JP2002258334A - Multichannel optical switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a very-fast multichannel optical switch which converts a serial signal light train with a high bit rate of >=1 Tbit/s into spatially separated parallel signal light trains. SOLUTION: A signal light which is made incident at an angle θ1 of incidence is reflected by the surface of a very-fast optical response film 14 and projected from a light projection part 18B of a right-angled prism 10. The optical response film 14 when irradiated with a control light varies in refractive index and absorptivity and then varies in reflection factor to a signal light to function as a fast optical switch. This optical switch can convert a serial signal light train into spatially separated parallel signal light trains by irradiating the optical response film 14 with the control signal when signal lights having a specific beam diameter are made incident from the right-angled prism 10 at specific intervals and beam parts which are different at right angles to the incidence direction in incidence surfaces of the respective incident signal lights are reflected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multi-channel optical switch that can be used as an optical distribution device (optical demultiplexer) in an optical communication system or the like.

[0002]

2. Description of the Related Art In recent years, with the development of information communication networks such as the Internet, the capacity required for communication trunks is increasing dramatically. Tb corresponding to increasing information volume
In order to realize an ultra-high-speed optical communication network on the order of it / s (terabit / second, Tbps), a time division multiplexing method, a wavelength multiplexing method, etc., which can transmit more information with one optical fiber, are used. Are being considered.

In an optical communication system of the time division multiplex system,
On the transmitting side, the multi-channel signal light is multiplexed into time-serial signal light and transmitted to one optical fiber transmission line, and on the receiving side, the multiplexed serial signal light is converted into a multi-channel signal light. It is distributed to light, and optical multiplexing (optical multiplex) corresponding to this system
Methods and apparatuses for optical distribution (optical demultiplexing) are being studied.

Conventionally, since it is difficult to electrically control a terabit signal, various types of optical switches have been studied in order to control a terabit signal with light. As a method of distributing the multiplexed serial signal light to multi-channel signal light, “O plus E No.
187 (June 1995), page 73 and below, a phase shift method that changes the phase of signal light and a frequency shift method that changes the frequency (wavelength) of signal light are considered. .

A typical phase shift method uses a two-path interferometer utilizing the optical Kerr effect. The refractive index of a nonlinear optical medium inserted into one of the two paths of the two-path interferometer is calculated as follows.
When the control light pulse is not input by changing the control light (gate light) synchronized with the multiplexed serial signal light, the signal light pulse at that time is output from one output port of the two-path interferometer, and the control is performed. When an optical pulse is input, the signal light pulse at that time is output from the other output port of the two-path interferometer.

In the frequency shift method, the frequency (wavelength) of multiplexed serial signal light is changed for each channel by a control light in a nonlinear optical medium, and the changed signal light is changed by a wavelength separation element to each channel. The signal light is spatially separated.

On the other hand, Japanese Patent Application Laid-Open No. 11-15031 discloses a large-area light distribution using a light-responsive material in which the transmittance of signal light increases only during irradiation with control light and the light is turned on. An optical switch is described. This optical switch has a characteristic that a 1 Gbps serial signal can be collectively converted into a plurality of parallel signals.

As an element for changing the light reflectance, an ATR-FP type element in which a metal film 12 and an ultra-high-speed photoresponsive film 14 are formed on the bottom surface of a right-angle prism 10 as shown in FIG. 1 is known. (A.Yacoubian and T.Aye, "Enhan
ced optical modulation usingazo-dye polymers ", App
lied Optics Vol.32, No.17, 1993, pp.3073-3080.).
In this ATR-FP type device, the thickness d _{2 of the} metal film 12 is
Is larger than the wavelength of light and is sufficiently thick, the signal light incident on the metal film 12 from the right-angle prism 10 side is totally reflected, but if the metal film 12 is thin, part of the signal light
And propagates in the ultrafast photoresponsive film 14. When the specific incident angle and the specific thickness of the ultrafast photoresponsive film 14 are set, the reflectance of the incident signal light decreases, so that a standing wave in the thickness direction is generated in the ultrafast photoresponsive film 14. It is considered that the reflectivity of the signal light decreases.

In this ATR-FP type device, when an azo dye is used as a photoresponsive material, when the azo dye is irradiated with control light, the refractive index of the azo dye changes. The reflectivity of the signal light changes, and it operates as an optical switch. Further, when a photochromic material is used as the light-responsive material, the reflectance of the signal light changes as a result of the change in the absorptance of the photochromic material by irradiating the control light, thereby operating as an optical switch (T. Nagamura and K. Sasaki, "
All-optical parallel switching by the use of guid
ed wave geometry composed of a thin Ag film and a
polymer thin film containing organicdye ", SPIE Pro
ceedings Vol. 3466, No., 1998, pp. 212-221.).

[0010]

However, the above-described phase shift method spatially separates a signal light pulse that coincides with the control light pulse temporally from a signal light pulse that does not coincide with the control light pulse in time. In order to obtain only two outputs and separate and obtain multi-channel signal light pulses, the above-described two-path interferometer is multi-stage (where N is the number of channels, (N
-1) The signal light and the control light must be changed in their directions with respect to the two-path interferometer of each stage, and one of them must be incident with a different time delay,
The optics become significantly more complex, the more channels there are, the more difficult it is to deal with, and the very advanced process technology required to have a precise time difference between the signal light or control light of each stage. .

In the frequency shift method described above, the output light of a plurality of channels can be collectively obtained by converting the signal light into a different frequency (wavelength) for each channel at once in the nonlinear optical medium. In addition, as the number of channels increases, it becomes difficult to convert the signal light to a different frequency for each channel at a time, and thus there is a problem similar to the above-described phase shift method.

Further, the conventional light-responsive material has a low response speed, and an ATR-FP type element which can be used as a high-speed optical switch for controlling a terabit signal has not been obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to convert a serial signal light train having a high bit rate of 1 Tbit / s or more into a parallel separated parallel light beam. It is an object of the present invention to provide an ultra-high-speed multi-channel optical switch for converting a signal into an optical signal train.

[0014]

In order to achieve the above object, a multi-channel optical switch according to the present invention is provided with a light incident portion, a light emitting portion, and an optical switch provided between the light incident portion and the light emitting portion. A light-transmitting member having a surface that intersects the optical path of the incident light from the incident portion, a metal film formed on the surface of the light-transmitting member, and a control light that is laminated on the metal film and irradiated with control light. An ultra-high-speed light-responsive film that changes a refractive index and an absorptance for signal light by reflecting signal light incident from the light incident portion toward the light emitting portion when the control light is irradiated. A light reflecting portion for changing the reflectance to be reflected, a serial light signal composed of signal light having a predetermined beam shape, and a signal light incidence means for entering from the light incidence portion; Different beam parts in the direction perpendicular to the Is when the, characterized by being configured to include a control light irradiating means for irradiating a control light to the ultrafast photoresponsive film.

In the present application, the ultra-high-speed photoresponsive film is
Recovery time constant is 5 ps (picoseconds) or less (1 ps = 10 ^-12
This is a membrane that responds in s). Further, as the light transmitting member, for example, a prism can be used.

The multi-channel optical switch of the present invention includes a light incident portion, a light emitting portion, and a surface provided between the light incident portion and the light emitting portion and intersecting an optical path of incident light from the light incident portion. Light transmitting member. A metal film is formed on a surface of the light transmitting member that is provided between the light incident portion and the light emitting portion and intersects the optical path of the incident light from the light incident portion, and control light is formed on the metal film. An ultra-high-speed photoresponsive film whose refractive index and absorptivity for signal light changes by being irradiated is laminated, and the signal light incident from the light incident part when the control light is irradiated is directed toward the light emitting part. A light reflecting portion that changes the reflectance of reflection is configured.

When the control light is irradiated to the ultra-high-speed photoresponsive film, the absorptivity of the medium decreases only while the control light is irradiated. When the irradiation of the control light is stopped, the recovery time constant is 5 ps or less, preferably 500 fs. (femtoseconds) or less (1 fs = 10
^{At -15} s), the change in the absorptance returns to its original value, so that a very fast response can be obtained. In addition, in the present invention, when the ultrafast photoresponsive film is irradiated with control light, the ultrafast photoresponsive film simultaneously changes not only the absorptance but also the refractive index. A larger extinction ratio can be obtained as compared with a case where only a change in absorptance due to absorption saturation of the response film is used.

As shown in FIG. 2, for example, the absorptance k of an ultrafast photoresponsive film comprising a J-aggregate of squarylium dye
Changes according to the wavelength, and reaches a maximum at a wavelength of about 770 nm. That is, it has a maximum absorption peak at a wavelength of about 770 nm. Further, the refractive index n of the ultrafast photoresponsive film also changes according to the wavelength, and reaches a maximum at a wavelength of about 780 nm. When the ultrafast photoresponsive film is irradiated with control light having a wavelength near the maximum absorption peak, as shown in FIG. 3A, the absorptance of the ultrafast photoresponsive film for light having a wavelength of about 770 nm decreases.
As shown in (B), the refractive index for light on a longer wavelength side than 770 nm where the absorption peak of the ultrafast photoresponsive film is slightly decreased. The change in the refractive index occurs in a wavelength range wider than the change in the absorptance. When the irradiation of the control light is stopped, the changes in the absorptance and the refractive index are expressed by the following formulas (1) and (2).
Return within 00 fs.

In the multi-channel optical switch according to the present invention, when a serial light signal consisting of signal light having a predetermined beam shape is incident from the light incident portion by the signal light incident means, the control light irradiation means is turned on by each of the incident light signals. When different beam parts are reflected in the direction perpendicular to the incident direction in the plane of incidence of the signal light,
Since the control light is applied to the ultrafast photoresponsive film, a serial signal light train can be converted into a spatially separated parallel signal light train.

In the above-described multi-channel optical switch according to the present invention, the signal light incident means reflects one end of the first signal light in the signal light train made up of a predetermined number of incident signal lights by the light reflecting portion. When the signal light is incident such that the other end of the last signal light of the signal light train is reflected by the light reflecting portion, the control light irradiating means reflects one end of the first incident signal light. Then, the control light can be irradiated once so that the other end of the last signal light that has entered is reflected. Thereby, a serial signal light sequence can be collectively converted into a spatially separated parallel signal light sequence. At this time, parallel signal lights arranged one-dimensionally in a direction perpendicular to the reflection direction in the incident plane are obtained.

In the case where the signal light having the predetermined beam shape is incident from the light incident portion at an incident interval longer than the time from when one end of the incident signal light is reflected to when the other end is reflected. Also, the control light irradiating means irradiates the control light in synchronization with a predetermined beam portion of each signal light being reflected, thereby converting a serial signal light train into a spatially separated parallel light. It can be converted into a signal light train.

The control light irradiating means may irradiate the control light at different timings for different regions within the region of the ultra-high-speed photoresponsive film irradiated with the control light. This makes it possible to convert a serial signal light sequence into a spatially separated parallel signal light sequence corresponding to different regions within the region of the ultrafast photoresponsive film irradiated with the control light.

For example, when a region to be irradiated with control light is divided along a direction perpendicular to the incident surface, and control light is irradiated at different timings for each of the divided regions, one region is irradiated in a direction perpendicular to the incident surface. A parallel signal light train arranged in a dimension is obtained. At the same time, if parallel signal light trains one-dimensionally arranged in the direction perpendicular to the reflection direction in the incident surface are obtained, the direction perpendicular to the reflection direction in the incident surface and the incidence surface , A parallel signal light train two-dimensionally arranged in a direction perpendicular to the above is obtained.

The different timing of irradiating the control light may be a timing synchronized with the incidence of each signal light train on the light reflecting portion. For example, by changing the waveguide speed or the optical path length of the control light, the timing of irradiating the control light can be made different.

On the other hand, the above-mentioned signal light incident means may make the signal light beam incident at different timings for different regions of the light incident portion. For example, by changing the waveguide speed or the optical path length of the signal light, the timing at which the signal light train is incident can be made different. This makes it possible to convert a serial signal light sequence into a spatially separated parallel signal light sequence.

For example, when signal light trains are incident at different timings for different regions arranged along the direction perpendicular to the incident surface of the light incident portion, one signal beam is applied in the direction perpendicular to the incident surface.
A parallel signal light train arranged in a dimension is obtained. At the same time, when one-dimensionally arranged parallel signal light train in the direction perpendicular to the reflecting direction at the plane of incidence is to be obtained is perpendicular and incident plane in the reflection direction in the plane of incidence , A parallel signal light train two-dimensionally arranged in a direction perpendicular to the above is obtained.

In the above-mentioned multi-channel optical switch of the present invention, the above-mentioned ultra-high-speed light responsive film can be constituted by an ultra-high-speed light responsive film whose absorptance and refractive index change by a nonlinear optical effect. This ultrafast photoresponsive film is preferably composed of an aggregate of organic compounds, and the organic compound is preferably a squarylium dye represented by the following general formula (I). In addition, the aggregate of the organic compound is J
-Preferably it is an aggregate.

[0028]

Embedded image

(R ₁ and R ₂ each represent an alkyl group, and X represents H, F, Cl, OH, CH ₃ , C ₂ H ₅ or OCH _{3. Even if} R ₁ and R ₂ are the same, The control light may be irradiated from a direction inclined toward the signal light incident side with respect to the normal line of the ultrafast photoresponsive film. The wavelength of the control light is preferably a wavelength that resonates with the absorption wavelength of the ultrafast response film.

The wavelength of the signal light can be longer than that of the control light. The wavelength of the signal light is particularly preferably a wavelength at which the ultrafast photoresponsive film does not have absorption. Also, the signal light may be made to enter the film surface of the ultrafast photoresponsive film with p-polarized light or s-polarized light.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) In a reflection type optical switch element according to the present embodiment, as shown in FIG. 1, signal light is incident from one surface 18A other than the inclined surface by signal light incidence means (not shown). In addition, a right-angle prism 10 made of glass is arranged so that signal light is irradiated from the side of the slope 16 by control light irradiation means (not shown). The slope 16 of the right-angle prism 10 has a thickness d. ultrafast photoresponsive film 14 of the _second metal film 12 and the thickness d ₃ are stacked in this order. Note that a glass substrate made of a material having the same refractive index as the right-angle prism 10 may be interposed between the inclined surface 16 of the right-angle prism 10 and the metal film 12.

The metal film 12 is, for example, an Ag (silver) thin film,
u (gold) can be a thin film, for example, it can be formed by a method such as vacuum deposition.

The ultrahigh-speed photoresponsive film 14 is made of a photoresponsive material whose absorption and refractive index change due to the nonlinear optical effect and whose recovery time constant is within 5 ps. Such photoresponsive materials include squarylium dyes,
Organic compounds such as phthalocyanine dyes and pseudoisocyanine bromide, and inorganic compounds such as GaAs-based semiconductors and InP-based semiconductors are exemplified. Further, as the photoresponsive material, an organic compound which forms an aggregate is preferable. An aggregate is a state in which tens to hundreds of molecules are regularly arranged and loosely bound, and behave optically as if they were one supramolecule. J-aggregates are widely known. ing. When an organic compound forms a J-aggregate, the absorption shifts to a longer wavelength and becomes sharper than that of a single molecule. By utilizing this sharp absorption, a very large change in the refractive index can be obtained. In addition, when the organic compound forms a J-aggregate, the lifetime of excitation by light is shortened, and photoresponsiveness is increased.

As the photoresponsive material, a squarylium dye represented by the above general formula (I) is particularly preferable. In the general formula (I), R ₁ and R ₂ each represent an alkyl group, preferably a lower alkyl group having 3 to 7 carbon atoms, and particularly, an n-propyl group, an i-propyl group, and n
-Butyl, i-butyl and t-butyl are preferred. Note that R ₁ and R ₂ may be the same or different. X represents H, F, Cl, OH, CH ₃ , C ₂ H
Represents ₅ or OCH ₃ , with H, OH and CH ₃ being particularly preferred.

The ultra-high-speed photoresponsive film 14 is obtained by dissolving the above-mentioned photoresponsive material in an appropriate solvent, and applying the obtained solution to the metal film 12 by spin coating, cast coating, dip coating, or the like. Can be formed.
Further, the ultra-high-speed photoresponsive film 14 can be formed by a vacuum process such as a vacuum deposition method, an MBE method (molecular beam epitaxy method), or the like.
It can be formed by a gas phase process such as a VD method (metal organic chemical vapor deposition).

In the reflection type optical switch element according to the present embodiment, the signal light is applied to the light incident portion 1 of the right-angle prism 10.
8A. Since generally the incident light is refracted at the interface between air and glass, as shown in FIG. 4, the incident angle phi _0,
The refraction angle and phi _1, the traveling direction and the slope 1 of the incident light in air
The angle between the normal line 6 and the normal line of the slope 16 is θ ₀ , and the angle between the incident light inside the right-angle prism 10 and the normal line of the slope 16 is θ ₁ . FIG. 5 shows the relationship between the angle θ ₀ and the angle θ ₁ in this case.

As shown in FIG. 1, incident light (signal light) incident on the metal film 12 at an incident angle of θ ₁ is mainly reflected on the surface of the ultra-high-speed photoresponsive film 14.
The interface between the right-angle prism 10 (the glass substrate when a glass substrate is attached on the prism) and the metal film 12, the interface between the metal film 12 and the ultrafast photoresponsive film 14, and the surface of the ultrafast photoresponsive film 14. Reflected at the right angle prism 10
Out of the light emitting portion 18B. At this time, when the control light is irradiated to the ultrafast photoresponsive film 14 with a sufficient intensity, the refractive index and the absorptivity of the ultrafast photoresponsive film 14 change, and
The reflectance of the signal light incident from the 0 side fluctuates. After stopping the irradiation of the control light, the original state is restored within 5 ps, and the optical switch operates as an ultra-fast response optical switch.

Hereinafter, the interface between the rectangular prism 10 (or glass substrate) and the metal film 12, the interface between the metal film 12 and the ultra-high-speed photoresponsive film 14, and the surface of the ultra-high-speed photoresponsive film 14 are collectively referred to as a light reflecting portion. I do.

Next, optical switch elements (A) and (B) having the structure shown in FIG. 1 were produced, and the reflection characteristics were measured.
First, as a metal film 12 on a glass substrate, the thickness d ₂ is 20 n.
m silver thin film is vacuum-deposited, and the thickness d ₃ is 100 n
ultrafast photoresponsive film 14 composed of m-squarylium dye
Was formed by spin coating. The glass side of this glass substrate was adhered to the inclined surface 16 of the right-angle prism 10 made of glass using transparent oil, to produce an optical switch element (A). Further, the thickness d ₃ of the ultrafast photoresponsive film 14 is set to 150 n.
m, except that m was used.
An optical switch element (B) was produced. The glass substrate and the right-angle prism made of glass are made of materials having the same refractive index.

Next, as shown in FIG.
The optical switch element (A) is set on the reference numeral 0, and the center wavelength 800 nm, the pulse width 100 fs, and the center wavelength emitted from the signal light irradiation means 22 composed of a titanium sapphire laser are used.
An ultrashort pulse laser beam having a repetition frequency of 80 MHz is polarized by a polarizer 24 in a direction parallel to the paper (p-polarized light),
The light is converted into parallel light by the optical system 26, and the optical switch element (A)
Incident on one side of the right angle prism. As defined in FIG. 4, the angle between the traveling direction of the incident light in the air and the normal to the slope of the right-angle prism is θ _0, and the angle θ ₀ is changed by rotating the rotary stage 20 to change the incident light to the incident light. 2 for
The intensity of the reflected light emitted in the direction of θ ₀ was measured using a photodetector 28 such as a photodiode. Referring to FIG. 5 obtains the incident angle theta ₁ to the light reflecting portion from the angle theta ₀ and to examine the relationship between the reflectance and the incident angle theta _1. Further, for the optical switch element (B), the relationship between the reflectance and the incident angle θ ₁ was similarly examined. FIG. 7 shows the results.

Here, the incident angle at which the reflectance becomes minimum is θ_m
Then, as shown in FIG._ThreeIs 100 nm
In the optical switch element (A), θ_m= 41.4 °,
Film thickness d _ThreeIn the optical switch element (B) of which_m
= 46.4 °. Thus, ultra-fast photoresponsive film
Angle θ at which the reflectivity is minimized according to the thickness_mHas changed
Laser with a very short pulse width of about 100 fs
Even when light enters, the thickness of the
Reflectivity may drop as a result of the formation of standing waves
confirmed.

From the above results, in the optical switch element of the present embodiment, the specific incident angle θ _{m with} respect to the light reflecting portion
It can be understood that the incident light incident on the super-high-speed photoresponsive film 14 is reflected at the minimum reflectance when the ultra-fast photoresponsive film 14 has a specific thickness.

Incidentally, the film thickness d ₂ of the metal film 12, the thickness d ₃ of the ultrafast photoresponsive film 14, and by optimizing the wavelength lambda ₁ of the incident light, the incident angle at which the reflectance is minimum theta _m Can be made close to zero.

Since the reflectance is reduced as a result of the formation of the standing wave in the thickness direction in the ultrafast photoresponsive film 14, the optical switch element according to the present embodiment has a structure in which the incident light is s-polarized light. An optical switch function can be performed regardless of p-polarized light. However, when the incident light was s-polarized light, the reflectance is minimum at a different incident angle theta _m and p-polarized light. Further, when the incident light is p-polarized light, the reflectance at the incident angle θ _m can be closer to 0 than when the incident light is s-polarized light.

Here, in order to form a standing wave, the thickness d ₃ of the ultrafast photoresponsive film must approximately satisfy the condition of the following equation (1). In the following formula (1), m is a natural number (m = 1, 2, 3,...), Λ ₁ is the wavelength of incident light, and n ₃
Represents the refractive index of the ultrafast photoresponsive film 14.

[0046]

(Equation 1)

In other words, the thickness d of the ultrafast photoresponsive film 14
_{If 3} is constant, the refractive index n ₃ of the ultrafast photoresponsive film 14 decreases, and the incident angle θ _{m at} which the reflectance becomes minimum changes. Therefore, when the control light is irradiated to the ultrafast photoresponsive film 14 with sufficient intensity, the refractive index and the absorptivity of the ultrafast photoresponsive film 14 change at the time of irradiation, and the reflection characteristics of the optical switch element change. .

As a specific example, using the optical switch element (B), the wavelength of the incident signal light is 850 nm and the energy per unit area of one pulse of the control light is 40 μJ /.
cm ² , pulse width 200 μs, control light wavelength 770n
FIG. 8 shows the reflection characteristics before irradiation with control light (shown by a solid line) and the reflection characteristics when irradiation with control light (shown by a dotted line) when m is set.

[0049] As shown in FIG. 8, when the control light irradiation, the refractive index of the ultrafast photoresponsive film is 0.05 decreases, the reflection characteristic of the optical switch is changed. As a result, the incident angle θ ₁ = 4
At 4.8 °, the reflectivity increases from 1% to 61%.

As described above, when the reflectance of the incident signal light increases due to the irradiation of the control light, the incident signal light is reflected (on state) during the irradiation of the control light, and the irradiation of the control light is performed. Is stopped, and after a recovery time of 100 to several 100 fs, the refractive index and the absorptivity recover their original values, and the incident signal light is not reflected (off state), so that the optical switch can be operated.

[0051] As shown in FIG. 9, the plane of incidence, the signal light is obliquely incident on the light reflecting portion, when the one end of the optical signal pulse reaches a point A on the inclined surface 16 of the rectangular prism, the signal The other end of the light pulse is at point B, and a time difference Δt ₁ occurs before reaching the point C on the slope 16. The incident angle is θ ₁ ,
Assuming that the beam diameter is D ₁ , the refractive index of glass is n ₁ , and the speed of light in vacuum is c, the time difference Δt ₁ is represented by the following equation. For example, D ₁ = 1 mm, n ₁ = 1.5, θ ₁ = 45 °, c = 3
Assuming × 10 ⁸ m / s, Δt ₁ = 5 ps.

[0052]

(Equation 2)

When the signal light pulse interval τ _s is made shorter than the time difference Δt ₁ (τ _s <Δt ₁ ), as shown in FIG. 10, a plurality of pulses enter different positions on the light reflecting portion at a certain time. Will be. At this time, if the pulse width t _{c of the} control light is shorter than the signal light pulse interval τ _s (t _c <τ _s ), a plurality of signal light pulses (signal light Only the part of the pulse train) incident on the light reflection part is strongly reflected. As a result, each light pulse of the signal light pulse train is reflected to a spatially different position. The distance s between two adjacent signal light pulses at the time when the control light pulse is irradiated is represented by the following equation.

[0054]

(Equation 3)

The interval u between two adjacent signal light pulses on the light reflecting portion is expressed by the following equation.

[0056]

(Equation 4)

For example, τ _s = 1 ps, n ₁ = 1.5, θ ₁
= 45 °, s = 0.2 mm, u = 0.28 mm
And the adjacent signal light pulse is incident on the light receiving surface 40 arranged perpendicular to the outgoing light on the incident surface (XY surface).
In the inside, the light is separated at intervals of 0.2 mm in a direction (Y′-axis direction) perpendicular to the reflection direction (X′-axis direction).

As described above, according to the optical switch element of the present embodiment, the temporally serial signal light pulse train
The light is spatially separated by one control light irradiation and converted into a parallel signal light pulse train arranged in one dimension.

In addition, the ultra-high-speed photoresponsive film has an absorption and a refractive index that change due to the nonlinear optical effect and a recovery time constant of 5
Since it is composed of a photo-responsive material of less than ps, the extinction ratio is improved by changing the refractive index and the absorptance of the ultra-high-speed photo-responsive film at the time of irradiation with the control light, thereby greatly changing the reflectivity. In addition, the original state can be restored within 5 ps, and the device can be operated as an ultra-high-speed optical switch. Furthermore, the optical switch function can be performed regardless of whether the incident light is s-polarized light or p-polarized light.

(Second Embodiment) The reflection type optical switch element according to the second embodiment has the same configuration as that of the first embodiment except that a delay unit is arranged on the optical path of the control light. Therefore, the same components are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 11A, a delay unit 30 is arranged outside the light reflecting portion on the inclined surface 16 of the right-angle prism 10 and in parallel with the inclined surface 16 so as to intersect with the optical path of the control light. ing. The delay device 30 is made of a transparent medium such as glass, and as shown in FIG. 11B, the thickness of the delay device 30 is set in the longitudinal direction of the right-angle prism 10 (the direction orthogonal to the incident surface, the Z-axis). direction), (in this embodiment d ₄ and _{d 5 (d 4> d 5} ) multi-stage stepped and has a structure that changes in two steps). Here, assuming that the refractive index of the transparent medium constituting the delay unit 30 is n and the step of the delay unit 30 is h, light vertically incident on the delay unit 30 has a delay of τ _d per stage.

[0062]

(Equation 5)

For example, in this embodiment, n = 1.
5, h = 2.4 mm, τ _d = 4 ps, and when the control light pulse passes through the portion of the delay device 30 having the thickness d ₄ and when the control light pulse passes through the portion having the thickness d ₅ , A time difference of 4 ps occurs before the light enters the ultrafast photoresponsive film 14.

The control light pulse that has entered the delay device 30 includes a control light pulse that has passed through the portion of the delay device 30 having the thickness d ₄ ,
The control light pulse which has passed through the portion having the thickness d ₅ is split into the control light pulse which has passed through the portion having the thickness d ₅ , and the thickness d ₄
Control pulse that has passed through the portion enters delayed by a delay time tau _d ultrafast photoresponsive film 14.

As in the first embodiment, the signal light pulse
Interval τ_sIs the time difference Δt₁Shorter (τ _s<Δt₁)a
At the time, multiple pulses enter different positions on the light reflector
Will do. At this time, the pulse width t of the control light_cIs a signal
Light pulse interval τ_sShorter (t _c<Τ_s) And first, the thickness
d_FiveThe control light pulse that has passed through
Instantaneously, the light of multiple signal light pulses (signal light pulse train)
Only the part incident on the reflection part is strongly reflected. Late for this
Delay time τ_dJust delayed, the thickness d_FourControl light passing through
At the moment when the pulse enters the light reflector, the signal light pulse train
Only the part of each light pulse that enters the light reflector is strongly reflected.
It is.

As a result, each light pulse of the signal light pulse train is reflected to a spatially different position. That is, the adjacent signal light pulse is reflected on the light receiving surface 40 arranged perpendicular to the outgoing light within the incident surface (XY plane) in the reflection direction (X
(Y-axis direction) perpendicular to ('Y-axis direction) at a predetermined interval, and the first reflected signal light pulse and the next reflected signal light pulse
The light is separated at predetermined intervals in a direction perpendicular to the incident surface (Z-axis direction).

As described above, according to the optical switch element of the present embodiment, the control light is applied to the divided regions of the ultra-high-speed photoresponsive film at different timings by the step-like delay device. A serial signal light pulse train is converted into a parallel signal light pulse train spatially arranged two-dimensionally.

The ultra-high-speed photoresponsive film has an absorption and a refractive index that change due to the nonlinear optical effect and a recovery time constant of 5 μm.
Since it is composed of a photo-responsive material of less than ps, the extinction ratio is improved by changing the refractive index and the absorptance of the ultra-high-speed photo-responsive film at the time of irradiation with the control light, thereby greatly changing the reflectivity. In addition, the original state can be restored within 5 ps, and the device can be operated as an ultra-high-speed optical switch. Furthermore, the optical switch function can be performed regardless of whether the incident light is s-polarized light or p-polarized light.

(Third Embodiment) The reflection type optical switch element according to the present embodiment is different from the first embodiment in that a distributor for distributing signal light to a plurality of channels is arranged in the optical path of the signal light. Since the configuration is the same as that of the embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 12, an optical fiber 32 and an optical waveguide device as a distributor for distributing the signal light guided by the optical fiber 32 to a plurality of channels are provided on the light incident side of the light incident portion 18A of the right-angle prism 10. And a microlens for shaping the signal light output from each channel of the optical waveguide element. In each channel of the optical waveguide element 34, as shown in FIG.
An optical path length difference is provided so that a predetermined delay time occurs between channels.

[0071] The signal light guided by the optical fiber 32 is distributed to a plurality of channels by waveguide element 34, it is delayed by a delay time tau _o for each channel, is emitted from each channel. Light emitted from each channel of the optical waveguide device 34 is a beam shaping by the microlens 36 are sequentially incident from the light incident portion 18A of the right-angle prism 10.

Looking at each channel, similar to the first embodiment, if the signal light pulse interval τ _s is shorter than the time difference Δt ₁ (τ _s <Δt ₁ ), a plurality of pulses (signals) (Light pulse train) will be incident on different positions on the light reflecting portion. At this time, if the pulse width t _{c of the} control light is shorter than the signal light pulse interval τ _s (t _c <τ _s ), at the moment when the control light pulse enters the light reflecting portion in synchronization with the signal light pulse,
Only the portion of each signal pulse of the signal light pulse train that has entered the light reflecting portion is strongly reflected.

As a result, each light pulse of the signal light pulse train is reflected to a spatially different position. That is, adjacent signal light pulses are separated at predetermined intervals in a direction perpendicular to the reflection direction in the incident surface (XY plane) on the light receiving surface arranged perpendicularly to the outgoing light, and are separated from each channel. The incident signal light pulse is separated at predetermined intervals on the light receiving surface in a direction perpendicular to the incident surface (Z-axis direction).

As described above, according to the optical switching device of the present embodiment, the signal light is distributed to a plurality of channels by the optical waveguide device, which is an optical distributor, and the signal light is distributed at different timings for each of the distributed channels. Since the light is incident from different regions of the light incident portion of the prism and is reflected at different positions of the light reflecting portion, the temporally serial signal light pulse train is converted into a spatially two-dimensional parallel signal light pulse train. Is converted.

Further, the ultra-high-speed photoresponsive film has an absorption and a refractive index which change due to the nonlinear optical effect, and a recovery time constant of 5
Since it is composed of a photo-responsive material of less than ps, the extinction ratio is improved by changing the refractive index and the absorptance of the ultra-high-speed photo-responsive film at the time of irradiation with the control light, thereby greatly changing the reflectivity. In addition, the original state can be restored within 5 ps, and the device can be operated as an ultra-high-speed optical switch. Furthermore, the optical switch function can be performed regardless of whether the incident light is s-polarized light or p-polarized light.

In the first to third embodiments, the incident direction of the control light is set to a direction substantially perpendicular to the ultra-high-speed photoresponsive film. However, as shown in FIG. The direction may be inclined to the signal light incident side with respect to the normal of the inclined surface 16 of the right-angle prism 10 (common to the normal of the ultrafast photoresponsive film 14). When the incident direction of the control light is inclined toward the signal light incident side with respect to the normal line of the ultrafast photoresponsive film, it is possible to reduce a decrease in reflectance due to a difference in arrival time of the signal light pulse.

When the control light is obliquely incident as described above, a time difference also occurs at the time when the control light pulse reaches the slope 16. The time difference Δt _c is the time when the control light travels from the point D to the point C. Assuming that the incident angle is θ _c and the beam diameter is C, the time difference Δt _c is represented by the following equation. For example, θ _c =
45 °, D ₁ = 1 mm, θ ₁ = 45 °, c = 3 × 10 ⁸ m
/ S, Δt _c = 3.3 ps.

[0078]

(Equation 6)

Therefore, in order to efficiently change the reflectance of the signal light when the control light is obliquely incident, the pulse width t _s of the signal light, the pulse width t _c of the control light, and the time difference Δt
₁ and the time difference Δt _c preferably satisfy the following relational expression.

[0080]

(Equation 7)

In the first to third embodiments, it is preferable that the wavelength λ ₀ of the control light resonates with the maximum absorption peak wavelength of the ultrafast photoresponsive film. When the wavelength λ _{0 of the} control light is near the maximum absorption peak wavelength of the ultrafast photoresponsive film, the change in the absorptance and the refractive index of the ultrafast photoresponsive film are maximized, and the extinction ratio is improved. For example, as shown in FIG. 3A, an ultrafast photoresponsive film made of a squarylium dye thin film having an absorption peak at a wavelength of about 770 nm has an absorptance when the wavelength of the control light is 770 nm. The change is greatest.

The wavelength λ ₁ of the signal light can be selected to be different from the wavelength λ _{0 of the} control light. In the conventional optical switch element, the wavelength λ _{1 of the} signal light is often set to a wavelength near the maximum absorption peak wavelength of the ultrafast photoresponsive film, similarly to the wavelength λ _{0 of the} control light. In the optical switch element, the wavelength selection range of the signal light is wide, and the wavelength can be other than the maximum absorption peak wavelength of the ultrafast photoresponsive film. For example, the wavelength λ _{1 of the} signal light can be longer than the maximum absorption peak wavelength of the ultrafast photoresponsive film.
The wavelength λ ₁ of the signal light is preferably a wavelength at which the ultrafast photoresponsive film has no absorption in order to reduce the absorption loss of the signal light.

In the first to third embodiments,
By condensing the control light, the energy per one pulse of the control light can be reduced. Further, the reflected light may be condensed by a cylindrical lens and introduced into an optical fiber.

In the first to third embodiments, the right angle prism is used as the light transmitting member having the light incident portion and the light emitting portion, but the light is incident on one surface from the light incident portion. There is no particular limitation as long as an ultra-high-speed light-responsive film can be formed so as to reflect the signal light in the direction of the emitting portion. For example, the shape can be a semicircle or the like.

The multi-channel optical switch of the present invention, as in the second and third embodiments, converts a time-serial signal light pulse train into a spatially two-dimensional parallel light signal. By converting the signal into a signal light pulse train, for example, in optical transmission of image information, the transmitting side multiplexes parallel two-dimensional image information on m × n pixels into serial signal light and transmits it. The multiplexed serial signal light is spatially converted into m channels in one axis direction and n channels in another orthogonal axis direction.
If separated into two-dimensional parallel signal light, parallel two-dimensional image information for m × n pixels is directly processed or detected by a two-dimensional spatial light modulator or two-dimensional CCD array while maintaining two-dimensional parallelism. It is possible to do.

Further, the multi-channel optical switch of the present invention can be used as an optical logic element for optical operation or the like.

[0087]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. (Example 1) a silver thin film having a thickness of d ₂ is 35nm on a glass substrate by vacuum deposition, spin coating ultrafast photoresponsive film 14 whose thickness d ₃ above consists of squarylium dye J aggregate of 190nm Was formed. The glass side of this glass substrate was adhered to the inclined surface 16 of the right-angle prism 10 made of glass using transparent oil, to produce an optical switch element (C) having the configuration shown in FIG. The refractive index n ₃ of the ultrafast photoresponsive film 14 at a wavelength of 850 nm was 2.68.

As shown in FIG. 10, an optical pulse train (signal light) having a wavelength of 850 nm and a pulse width of 0.2 ps is converted into a parallel beam having a beam diameter of 1 mm, and is substantially formed on one side of the right-angle prism of the optical switch element (C). Normally incident. The incident optical signal is obtained by repeatedly arranging a pulse train composed of four serial pulses at an interval of 1 ps at a predetermined interval. When the intensity of the reflected light was measured using a photodetector, the relationship between the reflectance and the incident angle θ ₁ was as shown by the solid line in FIG. 8, and the reflectance was measured when the incident angle θ ₁ was 44.8 °. Showed a minimum value of 1%.

The incident angle θ ₁ was fixed at 44.8 °, and control light was perpendicularly incident on the ultrafast photoresponsive film 14 in synchronization with the incident light. The wavelength of the control light was 780 nm, the beam diameter was 2 mmφ, the pulse width was 0.5 ps, and the energy per pulse was 0.25 μJ. At the time of control light irradiation, four signal light pulses are incident on different positions on the light reflecting portion in a portion irradiated with the control light, and at the moment one control light pulse is incident on the light reflecting portion, Only the portions of the two signal light pulses that have entered the light reflecting portion are strongly reflected. as a result,
On the light receiving surface 40 arranged perpendicular to the outgoing light, as the reflected light, as shown in FIG.
4) spatially separated at equal intervals of 0.2 mm in a direction (Y′-axis direction) perpendicular to the reflection direction (X′-axis direction)
One pulse was obtained. That is, a temporally serial signal light pulse train could be converted into a spatially parallel signal light pulse train by the optical switch element (C) and extracted. The width in the direction (Z-axis direction) orthogonal to the plane of incidence of each pulse is about 1.0 mm.

Also, the portion of the ultrafast photoresponsive film 14 irradiated with the control light has a difference of Δn ₃ = − with respect to the light having a wavelength of 850 nm.
Although a refractive index change of 0.05 occurred, the original refractive index value was recovered after a recovery time of several hundred fs, and an ultra-high-speed response was exhibited. When the control light was irradiated, the reflectance of the optical switch element increased to 15%. This means that an extinction ratio of 10: 1 or more has been achieved.

Example 2 A glass substrate having a thickness d ₂ of 30
A silver thin film having a thickness of 300 nm is vacuum-deposited thereon and the thickness d ₃ is 500
ultrafast photo-response film 1 consisting of squarylium dye of 1 nm
4 was formed by a spin coating method. The glass side of this glass substrate was adhered to the inclined surface 16 of the right-angle prism 10 made of glass using transparent oil, thereby producing an optical switch element (D) having the configuration shown in FIG. The refractive index n ₃ of the ultrafast photoresponsive film 14 at a wavelength of 1.55 μm was 2.05. This thickness d ₃ satisfies the condition of d ₃ > λ / 2n ₃ .

As shown in FIG. 10, the wavelength is 1.55 μm,
An optical pulse train (signal light) having a pulse width of 0.2 ps was converted into a parallel beam having a beam diameter of 1 mm, and was incident substantially perpendicularly to one side of the right-angle prism of the optical switch element (D). The incident optical signal is obtained by repeatedly arranging a pulse train composed of four serial pulses at an interval of 1 ps at a predetermined interval. When the intensity of the reflected light was measured using a photodetector, the relationship between the reflectance and the incident angle θ ₁ was similar to the solid line in FIG. 8, and the reflection was observed when the incident angle θ ₁ was 44.5 °. The rate showed a minimum value of 4%.

The incident angle θ ₁ was fixed at 44.5 °, and control light was perpendicularly incident on the ultrafast photoresponsive film 14 in synchronization with the incident light. The wavelength of the control light was 780 nm, the beam diameter was 2 mmφ, the pulse width was 0.5 ps, and the energy per pulse was 0.25 μJ. At the time of control light irradiation, four signal light pulses are incident on different positions on the light reflecting portion at the portion irradiated with the control light, and at the moment one control light pulse is incident on the light reflecting portion, Only the portions of the two signal light pulses that have entered the light reflecting portion are strongly reflected. as a result,
On the light receiving surface 40 arranged perpendicular to the outgoing light, as the reflected light, as shown in FIG.
The surface) in a reflection direction (X'-axis direction) perpendicular to a direction (Y'-axis direction), it is spatially separated at regular intervals of 0.2 mm 4
One pulse was obtained. That is, a temporally serial signal light pulse train could be converted into a spatially parallel signal light pulse train by the optical switch element (D) and extracted. The width in the direction (Z-axis direction) orthogonal to the plane of incidence of each pulse is about 1.0 mm.

The portion of the ultra-high-speed photoresponsive film 14 irradiated with the control light is Δn ₃ = 1.55 μm light.
Although a refractive index change of −0.01 occurred, the original refractive index value was recovered after a recovery time of several hundred fs, and an ultra-high-speed response was exhibited. Further, upon irradiation with the control light, the reflectance of the optical switch element increased to 10%. This means that an extinction ratio of 2: 1 or more was achieved.

(Embodiment 3) As shown in FIGS. 11A and 11B, the optical switch element (C) manufactured in Embodiment 1 has a control on the slope 16 of the right-angle prism 10 outside the light reflecting portion. The thickness changes in two stages of d ₄ and d ₅ (d ₄ > d ₅ ) so as to intersect the optical path of the light and parallel to the slope 16, the refractive index n is 1.5, and the step h (d ₄ −d ₅ ) is a delay device 30 having a thickness of 2.4 mm.
Was placed.

An optical pulse train (signal light) having a wavelength of 850 nm and a pulse width of 0.2 ps was converted into a parallel beam having a beam diameter of 1 mm and incident substantially perpendicularly to one side of the right-angle prism of the optical switch element (C). The incident optical signal is obtained by repeatedly arranging a pulse train composed of eight serial pulses at an interval of 1 ps at a predetermined interval.
It is shaped by an optical system so as to have an elliptical shape of 1 mm in a direction perpendicular to the incident direction within the plane and 2 mm in a direction perpendicular to the incident surface (Z-axis direction). When the intensity of the reflected light was measured using an optical detector, the relationship between the reflectance and the incident angle theta _1, is as shown in solid line in FIG. 8, the incident angle theta ₁ is 4
At 4.8 °, the reflectance showed a minimum value of 1%.

The incident angle θ ₁ was fixed at 44.8 °, and the control light was perpendicularly incident on the ultrafast photoresponsive film 14 in synchronization with the incident light. The wavelength of the control light was 780 nm, the beam diameter was 2 mmφ, the pulse width was 0.5 ps, and the energy per pulse was 0.5 μJ. The shape of the control light was a circle having a diameter of 2 mm.

[0098] when the control light irradiation, the irradiated portion of the control light, four optical signal pulse at the beginning are incident at different positions on the light reflecting portion, passes through the thickness d ₅ parts of delayer 30 At the moment when the control light pulse enters the corresponding region of the light reflecting portion, only the portion of the first four signal light pulses that have entered the light reflecting portion is strongly reflected in the corresponding region. This is delayed by a delay time τ _d = 4 ps,
At the moment when the control light pulse that has passed through the 0-th thickness d ₄ portion enters the light reflecting portion, only the portion of the next four signal light pulses that have entered the light reflecting portion is strongly reflected in the corresponding region.

As a result, on the light receiving surface 40 arranged perpendicularly to the outgoing light, as reflected light, as shown in FIG. 16, in the incident surface (XY plane), the reflection direction (X 'axis direction)
In the direction perpendicular to the plane (Y ′ axis direction), four pulses spatially separated at equal intervals of 0.2 mm, and the four pulses are temporally delayed by 4 ps, and the incident plane (XY
At a position slightly shifted in the direction (Z-axis direction)
A total of eight light pulses of four pulses spatially separated at equal intervals of 0.2 mm in the direction perpendicular to the reflection direction were obtained. That is, the temporally serial signal light pulse train could be converted into a spatially parallel signal light pulse train using the optical switch element (C) and the delay unit 30 and extracted.

Also, the portion of the ultrafast photoresponsive film 14 irradiated with the control light has a difference of Δn ₃ = − with respect to the light having a wavelength of 850 nm.
Although a change in the refractive index of 0.1 occurred, the original refractive index value was recovered after a recovery time of several hundred fs, and an ultra-high-speed response was exhibited. When the control light was irradiated, the reflectance of the optical switch element increased to 16%. This means that an extinction ratio of 10: 1 or more has been achieved.

(Embodiment 4) As shown in FIG. 12, the right-angle prism 10 of the optical switch element (C) manufactured in Embodiment 1 was used.
The optical fiber 32, the optical waveguide element 34 as a distributor for distributing the signal light guided by the optical fiber 32 into four channels, and the light output from each channel of the optical waveguide element 34, on the light incident side of the light incident part 18A. A microlens 36 for shaping the signal light was arranged. Each channel of the optical waveguide element 34 is provided with an optical path length difference of 1.2 mm in vacuum so that a delay of 4 ps occurs between the channels.

Wavelength 85 emitted from optical fiber 32
Optical pulse train (signal light) with 0 nm and pulse width 0.2 ps
Is guided into the optical waveguide element 34 and distributed into four channels, and the signal light output from each channel of the optical waveguide element 34 is passed through the microlens 36 to a beam diameter of 1 m.
m parallel beams were sequentially and substantially perpendicularly incident on one side of the right-angle prism 10 of the optical switch element (C).

The optical signal incident on the optical switch element (C) is a pulse train composed of 16 serial pulses at 1 ps intervals repeatedly arranged at predetermined intervals, and the shape of the signal light is a circle having a diameter of 1 mm. Thus, it is shaped by the micro lens 36.

The two signal lights output from the adjacent channels are separated in the direction (Z-axis direction) orthogonal to the incident surface (XY plane) on the light incident portion 18A of the right-angle prism 10.
It is incident on a position separated by mm. When the intensity of the reflected light was measured using a photodetector, the relationship between the reflectance and the incident angle θ ₁ was as shown by the solid line in FIG. 8, and the reflectance was measured when the incident angle θ ₁ was 44.8 °. Showed a minimum value of 1%.

The incident angle θ ₁ was fixed at 44.8 °, and the control light was vertically incident in synchronization with the incident light. The wavelength of the control light was 780 nm, the pulse width was 0.5 ps, and the energy per pulse was 1 μJ. The beam shape of the control light was an ellipse of 2 mm × 8 mm.

When the last four signal light pulses of the 16 signal light pulses output from the first channel of the optical waveguide element 34 enter different positions on the light reflecting portion,
At the moment when the control light pulse that has entered synchronously enters the light reflecting portion, only the portions of the four signal light pulses that have entered the light reflecting portion are strongly reflected. Delayed by 4 ps, the four signal light pulses from the ninth to the twelfth out of the sixteen signal light pulses output from the second channel of the optical waveguide element 34 have different positions on the light reflecting portion. At the moment when the control light pulse that has entered synchronously enters the light reflecting portion, only the portions of the four signal light pulses that have entered the light reflecting portion are strongly reflected.

Subsequently, the signal is delayed by 4 ps to the light reflecting portions of the fifth to eighth four signal light pulses of the sixteen signal light pulses output from the third channel of the optical waveguide element 34. The incident part is reflected. 4p more
The part of the 16 signal light pulses output from the fourth channel of the optical waveguide element 34, which is delayed by s, is incident on the light reflecting portions of the first to fourth four signal light pulses. Is done.

As a result, as shown in FIG. 17, on the light receiving surface 40 arranged perpendicularly to the outgoing light, the reflected light is reflected in the incident direction (XY plane) in the reflection direction (X ′ axis direction) as shown in FIG.
The four pulses spatially separated at equal intervals of 0.2 mm in a direction (Y ′ axis direction) perpendicular to
Are delayed by 4 ps in time for each of the four channels, and are reflected at positions shifted by 2.0 mm in a direction (Z-axis direction) orthogonal to the incident plane (XY plane) between adjacent channels. In addition, a total of 16 light pulses were obtained. That is, a temporally serial signal light pulse train is
By the optical switch element (C) and the distributor 30, the signal was converted into a spatially parallel signal light pulse train and extracted.

The portion of the ultra-high-speed photoresponsive film 14 irradiated with the control light has a difference of Δn ₃ = − with respect to light having a wavelength of 850 nm.
Although a refractive index change of 0.05 occurred, the original refractive index value was recovered after a recovery time of several hundred fs, and an ultra-high-speed response was exhibited. When the control light was irradiated, the reflectance of the optical switch element increased to 15%. This means that an extinction ratio of 10: 1 or more has been achieved.

[0110]

The multi-channel optical switch of the present invention has a large extinction ratio, can convert a serial signal light sequence into a spatially separated parallel signal light sequence, and has an ultra-high-speed response. Is exerted.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view along an optical axis showing a schematic configuration of a reflection type optical switch element according to a first embodiment.

FIG. 2 is a graph showing the relationship between the absorption coefficient k and the refractive index n and the wavelength of an ultrafast photoresponsive film made of a J-aggregate of a squarylium dye.

FIG. 3A is a graph showing a relationship between a change in absorptance Δk of the ultrafast photoresponsive film and a signal light wavelength when control light having a wavelength near a maximum absorption peak is irradiated, and FIG. Is a graph showing the relationship between the refractive index change Δn of the ultrafast photoresponsive film and the wavelength of the signal light.

FIG. 4 is an explanatory diagram that defines an angle θ ₀ and an angle θ ₁ .

FIG. 5 is a graph showing a relationship between an angle θ ₀ and an angle θ ₁ defined in FIG.

FIG. 6 is a schematic configuration diagram of a measurement system for measuring a reflection characteristic of the optical switch element.

FIG. 7 is a graph showing a relationship between a reflectance and an incident angle θ ₁ .

FIG. 8 is a graph showing the relationship between the reflectance and the incident angle θ ₁ .

FIG. 9 is a diagram illustrating a time difference in a pulse width direction generated when a signal light having a pulse width ts reaches a prism slope.

FIG. 10 is a cross-sectional view taken along the optical axis for explaining a mechanism in which the reflective optical switch element according to the first embodiment converts serial signal light into parallel signal light.

FIG. 11A is a sectional view taken along an optical axis showing a schematic configuration of a reflection type optical switch element according to a second embodiment, and FIG. 11B is a sectional view of the reflection type optical switch element according to the second embodiment; It is the side view which looked at such a reflective type optical switch element from the reflective surface side.

FIG. 12 is a perspective view illustrating a schematic configuration of a reflective optical switch element according to a third embodiment.

FIG. 13 is a plan view showing a configuration of a waveguide formed in an optical waveguide device of a reflection type optical switch device according to a third embodiment.

FIG. 14 is a diagram illustrating a time difference in a pulse width direction generated when control light having a pulse width tc that is obliquely incident reaches a prism slope.

FIG. 15 is a diagram illustrating a spatial arrangement of parallel signal lights output from the optical switches according to the first and second embodiments.

FIG. 16 is a diagram illustrating a spatial arrangement of parallel signal light output from the optical switch according to the third embodiment.

FIG. 17 is a diagram illustrating a spatial arrangement of parallel signal light output from the optical switch according to the fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Right angle prism 12 Metal film 14 Ultra-high-speed photoresponsive film 16 Slope 18A Incident surface 18B Exit surface 20 Rotation stage 22 Light irradiation means 24 Polarizer 26 Optical system 28 Photodetector 30 Delay unit 32 Optical fiber 34 Optical waveguide element 36 Microlens 40 Light receiving surface

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasu Sato, Suburban 430 Green Tech Nakai, Nakai-machi, Ashigara-kami, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Minami Ta, 430 Green Tech Nakai, Nakai-cho, Ashigara-kami, Kanagawa Fuji Fuji Inside Xerox Co., Ltd. (72) Inventor Ryujun Husband 430 Green Tech Nakai, Nakai-machi, Ashigara-gun, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. F term in the company (reference) 2K002 AA02 AB16 BA02 CA05 DA02 EA30 GA10 HA13

Claims (17)

[Claims] A light transmitting member provided with a light incident portion, a light emitting portion, and a surface provided between the light incident portion and the light emitting portion and intersecting an optical path of incident light from the light incident portion; A metal film formed on the surface of the light-transmitting member, and an ultra-high-speed photoresponsive film that is stacked on the metal film and has a refractive index and an absorptivity for signal light that are changed by being irradiated with control light. A light reflecting portion that changes the reflectance of reflecting the signal light incident from the light incident portion in the direction of the light emitting portion when the control light is being irradiated; Optical signal,
A signal light incident unit that is incident from the light incident unit, and a control light is transmitted to the ultrafast light-responsive film when a different beam portion is reflected in a direction perpendicular to an incident direction on an incident surface of each incident signal light. And a control light irradiating means for irradiating light. 2. The signal light incident means according to claim 1, wherein when one end of the first signal light of the incident signal light train composed of a predetermined number of signal lights is reflected by said light reflecting portion, said signal light incident means comprises: incident signal light as the other end of the last signal light is reflected by the light reflecting portion, the control light irradiation means, when the one end portion of the first signal light incident is reflected, incident The control light is irradiated once so that the other end of the last signal light is reflected.
A multi-channel optical switch according to claim 1. 3. The multi-channel light according to claim 1, wherein the control light irradiating means irradiates the control light at different timings for different regions in the region of the ultrafast light responsive film irradiated with the control light. switch. 4. The multi-channel optical switch according to claim 3, wherein the different timing is a timing synchronized with the incidence of each signal light train on the light reflecting section. 5. The timing is varied by changing the waveguide speed or optical path length of the control light.
A multi-channel optical switch according to claim 1. 6. The multi-channel optical switch according to claim 1, wherein said signal light incident means enters said signal light train at different timings for different regions of said light incident part. 7. The multi-channel optical switch according to claim 6, wherein the timing is changed by changing the waveguide speed or the optical path length of the signal light. 8. The multi-channel optical switch according to claim 1, wherein said light transmitting member is a prism. 9. The multi-channel optical switch according to claim 1, wherein said ultra-high-speed light-responsive film has an absorptivity and a refractive index which are changed by a nonlinear optical effect. 10. The multi-channel optical switch according to claim 1, wherein said ultra-high-speed photoresponsive film is made of an association of organic compounds. 11. The multichannel optical switch according to claim 10, wherein said organic compound is a squarylium dye represented by the following general formula (I). [Formula 1] (R ₁ and R ₂ each represent an alkyl group, X is H,
Represents F, Cl, OH, CH ₃ , C ₂ H ₅ or OCH ₃ .
R ₁ and R ₂ may be the same or different. ) 12. The multi-channel optical switch according to claim 10, wherein the aggregate of the organic compound is a J-aggregate. 13. A control light is irradiated from a direction inclined to a signal light incident side with respect to a normal line of the ultrafast photoresponsive film.
13. The multi-channel optical switch according to any one of 12 above. 14. The multi-channel optical switch according to claim 1, wherein the wavelength of the control light is a wavelength that resonates with an absorption wavelength of the ultrafast photoresponsive film. 15. The multichannel optical switch according to claim 1, wherein a wavelength of said signal light is longer than a wavelength of said control light. 16. The multi-channel optical switch according to claim 1, wherein the wavelength of the signal light is a wavelength at which the ultrafast photoresponsive film has no absorption. 17. The signal light according to claim 1, wherein said signal light is incident on said film surface of said ultrafast photoresponsive film as p-polarized light or s-polarized light.
7. The multi-channel optical switch according to any one of 6.