JP2004145317A - Optical deflector, optical switch composed of the optical deflector, optical scanning device and method of deflecting light - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical deflector which has a compact configuration and is operated at high speed, an optical switch constituted of the optical deflector, an optical scanning device, and a method of deflecting light. <P>SOLUTION: The optical deflector has a photonic crystal part, a light introducing means which introduces light into the photonic crystal part, and an external force impressing means which deforms the photonic crystal part with an external mechanical force and varies the refraction angle of the light introduced by the light introducing means at the photonic crystal part. The device has a compact constitution and is operated at high speed. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an optical deflecting device, an optical switch constituted by the optical deflecting device, an optical scanning device, and an optical deflecting method.

In recent years, a new artificial crystal called “photonic crystal” in which substances having different refractive indices are periodically arranged at intervals of about a wavelength has been proposed (Non-Patent Document 1) and has attracted attention. This artificial crystal exhibits unique optical characteristics, such as the band gap of light and apparent refractive index anomalies caused by the so-called photonic band structure, similar to the band structure of semiconductors. Therefore, research and development as an optical element have been actively conducted.
One of the optical characteristics that attracts attention is a phenomenon called a super prism effect. This is a phenomenon caused by the above-mentioned apparent refractive index abnormality, and shows a refraction angle that is several to several hundred times that of a normal prism made of optical glass with respect to a change in wavelength or incident angle. .

As an application example of the above-described phenomenon, there has been proposed a method of controlling a deflection angle by changing the wavelength of laser light incident on a photonic crystal (see Patent Documents 1 and 2).
Further, there has been proposed a method of controlling the deflection angle by changing the angle of a photonic crystal using an actuator with respect to incident laser light (see Patent Documents 3 and 4).
JP 2001-13439 A U.S. Pat. No. 6,448,997 JP 2001-42248 A U.S. Patent Application Publication No. 2002027696 E. FIG. Yablonovitch, Phys. Rev .. Lett. , 58 (1987) 2059-2062.

However, in order to change the wavelength of laser light, it is necessary to use a wavelength tunable laser as a light source, but such a laser is generally expensive. Further, it is not suitable in principle for applications requiring a constant wavelength.
Further, when the angle of the photonic crystal is changed, there is a problem in that the mechanism for moving the entire crystal becomes large, and the operating frequency decreases.

In view of the above, the present invention has been made to solve the above-described problems, and has an optical deflecting device capable of high-speed operation with a compact configuration, an optical deflecting device including the optical deflecting device, an optical switch including the optical deflecting device, It is an object to provide an apparatus and a light deflection method.

The present invention provides an optical deflecting device, an optical switch, an optical scanning device, and an optical deflecting method constituted by the optical deflecting device configured as follows.
The light deflecting device of the present invention is a photonic crystal part, a light introducing means for introducing light into the photonic crystal part, and the photonic crystal part is deformed by a mechanical external force, and is introduced by the light introducing means. External force applying means for changing a refraction angle of the light in the photonic crystal portion.
Further, the present invention is an optical switch or an optical scanning device in which light deriving means for deriving light deflected in a desired light deriving direction by the light deflector is added to the light deflector.
Further, the light deflection method of the present invention is characterized in that light is introduced into a photonic crystal portion, and a mechanical external force is applied to the photonic crystal portion to deform the photonic crystal portion. Changing the refraction angle at the portion and deflecting the introduced light.
The refraction angle changes depending on the period of the photonic crystal. The refraction angle can also be changed by fixing the cycle and changing the refractive index distribution within one cycle.

According to the present invention, it is possible to realize an optical deflecting device capable of high-speed operation with a compact configuration, an optical switch, an optical scanning device, and an optical deflecting method configured by the optical deflecting device.

In the embodiment of the present invention, by applying the above configuration, for example, an actuator that applies a mechanical external force to a photonic crystal made of a deformable material is attached, and the Is used to deform the photonic crystal, whereby the laser light can be deflected by changing the refraction angle without modulating the wavelength of the laser light.
Further, by changing the emission position of the laser light transmitted through the photonic crystal by the above-described refraction angle, an optical switch that guides the laser light to a desired path can be realized.
Further, by changing the emission angle of the laser light transmitted through the photonic crystal by the above-described refraction angle, it is possible to realize an optical scanning device that scans the laser light at a desired angle.
Further, according to the present configuration in which the photonic crystal is directly deformed as described above, a high-speed operation can be realized with a compact configuration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Example 1]
In this embodiment, the refractive index is changed by applying a periodic force to the photonic crystal to cause mechanical deformation.
FIG. 1 is a diagram illustrating a device configuration of an optical switch according to a first embodiment of the present invention. As shown in FIG. 1, an actuator 101 made of a piezoelectric element and a photonic crystal 102 made of PMMA (polymethyl methacrylate) are connected and housed in a housing 103. The photonic crystal 102 is a plate-shaped PMMA 113 provided with a through hole 114, and the through hole is formed by X-ray lithography.

The operation direction of the actuator 101 is the direction of the arrow indicated by the expansion and contraction direction 112, and causes the photonic crystal 102 to expand and contract in the same direction. The housing 103 has three holes with the photonic crystal 102 interposed therebetween to secure an optical path. Each of the holes is provided with an optical fiber for introducing or extracting a laser beam. The first optical fiber 106 and the second optical fiber 106 are located opposite to the third optical fiber 108 with the photonic crystal 102 therebetween. 107 are arranged.
The control circuit 104 sends the control amount to the drive circuit 105 to drive the actuator 101.
The incident light 111 from the third optical fiber 108 passes through the photonic crystal 102 through the first optical path 109 or the second optical path 110 according to the control amount output from the control circuit 104, and is transmitted through the first optical fiber 102. The light enters the second optical fiber 107 or 106.

In the above description, the photonic crystal 102 was formed by forming the through-hole 114 in the continuous plate-shaped PMMA 113. The structure of the photonic crystal is not limited to this, and a periodic structure in which columnar members are vertically arranged on the substrate and arranged regularly may be formed. In this case, the actuator can apply a horizontal force to the substrate to expand and contract, thereby indirectly changing the periodicity of the columnar members. Further, if the substrate is formed of a piezoelectric material so that the substrate itself expands and contracts, an actuator and a housing are not required.

The material of the photonic crystal 102 is not limited to the above-described example, and may be appropriately selected from physical characteristics such as a refractive index and a Young's modulus, process compatibility at the time of fabrication, and compatibility with a use environment such as temperature and humidity. It is possible.
In the present embodiment, a piezoelectric element is used as the actuator 101, but other driving mechanisms such as a feed screw mechanism and a voice coil can be selected.

[Example 2]
In the present embodiment, the period of the photonic crystal is fixed, the refractive index is changed by changing the refractive index distribution within one period, and the change is made to occur continuously, thereby making the light deflection direction continuously variable. This realizes an optical scanner.
FIG. 2 is a diagram illustrating a device configuration of an optical scanner according to a second embodiment of the present invention. As shown in FIG. 2, an actuator 101 made of a piezoelectric element and a photonic crystal 102 are stacked and housed in a housing 103. As shown in FIG. 2, the photonic crystal 102 here is a parallel structure arranged in a direction perpendicular to the arrangement direction of the columnar members in which the deformable columnar independent members constituting the periodic structure 202 are arranged. It is formed so as to be sandwiched between two substrates 203.

動作 The operation direction of the actuator 101 is the direction of the normal to the surface of the substrate 203, and causes the photonic crystal 102 to expand and contract in the same direction. The housing 103 has two holes with the photonic crystal 102 interposed therebetween to secure an optical path. Laser light from the laser 204 enters the element through one hole, passes through the photonic crystal 102, and exits from the other hole that is widely opened in the scanning direction. The control circuit 104 calculates a control amount and sends it to the drive circuit 105 to drive the actuator 101 so that the laser beam deflected at a desired angle is emitted.

The photonic crystal 102 is manufactured, for example, as follows. First, in order to improve the transmittance of laser light, a multilayer film is formed on a substrate 203 made of Si by vapor deposition, and a reflective film 201 is formed. Next, PMMA (polymethyl methacrylate) is applied on the reflective film 201, and a periodic structure 202 is manufactured by X-ray lithography. The individual columnar members constituting the periodic structure 202 are isolated and form a two-dimensional periodic structure on the reflective film 201 in a plane parallel to the substrate 203 surface.
Next, another one in which the reflective film 201 is formed on the substrate 203 made of Si is prepared, and the reflective film 201 is overlapped on the periodic structure 202 made of PMMA. Further, the end face on the emission side is ground into an arc-shaped shape to obtain the shape shown in FIG. This drawing is viewed from the normal direction of the surface of the substrate 203.

外 By applying an external force to the photonic crystal 102 thus formed in a direction normal to the surface of the substrate 203, the individual columnar members constituting the periodic structure 102 are deformed. The drive circuit 105 is controlled by the control circuit 104 so as to apply a continuous voltage to the actuator. As a result, the actuator causes continuous expansion and contraction displacement, deforms the columnar member, and continuously changes the diameter of the columnar member, whereby the refraction angle can be controlled. Therefore, the incident light 111 that has entered the photonic crystal 102 from the laser 204 is refracted at an angle corresponding to the amount of deformation specified by the control circuit 104 and transmitted through the photonic crystal 102, and as shown in FIG. Numeral 301 scans in the angle range shown in the deflection range 302.

The materials of the reflective film 201, the periodic structure 202, the substrate 203, and the like are not limited to the above-described examples. It can be appropriately selected from the suitability and the like. In the present embodiment, a piezoelectric element is used as the actuator 101, but other driving mechanisms such as a feed screw mechanism and a voice coil can be selected.

FIG. 2 is a diagram illustrating a device configuration of the optical switch according to the first embodiment of the present invention. FIG. 6 is a diagram illustrating a device configuration of an optical scanner according to a second embodiment of the present invention. FIG. 4 is a diagram illustrating a configuration of an element according to a second embodiment of the present invention.

Explanation of reference numerals

101: Actuator 102: Photonic crystal 103: Housing 104: Control circuit 105: Drive circuit 106: First optical fiber 107: Second optical fiber 108: Third optical fiber 109: First optical path 110: Second optical path 111: incident light 112: expansion / contraction direction 113: plate-shaped PMMA
114: through hole 201: reflective film 202: periodic structure 203: substrate 204: laser 301: emitted light 302: deflection range

Claims (9)

A photonic crystal part,
Light introducing means for introducing light into the photonic crystal part,
An external force applying unit that deforms the photonic crystal unit by a mechanical external force and changes a refraction angle of the light introduced by the light introducing unit in the photonic crystal unit,
An optical deflecting device comprising: The photonic crystal unit is formed of a member that can be deformed by an external force, and the external force applying unit applies a mechanical external force to the photonic crystal unit from a direction of a period of a periodic structure of the photonic crystal unit, The optical deflector according to claim 1, further comprising a configuration for changing a refraction angle in the photonic crystal part. The external force applying means applies a mechanical external force to the photonic crystal unit in a direction perpendicular to the direction of the period of the periodic structure of the photonic crystal unit, and changes the refraction angle in the photonic crystal unit. The optical deflecting device according to claim 1, comprising: The photonic crystal section includes a deformable columnar independent member forming the periodic structure, and a pair of support members disposed in a direction perpendicular to an arrangement direction of the independent member with the independent member interposed therebetween. 4. The light deflecting device according to claim 3, wherein: The optical deflecting device according to claim 4, wherein the supporting member is formed by a substrate and a reflective layer provided on the substrate surface of the substrate on the side of the independent member. 2. The light deflecting device according to claim 1, wherein an end face on the emission side of the photonic crystal portion is formed in an arc shape. A light deflector according to any one of claims 1 to 6, and light deriving means for deriving light deflected in a desired light derivation direction by the light deflector. Light switch. に お い て An optical scanning device provided with an optical deflecting device, wherein the optical deflecting device is constituted by the optical deflecting device according to any one of claims 1 to 6. Light is introduced into the photonic crystal portion, and a mechanical external force is applied to the photonic crystal portion to deform the photonic crystal portion, thereby changing a refraction angle of the introduced light in the photonic crystal portion, A light deflecting method characterized by deflecting the introduced light.

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