JPS58134621A - Optical switch - Google Patents

Abstract

PURPOSE:To improve the transmission factor of an analyser up to 100% by using a hologram as the analyser for an optical switch consisting of a ferrodielectric substance and a polarizer and an analyser putting the ferrodielectric substance between them. CONSTITUTION:A PLZT plate 13 has many signal electrodes 15 opposed to a common electrode 14, the polarizing surface of the polarizer 11 makes 45 deg. with an electric field applied by the electrodes 14, 15 and a volume type phase hologram 12 is arranged in stead of the analyser. In the hologram 12, the refractive index is changed like a sine wave at a fixed period in a bichromate gelatin film and the stripe direction at the max. refractive index is parallel with the polarizing direction of the polarizer 11. The light from a light source 10 is straightly polarized by 45 deg. from the applied electric field by the polarizer 11; the incident light to a signal electrode part to which voltage is not applied is transmitted through the PLZT plate and completely diffracted by the hologram 12 and the incident light to a signal electrode part to which voltage is applied is rotated by 90 deg. at its polarizing surface and passed through the hologram 12 without diffraction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical switch comprising a ferroelectric material exhibiting an optical effect and an i/'' polarizing element placed between the ferroelectric materials.

Conventionally, an optical switching element has two parts as shown in FIG.
A PLZT board is used as a ferroelectric material that exhibits the so-called Kerr effect, and a cage 4.5 is installed to apply an electric field to the PLZT board 3'D source switch section. 0 placed between the polarizing plates 1.2
The full i-plane of these polarizing plates 1 and 2 is the electric field mark 7 of the PLZT substrate.
111 direction and 45.

The light from the light source becomes linearly polarized by polarizing plate II/C.
The light is incident on the LZT substrate 3. When no electric field is applied to the wl pole 4.5, the light transmitted through the PLZT plate is blocked by the polarizing plate 2. On the other hand, when an appropriate surface pressure is applied to the electrical resistance 4.5, the light transmitted through the PL Z T plate is polarized by 901d due to the electro-optic effect and is transmitted through the polarizing plate 2.

The polarizing plate of such a light switching element (2) is usually a Kokuko film, which is a polymer film with a pleochroic dye absorbed; Even when linearly polarized light with a surface is incident, the warpage transmittance is only about 75 degrees, and the main string loss is large.

The present invention attempts to obtain the transmittance of an analyzer by using a volume type phase hologram tube instead of one photon and two photons as an analyzer.

Fig. 2 is a rigid representation of the 1.1 gram on an equally spaced linear grid. This hologram is a phase hologram in which the refractive index of the hologram medium changes in a sinusoidal manner, and the refractive index of the hologram medium 6 is the maximum (f). Figure 2<a)? rhoij
The distribution of fringes within 1,000 planes of Gram medium 6 is shown in the same figure collection).
It shows the distribution within the cross section.

Fig. 2 jb), stripe spacing total D% striped hologram cloth + fll'I] eggplant meat φ, 1 of the hologram!
7. If d is the volume type phase hologram, the diffraction efficiency is expressed as follows.

The linearly polarized light experienced by the polarization vector ic is the incident light uc
When incident on the above hologram with
/2nD, where λ is the wavelength of the incident light, n is the hologram medium), and n is the uniform refractive index, and n is the refractive index.
The polarization vector of the 11-digit diffraction source, (fc-111 is the inner product of the vectors, and C3 US=coa ←/c(cost me --COB
φ )... (2) nl) is represented.

In addition, in a volume type phase hologram, both the 0th-order transmitted light and the 1st-order diffracted light exist7, so the above Yt indicates the diffraction efficiency of the 1st-order 1st-order diffracted light.

1. In the relationship between the hologram and the incident light, πrr 1
/λG−“4...If (3) holds true, what is the diffraction efficiency from equation (1)?=Sin2[÷(ic−
ill ]・', 4), and it depends on the polarization direction (linear polarization vector).

Hereinafter, the vector ic is expressed as the x, y% 2 coordinates of Figure 2 + 1). Kototoshi, Q.・ 1 1st 1f,! 1 fold 9:ri] Diffractive 01 is expressed by the following formula, Φ.

Su・□・:,,,48,. .

s1 = s in-' (s + nejc-1)
-...j5) Now, if the linearly polarized light vector i(.
Regardless of the direction of folding, the linearly polarized light vector i1 of the diffracted light is also (, Ll, 1., t, +), so (jc・11.+=1, and from equation f, 4), 17=
[ol diffraction efficiency becomes 11 J u %-.

On the other hand, if the light is polarized perpendicular to the lattice fringes 7, then 1c = (C
O8Flc111,) eyes 1θC), and (b) the polarization vector of the finger light is □beil = + co Sζill, II
% 5ins1 1.

Therefore, the diffraction efficiency rl is obtained from the formula 4) as 'l=5in2(-'-(co time(, acos-no+5inetc*5inejll):l:81n
2(-'-C(1(tyc-Bl)) ,,,
+, 6). Here, if Oc"l=π/2, then l1=t+, and the diffraction efficiency is O, giving zero-order transmitted light.

Substituting this Oc-θl=π/2 into equation (5), we get 81
nedc+c O5dc=λSinφ/1). -1
]=λ sinφ/(sin(nc+c o a&(1
) - (7) Town 2), (3J
From the formula, n, nl, and d are determined depending on the hologram material, and since the wavelength λ of light is known, (7), 1) l) From the formula) 2' = l) The spacing between the stripes and the depth φ formed by the stripes and the hologram redirection can be determined.

If determined in this way or using a hologram with φ as an analyzer, it will be possible to obtain the PLZT board by switching from 1 gram to the 0th order light and -next order light. I can do it.

l of the original switching array constructed from optical switches based on the above principle! ! The arrangement is shown in Figure 3. PLZT
The substrate 13 has a large number of electrodes 1 facing the common electrode 14.
5, and similar to those conventionally known, the polarizing plate ll has a plane of polarization 45" with respect to the electric field applied by the electrodes 14.
It is placed in a structure that forms an angle of 1. Hologram I2 can be seen instead of the optical element, but this hologram is a volume-type phase hologram, for example, a chromic acid gelatin coated on a cuff substrate, and a constant sinusoidal waveform formed in the chromic acid gelatin. The refractive index changes periodically. The figure shows the maximum refractive index fringes f as in Figure 2, but the warp direction is parallel to the plane of polarization of the polarizing plate 11.

The light from the light source IO enters the PLz'r plate from the polarizing plate 11vc as a straight line light inclined by 45 with respect to the applied electric field, and the polarized light that enters the signal electrode part to which no voltage is applied is as follows. 2) The light passes through the PLZT board and enters the hologram 12, following the 1-ura light that is exactly parallel to the lattice stripes. When the VC1 refraction efficiency is I as described in 9) above,
LIU%, and all incident light to the hologram has a diffraction angle of O
Turn with c.

jfu).

On the other hand, the 11% polarized light enters the bologram with voltage i applied to the PLZT board, and the polarization plane is perpendicular to the lattice fringes of the hologram. With a diffraction efficiency of ViO, all of the incident light passes through the hologram without being diffracted. Using this transmitted light or diffracted light, it is possible to obtain the effect of an optical switching array.The hologram used for this optical switching element can be manufactured as shown below.

Hologram Hege] The entrance angle Uc ax is 0, the light source is for green fluorescent lamp f tc (7 center wavelength λ = 055nrn,
The hologram medium is salt chromate gelatin, @tllr*
n = 1.55, large and small refractive index, 11. =
0,01, FJ length d = 20 μm, (7
), (8) formula % formula %) are obtained. That is, a volume-type phase hologram with a grating interval of 0444 μm and a depth of 5386° between the grating stripes and the hologram surface within the periphery may be fabricated.

An example of such a hologram recording optical system DI is shown in FIG. 1 is also child 1... When the distance is converted to the lattice spacing lJo on the six sides of Borodalam, it becomes Do-〇, Liu nφ).

-055 μm.

A hologram medium 491-t for recording a diffraction grating is arranged along the X axis [5. Te4
In order to obtain a 5-square grid, it is arranged at an angle of 17 x 45 with respect to the X axis, as shown in FIG.

A uniformly spaced grid is created by the interference of two waves. In FIG. 4, the emitted light from the laser 41 is converted into parallel light with an approximate Gacus distribution by an objective lens 45, a bottle ball 46, and a collimator lens 47, and the intensity distribution of the light beam is made uniform by a distribution correction filter 48. It becomes The beam splitter 42 splits the light beam into two beams, and one beam is reflected by a mirror 43 and transferred to a hologram recording medium 49Vr.
-Inject at angle d1. The other beam is reflected by the mirror 44 and strikes the hologram recording medium at θ. , and interfered with the other Soviet Union's Light and Song.

These two lights of the Song Dynasty's principal light @ri (4th diagram) are within X - Z d, and the oscillation wavelength of the laser 41 is λ. Then, the required hologram surface spacing). is Holo9) The sum θR formed by these incident light beams D + light - on the gram medium
1θ. 6, 1]. =λ6
(Sin t-*,,,-s in Ho)
,,, 19) In the hologram medium, the curvature becomes φsoft t. Therefore, as mentioned above, D
= 0.55μn1φ = 53.86 If all Ar lasers are used as the laser light source 41, λ. =0488μ
m, and 19) (lO) = 804° θo = 8.1 Ruri], and mirrors 43 and 44 can be set to obtain this shot. A desired hologram can be produced by permanently processing the entire recording of interference fringes [7 hologram records &] 1 medium. .

Note that the hologram recording medium is not limited to galvanized romic acid gelatin, but may also be any volume-enhancing medium, such as #4 white fII salt dry plate, as long as it is a medium for producing a T4 hologram.

In addition, not only transmission type holograms but also reflection type holograms can produce the same effect, and not only volume type phase holograms but also surface relief type holograms can be used to achieve high diffraction efficiency. If you can obtain it, you can use it in the same way.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a known optical switching element 2) #1 configuration, FIG. 2 is an explanatory diagram of a volume type phase hologram, and FIG. 3 is an explanatory diagram of the configuration of an optical switching array according to the present invention.
Figure 5 is a block diagram of the optical system for producing a hologram used in the optical switching element of the present invention. l, 11: Light control plate 2: Light control plate 3.13: PI, ZT
Plate 4.5.14.15: [l & 6° 49: Hologram medium * 7: Lattice stripe lo: Light source 12: Hologram 41: Laser 46: Bin hole 48: Distribution correction filter...: Par Patent applicant Ricoh Co., Ltd. 11) Yu 1 Figure 2] 71 (a) (BL Calculation Figure 5

Claims (1)

[Claims] In an optical switch consisting of a ferroelectric material exhibiting a two-dimensional electrical effect, and a polarizer and an analyzer placed across it,
An optical switch characterized in that a hologram is used as the analyzer.