JPS58207006A - Optical circuit - Google Patents

Abstract

PURPOSE:To obtain easily an output pulse whose delay time is different in accordance with an incident point, by forming a concentric circle-like spiral part between a light incident part of an optical waveguide group and a light emitting part. CONSTITUTION:Optical fibers 10-13 are formed in parallel from a light incident point 15 to a position shown by a broken line 14, but after the broken line 14, they are formed like a concentric circle spiral, and its concentric circle spiral part ends at a point of the reverse side of the broken line 14 exactly, and after that point, it is formed in parallel to a light output part 16. The optical fiber 10-13 are all the same in its overall length from the incident point 15 to the broken line 14, therefore, an optical pulse signal which is made incident at the same time passes through the broken line 14 part at the same time, and passes through the optical path length corresponding to circumferential radiuses r1-r4 of each optical fiber 10-13 whenever it turns round the concentric circle spiral from the broken line 14 part, therefore, an optical pulse in each optical fiber 10-13 which reaches the output end 16 becomes an optical pulse signal which time is delayed in proportion to the overall length of each optical fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical circuit that obtains output pulses with different delay times corresponding to input points in an optical transmission line.

First, the principle of this invention will be explained below using FIGS. 1 and 2. In Fig. 1, (2) is an optical fiber of length t, and when a light pulse input (1) is input to the input end of this optical fiber (2), the optical fiber (2)
The optical pulse output (3) arrives at the output end of.

To show this temporal relationship, FIG. 1(b) is the input pulse waveform, and FIG. 1(c) is the output pulse waveform.

io is the incident time, 11 is the exit time, and 11-10-
Δl corresponds to the required rate of light e (1) for a light pulse to pass through this optical fiber.

O If we consider two types of t, we get 4 as shown in Figure 2 (cL).
When simultaneous optical pulses (4) and (5) enter an optical fiber (6L (7)) with a length of + t2, the relationship with the optical pulse (8L (9)) arriving at the output end is shown in Figure 2 ( For the input waveform of b), the results are as shown in FIGS. 2(c) and 2(d).

That is, the optical pulse (4) entered the optical fiber (6) with a short length of 1.0 at time 10 reaches the output end at time ll, and enters the optical fiber (7) with a long length t2 at time io. The light pulse (5) reaches the output end at time 12.

? LAI Δi, = i, -4 = - and Δ12 = 4-4 = ”, c
,o
(!Q. It turns out that the time delay Δl is proportional to the length of the optical fiber. This is true not only for optical fibers but also for crystal waveguides with a constant refractive index and various waveguides in gas, liquid, or vacuum. The same is true.

An embodiment of the present invention will be described below with reference to the drawings.

In Fig. 2, QU, (lυ, ab, and a→ are optical fibers, respectively, which are formed in parallel from the light incident point α to the broken line a1, and are formed in a concentric spiral shape from the broken line (l◆). The sections from the end point to the light output section are formed in parallel.

Next, the operation will be explained. From the incident point (11) to the start point of the concentric spiral is an optical fiber (LO~(13 has the same length, so the optical pulse signals that enter at the same time pass through the dashed line 04 section at the same time.One round from the dashed line 04 section) Each time it goes around the center circular thread, the circumferential radius of each optical fiber α0~α is rl
+r2. r3. r4, the optical path length is Δ' for each of the optical fibers (11-(1!
1+Δ'2+Δshi8. Assuming Δ14, FIG. 4 shows another embodiment of the present invention, which differs from FIG. 6 in that the number of optical fibers and the diameter per single core are different. Now consider the physical position 2 where the illumination spot hits. The optical input parts a arranged at regular intervals are arranged in descending order of the cotton wire radius "l+"
When the input spot position is 2/, the time Δl at which the spot is emitted from the light output section αQ becomes a spiral with radius V7 due to the selection of the first waveguide. Δlr×2πV/+RΔl.

Here, RΔl is the parallel waveguide portion transit time, and if the difference between the constant time and the transit time is detected, a time delay proportional to the input spot position will be obtained.

In the above embodiment, the time delay that occurs during one revolution around the spiral concentric circle is obtained in accordance with the displacement of the incident point. It goes without saying that this is appropriate in some cases.Also, although the optical fiber is shown in Fig. 2 as a cylindrical fiber, there is a large amount of loss between the optical signal entering the light input part α and exiting the light output part α0. As long as it is not, it may be composed of a set of rectangular waveguides.In addition, there is no limit to the number of stacked waveguides for an optical circuit made of stacked waveguides, and the size of each waveguide is determined by the size of the waveguide. Needless to say, if it is possible to confine the light of light, there is no particular limitation and it can be set.

As described above, according to the present invention, an optical circuit having a delay time corresponding to the position of the light spot at the input end can be easily obtained.

[Brief explanation of the drawing]

1 and 2 are diagrams showing the principle of the invention, FIG. 6 is a plan view showing an embodiment of the invention, and FIG. 4 is a plan view showing another embodiment of the invention. In the figure, α0. ell), α-pan α→ is an optical fin, 0→ is a light incident point, and αQ is a light output point. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Shin Kuzuno −

Claims (1)

[Claims] An optical circuit characterized in that a concentric spiral portion is formed between a light input portion and a light output portion of an optical waveguide group.