle) of the light beam incident on the photonic crystal. . In the case where an incident light beam having a specific wavelength is provided to one side of the photonic crystal without operating the deflection control means 4, the incident light is incident along an optical path A shown by a solid line in FIGS. 3 (a) and 4 (a). The light beam 5 propagates, and the transmitted light is output from the first position on the opposite side of the photonic crystal. In this case, the incident light does not propagate along the optical path B indicated by the dotted line. Next, when the deflection control means 4 is operated to change the photonic band structure of the photonic crystal, FIG.
In (b), the incident light propagates along the optical path B shown by the solid line, and the transmitted light is output from the second position on the opposite side of the photonic crystal. In this case, the incident light does not propagate along the optical path A indicated by the dotted line.

In other words, when the wavelength of the light beam propagating in the photonic crystal has a certain specified wavelength, the light beam travels in the direction of the potential gradient on the photonic dispersion surface.
Therefore, if the period of the periodic structure of the photonic crystal 1 or the refractive index ratio of the two substances constituting the photonic crystal 1 is changed by the deflection control means, the photonic dispersion plane changes and the inside of the photonic crystal changes. The propagating light beam is deflected.

When the photonic crystal 1 is made of at least two materials having different refractive indexes, the deflection control means changes the refractive index ratio between the materials by applying energy to the photonic crystal, thereby changing the refractive index ratio between the materials. A transmitted beam at a desired angle to the incident beam is provided from the photonic crystal. When at least one of the materials is an electro-optic material, the deflection control unit 4 preferably applies an electric field (including an electric field due to light) to the photonic crystal as energy.

For example, as shown in FIGS. 1 (a) and 1 (b), the deflection control means 4 comprises a pair of plate electrodes 50 arranged on both sides of the photonic crystal 1 and a voltage between the electrodes. And a voltage controller (not shown). In the figure, reference numeral 41 denotes a support for supporting the photonic crystal 1 and the electrode 50. The electrode 50 and the support 41 are preferably made of a material transparent to the incident light 5.

The electro-optic material used for the photonic crystal 1 includes a Pockels effect in which the refractive index changes in proportion to the electric field intensity, and an optical Kerr effect in which the refractive index changes in proportion to the square of the electric field intensity ( A material having a nonlinear optical effect such as a third-order nonlinear optical effect) can be used. For example, the Pockels coefficient is 1 × 10 ^{−12 to} 1000 × 10 ⁻¹²
It is desirable to use a material of m / V, and such electro-optical materials as KH ₂ PO ₄ , KDS ₂ PO ₄ , NH ₄ H ₂
PO ₄ , RbH ₂ PO ₄ , CsD ₂ AsO ₄ (DCDA),
BaTiO ₃ , Ba _1-x Sr _x TiO ₃ , KNbO ₃ , Li
NbO ₃ , KTiOPO ₄ (KTP), KTiOAsO ₄
(KTA), Pb _x La _1-x (Ti _y Zr _1-y ) O ₃ (PL
ZT).

According to the deflection control means 4 described above, the electrode 5
An electric field is applied to the photonic crystal 1 by applying a voltage between zero. The applied electric field is the photonic crystal 1
Is changed, and as a result, the photonic band structure of the photonic crystal is changed. The deflection control means 4 of the present embodiment can change the refractive index ratio by about 0.1 to 1%.

As described above, the deflection control device 4 of the present embodiment changes the refractive index ratio of the photonic crystal 1 by controlling the electric field applied to the photonic crystal 1. This change in the refractive index ratio results in a change in the photonic dispersion surface, and as a result, the deflection angle of the incident light 5 can be controlled. As described above, since the deflection angle is controlled by adjusting the voltage applied between the electrodes 50, the response speed of the light beam deflecting device can be increased. Further, the deflection control means of the present embodiment does not apply a mechanical stress to the photonic crystal 1, and thus has an advantage that the reliability of the device can be easily maintained for a long period of time.

As another embodiment of the deflection control means of the present invention, when at least one of the materials constituting the photonic crystal 1 is an acousto-optic material, the deflection control means 4 applies ultrasonic waves to the photonic crystal as energy. Is preferred.

As shown in FIG. 5, the deflection control means 4
Is provided with an ultrasonic wave applying means 52 for applying an ultrasonic wave to the photonic crystal 1. For example, the ultrasonic wave applying means 5
Reference numeral 2 includes a transducer using an ultrasonic transducer (for example, a piezoelectric element) and a power supply (not shown) for supplying a drive voltage to the transducer. The acousto-optic material is made of HgS, Tl ₃ AsS ₄ , Ge, Te, ZnT according to the wavelength of the light beam incident on the photonic crystal 1.
e, a material such as Pb ₅ Ge ₃ O ₁₁ . The deflection control means of the present embodiment can change the refractive index ratio by about 0.1 to 1%.

According to the above-described deflection control means, the ultrasonic wave applied to the photonic crystal 1 induces a periodic change in the refractive index of the photonic crystal, and as a result, photons (photons) due to phonons. Scattering (Brillouin scattering)
Causes the light to be diffracted. That is, when the refractive index ratio is changed by applying ultrasonic waves, the photonic band structure is changed as a result. By adjusting the frequency of the ultrasonic wave, the deflection angle of the light beam incident on the photonic crystal is controlled, so that a light beam deflecting device that responds to a relatively high frequency can be provided. Further, the deflection control means of the present embodiment does not apply a mechanical stress to the photonic crystal 1, and thus has an advantage that the reliability of the device can be easily maintained for a long period of time.

As another embodiment of the deflection control means of the present invention, the deflection control means 4 includes an external force applying means for applying an external force as energy to the photonic crystal 1 in order to obtain a dimensional change of the photonic crystal 1. It may be.
For example, the external force applying means includes a piezoelectric material disposed adjacent to the photonic crystal. In this case, since the dimensions of the photonic crystal can be directly and uniformly changed by using the piezoelectric material, the operation reliability of the light beam deflecting device can be improved.

For example, as shown in FIG. 6A, when the deflection control means 4 is not operated, the photonic crystal has dimensions H1 and H2. At this time, a light beam incident on one side of the photonic crystal propagates along the optical path A in the photonic crystal and is output from the first position on the other side of the photonic crystal. On the other hand, as shown in FIG. 6B, when the deflection control means 4 is operated, the photonic crystal size H
1, H2 changes to dimensions H1 '(> H1) and H2'(> H2), respectively. This dimensional change of the photonic crystal changes the photonic band structure, and consequently changes the ratio of the refractive index of the material constituting the photonic crystal. Therefore, the light beam incident on one side of the photonic crystal propagates along the optical path B in the photonic crystal and is output from the second position on the other side of the photonic crystal.

For example, the deflection control device 4 of the present embodiment
As shown in FIG. 7, a piezoelectric material 42 disposed on one side of the photonic crystal, a pair of electrodes 43a and 43b disposed on both surfaces of the piezoelectric material, a power supply for supplying a voltage between the electrodes, and a voltage controller (Not shown)
An electrode 43a is arranged between the piezoelectric material 42 and the photonic crystal 1. In the figure, reference numeral 41 denotes a support for housing the photonic crystal 1 and the piezoelectric material 42 therein. Piezoelectric material 42, electrodes 43a and 43b, and support 4
1 is preferably formed of a material transparent to the incident light 5.

As the piezoelectric material 42 (piezo material), for example, PZT such as Pb (Zr _0.52 , Ti _0.48 ) O ₃
Ceramics can be used. In addition, this PZT ceramic is from −400 × 10 ^{−12 to} 1000 × 10 ^−12.
It preferably has a piezoelectric constant of m / V. As an example, when a PZT ceramic having a thickness of 10 mm is used as a piezoelectric material and a voltage is applied between the electrodes 43a and 43b to apply an electric field of 1000 V / mm to the piezoelectric material 42, the thickness of the piezoelectric material 42 changes by about 5 μm. . Here, if the thickness of the photonic crystal 1 is 5 mm, the thickness dimension (H) changes by about 0.1%. This is enough to change the period of the photonic crystal 1.

In the deflection control means 4 described above, the dimension of the photonic crystal 1 (= period of the photonic crystal 1) is changed by using expansion and contraction of the piezoelectric element 42 in the thickness direction. The amount of expansion and contraction of the piezoelectric material 42 in the thickness direction can be controlled by a voltage controller. That is,
When a light beam having a predetermined wavelength is incident on the photonic crystal without applying a voltage between the electrodes 43a and 43b, the light beam passes through the photonic crystal 1 along the first optical path indicated by the solid arrow A in FIG. To Penetrate. On the other hand, when a voltage is applied between the electrodes 43a and 43b, the piezoelectric material 42 exerts a compressive stress on the photonic crystal 1 as shown by a plurality of arrows C in FIG. 7, thereby changing the photonic band structure. . As a result, the light beam incident on the photonic crystal is deflected and transmitted through the photonic crystal along the second optical path indicated by the dashed arrow B in FIG.

In other words, when the light beam incident on the photonic crystal 1 has a specified wavelength, the light beam is directed along the direction of the potential gradient of the energy dispersive surface, which is the equal energy surface of the band in the wavenumber space of the photonic crystal 1. To propagate. That is, light propagating through the photonic crystal travels in a direction crossing the energy dispersion plane. In this embodiment,
The change in the period of the photonic crystal 1 is obtained by changing the size of the photonic crystal, and as a result, the energy dispersion surface changes (contracts), and the incident light 5 is deflected.

As described above, according to the deflection control means 4 in this embodiment, the deflection angle of the light beam incident on the photonic crystal can be controlled by adjusting the dimensional change of the photonic crystal 1. Further, by driving the piezoelectric material 42, the period of the photonic crystal can be changed at a high speed, so that it is possible to provide a light beam deflecting device having a high-speed response. Furthermore, since a conventionally known piezoelectric element can be used for the deflection control means, there is an advantage that the cost performance of the light beam deflecting device can be improved.

Hereinafter, a modified example of the deflection control means using the piezoelectric material of the present invention will be introduced.

As shown in FIG. 8, the deflection control means 4 comprises a substrate 47 made of a piezoelectric material on which the photonic crystal 1 is formed, and a pair of electrodes 48a and 48b arranged on both sides of the substrate. Is provided. In this case, the piezoelectric substrate 4
Photonic crystal 1 by expansion and contraction in the thickness direction of 7
Resulting in a dimensional change of Compared to the case where a piezoelectric element is provided separately from the substrate supporting the photonic crystal 1, the deflection control means 4 of the present embodiment has a more sophisticated structure and exhibits excellent cost performance.
Preferably, the substrate 47 and the electrodes 48a, 48b are made of a material transparent to the incident light 5.

As an example, a square PZT ceramic substrate 47 of 5 mm × 5 mm is used, and electrodes 48 a and 48 are used.
2,000 V / m through this PZT ceramic substrate
When an electric field of m is applied, the thickness dimension of the PZT ceramic substrate 47 changes by about 5 μm. At this time, the size of the photonic crystal 1 changes by about 0.1%. This is enough to change the period of the photonic crystal 1. Note that the deflection control means 4 of the present embodiment can be operated by the same method as the deflection control means of FIG.

As a deflection control means according to another embodiment of the present invention, the external force applying means preferably includes a pair of electromagnets arranged on both sides of the photonic crystal. In this case, a mechanical stress is applied to the photonic crystal by an attractive force generated between the electromagnets.

For example, as shown in FIG. 9, the control means of this embodiment includes a pair of electromagnets 46a and 46b arranged on both sides of the photonic crystal, and a power supply (see FIG. 9) for supplying current to the coils of the electromagnets. (Not shown) and a current controller (not shown). In this case, the size of the photonic crystal is changed by an attractive force generated by energizing the electromagnet. Therefore, the deflection angle of the incident light beam can be controlled by adjusting the magnitude of the attraction force of the electromagnet.

According to the deflection control means 4, the distance between the electromagnets is reduced by exciting the electromagnets 46a and 46b, so that the photonic crystal 1 receives compressive stress. This compressive stress causes a dimensional change in the photonic crystal 1, and as a result, the period of the photonic crystal 1 changes. That is, when a light beam having a predetermined wavelength is incident on the photonic crystal without exciting the electromagnets 46a and 46b, the light beam passes through the photonic crystal along the first optical path indicated by the solid arrow A in FIG. On the other hand, when the electromagnet is excited, the electromagnet provides a compressive stress to the photonic crystal 1 and consequently the light rays incident on the photonic crystal are deflected and along the second optical path indicated by the dashed arrow B in FIG. Transmit through photonic crystals.

As described above, in this embodiment, the electromagnet 46
Since the dimensional change of the photonic crystal 1 is controlled by adjusting the amount of current supplied to the a and 46b to provide a desired deflection angle of the light beam incident on the photonic crystal, a small-sized light beam deflecting device having a high-speed response is provided. Can be realized.

As still another embodiment of the present invention, the deflection control means 4 includes a heating means for heating the photonic crystal and a temperature changing means for generating a thermal stress in the photonic crystal. It is preferable to include heating control means.

For example, as shown in FIG. 10, the deflection control means 4 comprises a pair of heaters 49 arranged on both sides of the photonic crystal 1, a power supply for supplying a current to these heaters, a current controller (Not shown). Note that the heater 49 is preferably formed of a material that is transparent to the incident light 5.

In the present embodiment, the two materials constituting the photonic crystal 1 are preferably materials having a relatively large linear expansion coefficient. For example, as these materials, polyethylene (linear expansion coefficient: 100 × 10 ^{−6 to} 20)
0 × 10 ⁻⁶ / K) and acrylic (linear expansion coefficient: 80 × 10
⁻⁶ / K). In this case, the heater 4
Applying a current to 9 causes a thermal expansion of the photonic crystal 1, resulting in a dimensional change of the photonic crystal. Therefore, by adjusting the amount of current supplied to the heater, the deflection angle of the incident light beam in the photonic crystal can be controlled. As described above, in the present embodiment, the dimensions of the photonic crystal are directly changed by the thermal expansion of the photonic crystal itself instead of externally applying a mechanical force to the photonic crystal.

For example, in order to deflect a light beam incident on the photonic crystal 1, the size of the photonic crystal 1 is set to 0.
If it is necessary to change the temperature by 1 to 1%, it is preferable to increase the temperature of the photonic crystal 1 by about 12.5 to 125 K by the heater 49. The thermal expansion of the resulting photonic crystal changes its photonic band structure.

As a modified example, an external force applying member made of a material having a high coefficient of thermal expansion arranged so as to be in contact with the photonic crystal, a heater for heating the external force applying member, and supplying a current to the heater And the current controller may constitute the deflection control means. In this case, the thermal expansion of the heated external force applying member causes an increase in the volume of the external force applying member, and as a result, the size of the photonic crystal can be changed. Therefore, by adjusting the heating temperature of the external force applying member, the deflection angle of the light beam incident on the photonic crystal can be controlled.

As still another preferred embodiment of the deflection control means 4 of the present invention, an external force applying means as shown in FIG. 11 may be used. That is, the external force applying means is provided on the pressing plate 4 which is arranged to be in contact with the photonic crystal 1.
4, a driving means 45 for moving the pressing plate 44 toward the photonic crystal to provide a compressive stress to the photonic crystal, and a support in which the photonic crystal 1, the pressing plate 44 and the driving means 45 are housed. 41.
In this case, the dimensions of the photonic crystal 1 are changed by the movement of the pressing plate 44 toward the photonic crystal. As the driving unit 45, a known pressurizing unit such as a piston controlled by air pressure, water pressure, hydraulic pressure, or the like can be used. Further, it is preferable that the pressing plate 44, the driving means 45, and the support 41 be formed of a material transparent to the incident light 5.

In the above-mentioned deflection control means 4, when a light beam of a predetermined wavelength is made incident on the photonic crystal without operating the driving means 45, the light beam travels along the first optical path indicated by the solid arrow A in FIG. Transmit through the nick crystal.
On the other hand, when the driving means 45 is operated, as shown by a plurality of arrows C in FIG. 11, the pressing plate 44 applies a compressive stress to the photonic crystal 1 to change the photonic band structure. As a result, the light beam incident on the photonic crystal is deflected and passes through the photonic crystal along the second optical path indicated by the dashed arrow B in FIG. Therefore, the deflection angle of the light beam incident on the photonic crystal can be controlled by adjusting the amount of movement of the pressing plate 44 or the magnitude of the external force applied to the photonic crystal 1 via the pressing plate 44. .

As another preferred embodiment of the deflection control means of the present invention, when the photonic crystal contains a semiconductor material such as Si or GaAs, the deflection control means injects carriers into the photonic crystal to reduce the refractive index. Preferably, it is changed.

For example, as shown in FIG. 12, the deflection control means 4 includes an electric circuit 60 for injecting carriers such as electrons into the photonic crystal. In this case, the photonic band structure of the photonic crystal changes according to the amount of carriers injected into the photonic crystal. Therefore, if the amount of current flowing through the electric circuit 60, that is, the amount of carrier injected into the photonic crystal 1, is adjusted, the deflection angle of a light beam incident on the photonic crystal can be controlled.

In this embodiment, since elements commonly used in integrated circuits, such as Si and Ge, are used as a constituent material of the photonic crystal, an existing semiconductor device is used for manufacturing a light beam deflecting device using the photonic crystal. There is an advantage that the production line can be used and the integration becomes easy. Further, it becomes possible to realize a light beam deflecting device having a high switching speed on the order of ns to ps.

As still another embodiment of the deflection control means of the present invention, when the photonic crystal includes a photorefractive material, the deflection control means may irradiate the photonic crystal with light to change the refractive index. preferable.

For example, as shown in FIG. 13, the deflection control means 4 includes a light irradiation means (not shown) for irradiating the photonic crystal 1 with light. In this case, the photonic band structure of the photonic crystal changes according to the amount of light applied to the photonic crystal. Therefore,
By adjusting the amount of irradiation, the deflection angle of the light beam incident on the photonic crystal can be controlled. Light irradiation
The photonic crystal 1 may be irradiated from above or from the side. Alternatively, light (arrow C) may be applied to the photonic crystal via a waveguide 62 provided adjacent to the photonic crystal. The light beam deflecting device of the present embodiment has ns to
In addition to providing switching speed on the order of ps,
It can also support all-optical packet-switched networks.

In each of the various deflection control means 4 described above, the photonic crystal 1 is, as shown in FIG. 14, a linear distance between the incident position where the light beam enters and the emission position where the transmitted light beam is provided. Is preferably shaped to provide at least two optical paths that are substantially the same.
By keeping the length of the optical path constant, a phase shift can be prevented. In FIG. 14, corners of the photonic crystal are removed so that the optical path indicated by the two arrows has a certain length. Further, as the deflection control means 4, the photonic crystal 1 is irradiated with light (arrow C) via the waveguide 62 by the light irradiation means described above.

It is particularly preferable to use the above-described light beam deflecting device of the present invention for an optical switch. That is, the optical switch is provided with the light beam deflecting device of the present invention, an optical input terminal through which a light beam is supplied to the photonic crystal, and the light input terminal of the photonic crystal. And a plurality of light output terminals for selectively outputting transmitted light.

FIG. 15 shows an example of the optical switch of the present invention. On the input side of the optical switch, there is a single optical input terminal 2 such as a rod lens that makes a light beam provided from the optical fiber 12 enter one side of the photonic crystal 1, and on the output side of the optical switch, There are three light output terminals 3a, 3b, 3c, such as rod lenses, each providing transmitted light from the other end of the photonic crystal 1 to the corresponding optical fiber 13a, 13b, 13c. The deflection control means 4 is arranged at the upper and lower ends of the photonic crystal 1.

This optical switch controls the photonic band structure of the photonic crystal 1 to selectively provide an optical output signal from one of a plurality of optical paths in the photonic crystal on which a single optical input signal is incident. Is what you do. That is, in the case of FIG. 15A, as indicated by the arrow,
The transmitted light is transmitted to the corresponding optical fiber 13 via the output terminal 3a.
output to a. Therefore, the remaining output terminals 3b, 3
No transmitted light is output from c. Similarly, FIG.
In the case of, as shown by the arrow, the transmitted light is
The signal is output to the corresponding optical fiber 13c via the line c. Therefore, no transmitted light is output from the remaining output terminals 3a and 3b. Further, in the case of FIG. 15C, the transmitted light is output to the corresponding optical fiber 13b via the output terminal 3b, as indicated by the arrow. Therefore, no transmitted light is output from the remaining output terminals 3a and 3c. As a modification of the present embodiment, the number of optical output terminals may be two, or three or more.

As described above, in the optical switch according to the present invention, it is possible to switch a plurality of optical paths at different angles with respect to the incident light in the photonic crystal. Further, the size of the optical switch can be reduced while realizing a relatively large deflection angle as compared with a conventional optical switch using a waveguide. Further, there is an effect that crosstalk of optical signals can be prevented and high transmission efficiency can be secured.

FIG. 1 shows another embodiment of the optical switch of the present invention.
6 is shown. The optical switch of FIG. 15 uses one photonic crystal 1 and selectively provides an output signal from one of a plurality of optical paths in the photonic crystal on which a light beam enters. On the other hand, the optical switch of the present embodiment uses the matrix arrangement of the photonic crystals 1 and provides a plurality of optical output signals from a plurality of optical input signals at the same time.

That is, as shown in FIG. 16, this optical switch is provided with a matrix array in which a plurality of the above-described light beam deflecting devices are arrayed, and a plurality of external light beams provided on one side of the matrix array. And a plurality of light output terminals (not shown) provided on the other side of the matrix array. These photonic crystals 1 have a single substrate 1
It is formed on 0 '. In FIG. 16, the number of photonic crystals 1 used in the matrix arrangement is 16 (=
4x4), with four input terminals and four output terminals on each side of the matrix arrangement. The number of photonic crystals, the number of input terminals, and the number of output terminals
It can be determined appropriately.

According to the optical switch of the present embodiment, the deflection angle of the light beam incident on the photonic crystal of each light beam deflecting device in the matrix array is controlled by the above-described deflection control means. By switching the optical paths, a plurality of different optical output signals can be provided simultaneously. Further, the reliability of the switch operation can be improved as compared with a conventional optical switch having a plurality of movable means for deflecting mirrors. Furthermore, since many photonic crystals 1 can be formed on a single substrate 10 ', the size of the optical switch can be significantly reduced.

[0070]

As can be understood from the preferred embodiment of the present invention described above, the deflection control means changes the photonic band structure to deflect a light beam (= incident light beam) incident on the photonic crystal. A compact light beam deflecting device that outputs a transmitted light beam having a relatively large angle with respect to an incident light beam can be provided. In addition, since a plurality of optical paths can be set for one incident light by adopting a plurality of different deflection angles, a photonic crystal that can prevent crosstalk of optical signals and secure high transmission efficiency can be provided. A new optical switch can be provided.

[Brief description of the drawings]

1 (a) and 1 (b) are a schematic sectional view and a schematic perspective view of a light beam deflecting device according to a preferred embodiment of the present invention.

FIGS. 2A to 2E are perspective views showing the structure of a photonic crystal that can be used in the light beam deflecting device of the present invention.

3 (a) and 3 (b) are perspective views showing optical paths in the photonic crystal of FIG. 2 (c).

FIGS. 4A and 4B are perspective views showing optical paths in the photonic crystal of FIG. 2E.

FIG. 5 is a schematic perspective view of a beam deflecting device using ultrasonic waves according to another preferred embodiment of the present invention.

FIGS. 6A and 6B are schematic perspective views showing the operation of a light beam deflecting device including an external force applying unit of the present invention.

FIG. 7 is a schematic cross-sectional view of a light beam deflecting device using a piezoelectric material according to another preferred embodiment of the present invention.

FIG. 8 is a schematic sectional view showing a modification of the light beam deflecting device of FIG. 7;

FIG. 9 is a schematic perspective view of a light beam deflecting device using an electromagnet according to another preferred embodiment of the present invention.

FIG. 10 is a schematic sectional view of a light beam deflecting device using a heating means according to another preferred embodiment of the present invention.

FIG. 11 is a schematic cross-sectional view of a light beam deflecting device using an external force applying unit according to another preferred embodiment of the present invention.

FIG. 12 is a schematic perspective view of a light beam deflecting device using carrier injection means according to another preferred embodiment of the present invention.

FIG. 13 is a schematic perspective view of a light beam deflecting device using light irradiation means according to another preferred embodiment of the present invention.

FIG. 14 is a schematic perspective view showing a preferred structure of a photonic crystal used in the light beam deflecting device of the present invention.

FIGS. 15A to 15C are schematic cross-sectional views showing the operation of an optical switch using the light beam deflecting device of the present invention.

FIG. 16 is a plan view of a matrix type optical switch using the light beam deflecting device of the present invention.

FIG. 17 is a schematic perspective view of a conventional optical switch using a photonic crystal. DESCRIPTION OF SYMBOLS 1 Photonic crystal 4 Deflection control means 5 Incident light 41 Support 50 Plate electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasufumi Masaki 1048 Kadoma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Inventor Katsumi Yoshino 166-3 Oiocho, Kishiwada-shi, Osaka F-term (reference) 2H041 AA14 AB38 AC01 AC02 AC04 AC07 AC08 2H047 KA03 RA08 2K002 AB06 BA06 BA11 BA12 BA13 CA03 CA05 CA13 DA01 DA20 HA01 HA03 HA10 HA11

Claims (17)

[Claims] 1. A photonic crystal designed to have a photonic bandgap wavelength different from a wavelength of an incident light beam, and energy is applied to the photonic crystal to be incident on an incident side of the photonic crystal. And a deflection control means for deflecting the light beam and providing a transmitted light beam having a desired angle to the light beam from a side other than the incident side of the photonic crystal. 2. The method according to claim 1, wherein the photonic crystal is made of at least two kinds of materials having different refractive indexes, and the control unit controls a ratio of the refractive indexes between the materials by applying the energy. The light beam deflecting device according to claim 1. 3. The light beam deflecting device according to claim 2, wherein at least one of the materials is an electro-optic material, and the control means applies an electric field to the photonic crystal as energy. 4. The light beam deflecting device according to claim 2, wherein at least one of said materials is an acousto-optic material, and said control means applies ultrasonic waves to said photonic crystal as energy. 5. The light beam deflecting device according to claim 1, wherein said photonic crystal includes a semiconductor material, and said control means changes a refractive index by injecting carriers into said photonic crystal. 6. The light beam deflecting device according to claim 1, wherein the photonic crystal includes a photorefractive material, and the control unit changes the refractive index by irradiating the photonic crystal with light. . 7. The light beam deflecting device according to claim 1, wherein said control means changes the size of the photonic crystal by applying said energy. 8. The light beam deflecting device according to claim 7, wherein said control means includes external force applying means for applying an external force as energy to said photonic crystal. 9. The light beam deflecting device according to claim 8, wherein said external force applying means includes a piezoelectric material disposed adjacent to the photonic crystal. 10. The external force applying means includes a pair of electromagnets disposed on both sides of the photonic crystal, and applies a mechanical stress to the photonic crystal by an attractive force generated between the electromagnets. Item 9. The light beam deflecting device according to Item 8. 11. The external force applying means includes a material having a high coefficient of thermal expansion arranged to be in contact with a photonic crystal, and a heating means for heating the material, wherein the material heated by the heating means is provided. 9. The beam deflecting device according to claim 8, wherein the external force is applied to the photonic crystal by thermal expansion of the photonic crystal. 12. The control means includes a heating means for heating the photonic crystal, and a heating control means for changing a temperature of the photonic crystal to generate a thermal stress in the photonic crystal. The light beam deflecting device according to claim 1, wherein 13. The photonic crystal is configured to provide at least two optical paths having substantially the same linear distance between an incident position where the light beam enters and an exit position where the transmitted light beam is provided. The light beam deflecting device according to claim 1, wherein: 14. An optical switch using the light beam deflecting device according to claim 1, which is provided on the incident side of a photonic crystal, and through which the light beam is supplied to the photonic crystal. An optical switch comprising: an optical input terminal; and a plurality of optical output terminals provided on a side other than the incident side of the photonic crystal and selectively outputting the transmitted light. 15. An optical switch using the light beam deflecting device according to claim 1, provided on the incident side of a photonic crystal, and the light beam is supplied to the photonic crystal via the light switch. An optical input terminal; and at least two optical output terminals, wherein the optical output terminal is provided on a side other than the incident side of the photonic crystal, and outputs a first transmitted light transmitted through the photonic crystal. A first light output terminal for transmitting light, and a second transmission having a direction different from that of the first transmitted light beam and forming a desired angle with respect to the light beam. An optical switch, comprising: a second optical output terminal for outputting a light beam. 16. A matrix array comprising a plurality of the light beam deflecting devices according to claim 1 arranged therein, and a plurality of light beam deflecting devices provided on one side of the matrix array for receiving a plurality of external light beams. An optical switch comprising: a plurality of optical input terminals; and a plurality of optical output terminals provided on the other side of the matrix array. 17. Providing an incident light beam having a wavelength other than the band gap wavelength of the photonic crystal on one side of the photonic crystal, and applying energy to the photonic crystal to make it incident on the photonic crystal. Deflecting the transmitted light beam and providing a transmitted light beam having a desired angle with respect to the incident light beam from the other surface of the photonic crystal.