JPS62240907A - Low reflecting line termination - Google Patents

Abstract

PURPOSE:To decrease the reflection effect by making a glass plate having the same optical refractive index as that of an optical fiber waveguide contact the end face of the optical fiber waveguide, and performing a blooming coat to an output end face being distant from the optical fiber waveguide of the glass plate. CONSTITUTION:A line termination contains a guide sleeve 1 which a plug pin 2 passes through, its plug pin contains an optical fiber waveguide which is shaped like a glass fiber 3 and extends coaxially, an end face 4 of the glass fiber 3 carries a glass disk 5, and a blooming coat 6 is provided on an outward output surface of its glass disk 5. The plug pin 2 is connected to an annular flange 9 which works as a bearing to one end of a pressure spring 10. By a force of the spring 10, the end face 4 is pushed to the glass disk 5, and a complete contact is formed between the glass fiber 3 and the glass disk 5. Materials which contact each other at a contact point between the glass fiber 3 and the glass disk 5 have the same optical reflection factor, therefore, a reflection is not generated at all in that place. Accordingly, an influence of a return light by an optical measurement can be easily reduced.

Description

TECHNICAL FIELD OF THE INVENTION This invention relates to low reflection line terminations for optical fiber waveguides that include optical blooming coats that reduce normally occurring reflection effects.

<Prior art and its problems> Reflections occurring at the receiver end of a glass fiber path (which can generally be referred to as an optical fiber waveguide) typically amount to 4% of the optical power. This reflection causes damage to the transmitter end laser. Given that the characterization of fiber optic components is often based on measurements of optical power obtained at the end of a fiber optic waveguide, this reflection is a source of non-reproducible and therefore inconsistent measurements. It may become.

Certain measurements, for example measurements of the reflectivity of optical components by waveguide couplers, can only be performed if all other forms of reflection are at least substantially reduced.

The reflection at the end of the optical fiber waveguide is eliminated by eliminating the reflection there, i.e., by adding an optical blooming coat to the end of the optical fiber waveguide
It is known to suppress by adding at). However, this method is time consuming and expensive.

Also, many laboratories do not have the equipment to perform this method.

OBJECT OF THE INVENTION The object of the invention is to provide a low reflection line termination which has a simple structure but effectively reduces reflection effects.

<Summary of the Invention> According to one embodiment of the present invention, a glass disk provided at the end of the line has its non-coated surface in contact with the end surface of the optical fiber waveguide, and the other surface is coated with a blooming coat. is carried. To prevent unwanted reflections from occurring at the transition between the optical fiber waveguide and the glass disk, the glass disk has the same reflectivity as the optical fiber waveguide.

Applying a blooming coat to a glass disk is much easier than directly attenuating a fiber optic waveguide. Additionally, the glass disc removably mounted at the end of the line can be removed and polished if necessary, ensuring that any distortion of the measurement results due to contamination is completely eliminated when used in conjunction with the line measuring device. The end face of the optical fiber waveguide, which can be avoided, is pressed against the glass disk by the spring, so that a complete contact is formed between the optical fiber waveguide and the glass disk.

The end of the optical fiber waveguide is designed in the form of a resilient plug pin which extends through the guide sleeve to the glass disc with a resilient bearing element that supports the glass disc against the guide sleeve.

The holder, which can be connected to the guide sleeve, pushes the glass disk from the outside towards a bearing element, preferably in the form of an O-ring, so that the glass disk is fixed in a slightly remote position from the guide sleeve. This configuration ensures optimum contact between the end face of the plug bottle and the glass disk.

This type of low reflection termination is particularly suitable for measurement configurations where it can be used as a low reflection adapter between a fiber optic waveguide and a power meter. The typical reflectance at the end of an optical fiber waveguide, which typically amounts to 4%, can be reduced to less than 0.2% by the line termination design according to the present invention.

Embodiment of the Invention The line termination shown in FIG. There is. The end face 4 of the glass fiber 3 carries a glass disc 5 whose outward output face is provided with a blooming coat 6 . The holder 7 screwed onto the guide sleeve 1 has a bearing element 8 designed as an O-ring.
Push the glass disc 5 towards it and fix it in place.

The plug bin 2 is connected to an annular flange 9 which serves as a bearing for one end of the pressure spring 10. The other end of the pressure spring 10 presses against the inside of the cap screw 11, which is shown in dotted lines in the drawing. The internal thread 12 of the cap screw 11 threads onto the guide sleeve, so that the plug bottle 2 and thus the end face 4 of the glass fiber 3 are pressed against the glass disk 5 in the direction indicated by arrow a. By pressing the end face 4 against the glass disk 5 with the force exerted by the spring 10, a complete contact is created between the glass fiber 3 and the glass disk 50.

The holder 7, which can be mounted by means of a thread 13, is provided with a central passage aperture 14 for the light beam 15. The holder 7 can be removed from the guide sleeve 1 in order to remove and clean the glass disk 5.

The effect of the low reflection line termination is due to the fact that the materials that touch each other at the contact point between the glass fiber 3 and the glass disk 5 have the same light reflectivity, so that no reflection occurs there. . The reflection level occurring in the blooming coat 6 is very low depending on the quality of the coat. This results in a low reflectivity of the overall structure. Therefore, the reflectance at the end of the glass fiber can be easily reduced to 0.2% or less.

For use in low reflection line termination, the glass fiber plug is screwed onto the guide sleeve by means of a cap screw 11. The holder 7 can be screwed onto the measuring head if power measurements are to be carried out. In order to explain the principle of the elastic plug pin 2, a flange 9 and a spring 10 are used.
and the cap screw 11 is shown in simple form.

The arrangement according to the invention offers the advantage that the reproducibility of optical line measurements is improved. One application in which this arrangement can be advantageously used is the measurement of forward and backward directed waves using optical waveguides. FIG. 2 illustrates the measurement of the reflectance of a glass fiber component, such as an optical attenuator 16. The optical transmic 17 is connected to the attenuator 16 to be measured via a waveguide coupler 18. This connection takes place via line branch 19.20.

The remaining two line branches are 21.22 are waveguide couplers 1
8 to two optical power meters 23,24. Adapters 25,26 are line terminations according to the invention.

The operation of waveguide coupler 18 is as follows.

The power present in line branch 22 is
is proportional to the power directed toward the measurement object 16.

Therefore, no power contribution occurs to the line branch 21. The direction of the applied power is indicated by arrow 11, arrow 2, and R3.

Similarly, the power in line branch 21 is proportional to the power reflected by measurement object 16. There must not be any power contribution to line branch 22 due to reflected power.

For this measurement it is crucial that the power meters 23,24 are equipped with low reflection terminations. For example, if a reflection occurs in the power meter 24, the measurement results obtained in the line branch 2I will necessarily be distorted. The power reflected by the measurement object 16 is indicated by the arrow R1.
further divided between line branches 19.21 indicated by arrows R2 and R3.

<Effects of the Invention> As is clear from the above-mentioned embodiment of the present invention, by implementing the present invention, reflection at the optical line termination is small and
Moreover, since it is easy to handle, it is easy to reduce the influence of return light caused by optical measurement. Therefore, the present invention is useful in practical use.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the low reflection line termination of the present invention. FIG. 2 is an organization diagram of a measurement system using a waveguide coupler. ■ = guide sleeve; 2 nib lug pin; 3 nib glass fiber; 4 end face of nib glass fiber 3; 5 nib glass disc; 6: blooming coat; 7: holder; 8:
Bearing element; 9: annular 7 lange; 10: pressure spring; 11: camp screw; 12, 13: screw. Applicant Yokogawa Huylett Packard Co., Ltd. Agent Patent Attorney Tsuguo HasegawaFIG, 1

Claims (1)

[Claims] The end face (4) of the optical fiber waveguide (3) at the line terminal
) is brought into contact with a glass plate (5) having the same optical refractive index as the optical fiber waveguide (3), and a pluming coat is applied to the output end face of the glass plate (5) that is far from the optical fiber waveguide. (6) Low reflection line termination.