JPS6227363B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical device used in optical switches, optical modulators, etc. in optical fiber communications.

A conventional optical device such as an optical fiber switch is constructed as shown in FIGS. The nickel cylinder 7 is attracted, and the optical fiber 1 is attached to the glass tube 4.
is pressed into either of a pair of opposing V-shaped grooves in the inner wall of the Light-receiving optical fibers 2 and 3 are fitted and fixed in advance into the pair of opposing V-shaped grooves. Therefore, optical fiber 1
The light emitted from the optical fiber 1 is selectively optically connected to the light-receiving optical fiber 2 or the light-receiving optical fiber 3 by reciprocating the pair of opposing V-shaped grooves according to the direction of the magnetic field. Ru.

In the conventional device described above, the optical fiber 1 is directly and violently pressed against the V-shaped groove on the inner wall of the glass tube 4, which may damage the end face of the optical fiber 1 or damage other parts of the optical fiber 1 due to bending stress. It had drawbacks such as being cut off. In addition, since the light emitted from the end faces of the optical fibers spreads, there is a requirement that the distance between the end faces of the fibers must be made small or the optical loss will increase. I didn't have to. Furthermore, since the switch has a mechanical structure, it has the disadvantage that the response is somewhat slow.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide an optical device for an optical switch that utilizes electrical effects to have a fast response speed and less damage to optical fibers and less light loss. There is.

The present invention will be explained below based on embodiments shown in the figures.

In FIG. 3, reference numeral 9 denotes a coherent light source, such as a laser, 10 an optical lens for dividing the light from the light source, 11 a light splitter for optical fibers, 12 and 1
3 is a square refractive index gradient lens having a period length of 1/4 (2m-1) (m = 1, 2...), 14 is a phase diffraction grating, 15 is a variable phase shifter having an electro-optic effect, 2
1, 22, 23 and 24 are optical fibers, and 16 is the spread of the light beam within the lens.

First, the operation of the present invention will be explained using the principle diagram shown in FIG. The light from the coherent light source 9 passes through the Hark mirror 17
It is divided into two by Both lights are further processed by mirrors 18 and 19, respectively, into a thick phase diffraction grating 14.
is made incident on. The grating interval of the phase diffraction grating 14 is Λ.

If the complex amplitudes of the two light waves propagating through this diffraction grating 14 are R and S, respectively, R and
The change in S follows the coupled wave equations (37) and (38) derived from the following process.

The angular frequency of the incident wave is ωi, and the angular frequency of the diffracted wave is ω
d, the distance in the direction across the medium at right angles is Z, and the propagation constants are Ki and Kd. For a phase grating with a grating spacing Λ, Δn(〓)=Δn cos(〓s・〓)
......(20) A refractive index modulation occurs. Here Ks is 2π/Λ
, and γ is a vector indicating the spatial coordinates. As a result of the interaction between this modulation and the electric fields of the ωi and ωd waves, ΔP(〓)=2√ ₀ Δn(〓)e(〓, t)
...(21) Extra electric polarization occurs. Here e(〓, t)
is the sum of the electric field strengths of the ωi wave and the ωd wave.

Now, the wave equation is ▽ ² e(γ, t) = μ ₀ ε∂ ² e/∂t ² +μ ₀ ∂ ² /∂
t ² ΔP(γ) (22). The above formula must be satisfied for each of the ωi wave and the ωd wave. Assuming that both waves are linearly polarized and writing down the equation for the ωi wave, ▽ ² ei=μ ₀ ε∂ ² ei/∂t ² +μ ₀ ∂ ² /∂t ² (
ΔP)i...(23) However, ei is the absolute value of vector ei, (Δ
P)i is the ωi component of the ei direction component of ΔP(〓). Polarized components oscillating at other frequencies are not synchronized. The contribution to ei will be 0 on average. The total electric field e(〓, t) is composed of two traveling wave electric fields ei(〓, t)=1/2R(ri)e ⁱ⁽ 〓 ^it- 〓 ⁱ

Claims (1)

[Scope of Claims] 1. A coherent light source, a branching device that divides the light from the light source into two paths, and a phase diffraction grating that satisfies the Bragg condition for both of the divided light.
An optical device comprising: a phase shifter provided in one of the passages between the branching device and the phase diffraction grating. 2. The above-mentioned phase diffraction grating is installed between a pair of square gradient index lenses, and two incident optical fibers are arranged to make the light from the above-mentioned branching device enter into one of the above-mentioned lenses, and this optical fiber The optical device according to claim 1, wherein the phase shifter is provided in the optical path of one of the lenses, and the output light is obtained through two optical fibers arranged on the other of the lenses. . 3 The phase diffraction grating is installed between a pair of ordinary optical lenses made of a homogeneous refractive index material, and two incident beams are provided for inputting the light from the branching device in front of one of the lenses. A patent claim characterized in that a fiber is arranged, the phase shifter is provided in the optical path of one of the optical fibers, and the output light is obtained through two optical fibers arranged behind the other of the lenses. The optical device according to item 1. 4. The optical device according to claim 1, 2 or 3, wherein the phase shifter is made of a material having an electro-optic effect.