JPS647022B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for metallizing the surface of an optical fiber by sputtering.

For the purpose of improving the mechanical strength, heat resistance, etc. of optical fibers, the use of metal coatings instead of plastic coatings has already been implemented, and the effectiveness of sputtering as a metal coating method in this case has also been studied. However, the problem remains.

For example, in known sputtering, cations are collided with a metal target (cathode) by gas discharge in an atmosphere with a predetermined degree of vacuum, and the target atoms are ejected to the anode side to form a mist from the target. By generating metal and interposing a desired deposit between the target and the anode,
A mist of metal was deposited on the surface of the deposit, but in such cases, the directivity of the mist of metal was fixed in only one direction, from the target to the anode. When the deposit is an optical fiber, a thick metal coating is formed only on a part of the outer periphery of the optical fiber, and the remaining part is hardly coated with metal, which is an undesirable result. Ta.

In addition, the conventional atmospheric vacuum degree is, for example, 10 ^-2 ~
Since sputtering was performed in a room at 10 ^-4 torr with residual gas replaced with Ar, Kr, and Xe, the target and optical fiber were exposed to plasma, which caused the problem that the optical fiber was easily affected by temperature.

Furthermore, due to the low degree of vacuum, there were problems in that the coating on the optical fiber could absorb gases such as Ar, and was susceptible to contamination from the walls of the sputter chamber.

This invention focuses on the above-mentioned problem, and the optical fiber after spinning is guided into a high vacuum chamber in a rotating state, and the ion beam from the ion source is directed to a target placed at a predetermined reflection angle provided in the vacuum chamber. The present invention proposes a method for coating an optical fiber with a metal by irradiating the target with spatter particles and depositing spatter particles on the optical fiber.

Embodiments of the invention will be described below with reference to the drawings.

FIG. 1 is a partially longitudinal front view of a metal coating apparatus for carrying out the method of the present invention, in which 1 is a sputtering tank as a vacuum chamber, which is constantly evacuated by a vacuum pump, for example 10 ^-5 ~ It is maintained at a high vacuum level of 10 ^-6 torr.

2 is a spinning furnace of a spinning device installed above the sputtering tank 1, and 3 is a preform of a glass rod consisting of a core and a cladding made by a CVD method, etc., which is heated above its softening point in the spinning furnace 2 and then heated outside. The optical fiber 4 of desired size is continuously obtained by drawing down the diameter.

Optical fiber 4 obtained continuously in this way
is subjected to the metal coating treatment described later, and then sputtered in the sputtering tank 1.
It is led out and wound up on the winding drum 5.

Reference numeral 6 denotes an ion source attached to the sputtering tank 1, which projects the ion beam B generated by this ion source toward the lower part of the sputtering tank 1.

In the projection direction of the ion beam, a target 7 facing the optical fiber 4 at an angle of 45° is arranged, for example, and this target 7 receives the ion beam and causes spatter particles S to adhere to the optical fiber 4.

Note that 8 is a metal-coated optical fiber coated with metal with sputter particles S.

The preform 3, the spinning furnace 2 and the winding drum 5
are installed on turntables that rotate at a constant speed, and these turntables are driven by a motor at a predetermined rotational speed.

In the embodiment of the present invention, the optical fiber 4 molten is drawn down from the spinning furnace 2 and is wound up by the winding drum 5 so as to hang straight. When the ion beam B passes through the target 7
spatter particles from the fibers adhere to the optical fiber 4.

Since the optical fiber 4 is rotating at this time, the metal particles are thinly and evenly coated on the circumferential surface of the optical fiber 4, and the desired metal-coated optical fiber 8 is obtained.

According to this implementation method, since the optical fiber 4 and the target 7 are not placed in the plasma, the optical fiber 4 is not exposed to high temperatures and deteriorates, and the vacuum pressure inside the sputtering tank 1 is high. , there is no possibility of unnecessary gas molecules being mixed into the spatter particles, and the purity of the metal coating is increased.

FIG. 2 shows another embodiment of the target 7 in this invention.

This target 7a is made of an arcuate (or semicircular) metal plate that surrounds the optical fiber 4, and the metal plate surface of this target 7a is at an angle of, for example, 45° with respect to the optical fiber 4 at any position. are facing each other.

If the method of the present invention is carried out using this target 7a, the amount of sputtered particles S attached to the optical fiber 4 will be increased, and the efficiency of the coating operation will be improved.

Next, embodiments of the present invention will be described in more detail.

Now, using Kaufmann type ion source 6, approximately
300 ion beams are extracted, with an ion current density of 1±0.82 mA/cm ² and an ion beam acceleration voltage of 2 KV.

The vacuum pressure in the sputtering tank 1 was set at 10 ^-5 to 10 ^-6 torr, and the target 7a was made of Al, Cu, In, Ti, Ni, etc., and the optical fiber 4 was rotated at 5 to 8 rpm. A metal film of equal thickness was formed with a thickness of 50 to 100 Å.

As another specific embodiment of this invention, vacuum pressure
At 10 ^-5 to ^{10 -6} torr, _the target _was Al,
When an ion beam of 99.99% high purity Ar as Si, Ti, etc. was accelerated at 3KV, an extremely dense thin film was formed on the optical fiber 4.

In this case, electrolytic plating or the like may be applied on this thin film in order to increase the film thickness.

As explained above, the present invention introduces a spun optical fiber, which is rotating around the optical fiber axis, into a vacuum chamber, and in the vacuum chamber, targets having a sputter particle irradiation angle in a direction intersecting the optical fiber axis. In this optical fiber metal coating method, an ion beam guided into the vacuum chamber from an ion source is irradiated, and spatter particles generated from the target are deposited on the outer periphery of the optical fiber. It is an arc-shaped metal plate that surrounds the fiber, and is characterized by an included angle of 45° between the spatter particle generation surface and the optical fiber.

In the method of this invention characterized by such a configuration,
Unlike conventional methods, the optical fiber does not suffer from deterioration of its characteristics due to exposure to plasma, and the metal coating on the optical fiber can be made thin and uniform, and
By not allowing the metal coating to absorb gas impurities, not only can the purity of the metal coating be increased, but also the following effects can be obtained.

That is, in the case of the present invention, when coating an optical fiber with metal by sputtering means, the target is an arc-shaped metal plate surrounding the optical fiber, and the included angle between the spatter particle generation surface and the optical fiber is
Since it is set at 45 degrees, the spatter particles are intensively irradiated from the periphery of the optical fiber toward its outer periphery and perpendicular to the optical fiber axis.
Therefore, the amount of metal deposited on the optical fiber is dramatically improved, and the metal coating work itself can be performed efficiently.

[Brief explanation of drawings]

FIG. 1 is a partially longitudinal front view of a metal coating apparatus showing the method of the present invention, and FIG. 2 is a perspective view showing another embodiment of the target. 1... Sputter tank (vacuum chamber), 4... Optical fiber, 6... Ion source, 7, 7a... Target.

Claims (1)

[Claims] 1. The spun optical fiber, which is rotating around the optical fiber axis, is introduced into a vacuum chamber, and in the vacuum chamber, a target having a sputter particle irradiation angle in a direction that crosses the optical fiber axis is In a metal coating method for an optical fiber, in which an ion beam guided into a room is irradiated and spatter particles generated from a target are coated on the outer periphery of the optical fiber, the target is formed in an arc shape surrounding the optical fiber. A method for coating an optical fiber with metal, characterized in that the included angle between the spatter particle generation surface and the optical fiber is 45°.