JPS6151768B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention splits light of a plurality of wavelengths into separate fibers for each wavelength, and splits light of different wavelengths into a single fiber.
This article relates to an optical splitter/combiner that combines into two fibers.

The present applicant proposed an optical splitter/combiner in Japanese Patent Application No. 1983-2124. Its structure is as shown in FIG. A light transmitting mirror 1 (hereinafter referred to as a filter) that reflects light of a predetermined wavelength and transmits light of other wavelengths is formed on the end face of a self-focusing rod lens 3 with a period length of 1/4, and a reflecting mirror is provided behind it. 2 is formed. The light 8 emitted from the fiber 5 is reflected by the filter 1 at a predetermined wavelength and is focused on the end face of the fiber 6. On the other hand, the light transmitted through the filter 1 is reflected by the reflecting mirror 2, passes through the lens 3, and passes through the fiber 7.
It is designed to converge on the end face of the

In this structure, the incident angles at which the light rays 8 and the light rays 10 enter the filter 1 are generally different, and the transmission characteristics of the filter 1 are different.

The present invention utilizes this difference in transmission characteristics to provide an optical splitter that can improve the demultiplexing characteristics.

The present invention will be explained below based on examples together with the drawings.

In FIG. 1, the input fiber 5 and the lens axis 4
FIG. 2 shows the transmission characteristics of the long-wavelength transmission filter when the distance d from the long wavelength transmission filter is changed. When the distance d is increased, the transmission curve shifts to the shorter wavelength side. Therefore, when configuring a two-wave demultiplexer using this filter, by arranging the output fiber 7 for the long wavelength light λ ₂ on the axis as shown in FIG. 3, the short wavelength light λ ₁ is input to the fiber 7. Leakage can be reduced.

In FIG. 4, curves 11 and 12 are the emission spectra of the light emitting diode, and curves 13 and 14 are the transmission characteristics of the filter when d=0.5 mm and 0 mm, respectively. Therefore, if the configuration is as shown in FIG.
The characteristic when the light is transmitted through the filter again after being reflected by the filter becomes the characteristic shown by the curve 14, and the leakage of the light having the wavelength λ ₁ can be reduced.

In the experiment, a lens with a diameter of 2 mm was used, the distance d from the fiber axis was set to 0.6 mm, and the wavelength was 820 mmλ.
₁ , 890 mm When light with wavelength λ ₂ is demultiplexed, the loss of wavelength λ ₂ light is 0.96 dB, and the fiber 7 of wavelength λ ₁ light is
When placed on the lens axis as shown in the figure, the loss of wavelength λ ₂ is 1.02 dB and the leakage of light with wavelength λ ₁ to fiber 7.
It became 30dB.

That is, according to the present invention, leakage can be reduced without significantly increasing loss.

In addition, when the filter 1 is a short wavelength transmission filter, the transmission characteristics shift to the short wavelength side as the incident position becomes farther from the lens axis. A similar effect is produced by making the connection position of the fiber 6 farther from the axis than the connection position of the fiber 6 where the light enters.

As explained above, according to the present invention, it is possible to prevent the light from the light emitting source on the side that is reflected from leaking into the light from the light emitting source on the side that passes through the filter without significantly increasing the loss, and to prevent the signal S/ N can be improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the optical splitter/combiner proposed by the applicant, Fig. 2 is a filter characteristic diagram of the same, Fig. 3 is a block diagram of main parts showing an embodiment of the present invention, and Fig. 4 is a filter characteristic diagram of the same example. DESCRIPTION OF SYMBOLS 1... Light transmission mirror, 2... Light reflector, 3... Self-focusing rod lens, 4... Lens axis, 5... Fiber for incident light, 6, 7... Fiber for output light.

Claims (1)

[Claims] 1 A self-focusing type lens having a period length of 1/4 and a first light-transmitting mirror provided on one end surface of the self-focusing type lens that reflects light of a predetermined wavelength and transmits light of other wavelengths, and the light beam. In the light branching/combining device comprising a light reflector that reflects light of the other predetermined wavelength and is provided at an angle with respect to the axis of the self-focusing lens on the outside of the transmitting mirror, the light transmitting When the mirror transmits light in a long wavelength region, the distance between the focused position of the transmitted light of the other wavelength and the axis of the self-focusing type lens is the distance between the incident position of the light and the axis of the self-focusing type lens. When the light reflector is tilted so that it is longer than An optical branching/combining device characterized in that the reflector is inclined so that the distance between the light incident position and the axis of the self-focusing lens is shorter than the distance between the light incident position and the axis of the self-focusing lens.