JPH04149412A - Rare earth element charged type optical waveguide - Google Patents

Abstract

PURPOSE:To miniaturize the optical waveguide and to attain high-efficiency optical amplification by forming a slit in the core center part of the optical transmission line of the waveguide in parallel to the optical axis and charging glass which contains a rare earth element therein. CONSTITUTION:This optical waveguide consists of a substrate 1, the core part 2 of the waveguide, a clad part 3 of SiO2, etc., and the glass part 4 doped with the rare earth element such as Er<3+>, etc. The slit is formed in the center part of the core of the optical transmission line of the waveguide in parallel to the optical axis and the glass which contains the rare earth element such as Er<3+> is charged therein. Therefore, the part wherein the rare earth element is charged is varied in width and length for the overall width and length of the core to increase or decrease the doping amount of the rare earth element in the core greatly. Consequently, the small-sized optical waveguide which is large in optional amplification quantity can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a component that performs optical amplification to compensate for optical transmission loss and loss at connection points in the transmission of optical communication cables.

(Prior Art) Most optical amplification techniques in conventional optical transmission systems are fiber type optical amplification. The characteristic of fiber-type optical amplifiers is that the core part through which light is transmitted is doped with a rare earth element such as Nd "Er", and the ions of the element are excited by excitation light, and the signal light is used as a trigger to generate the same wavelength as the signal light. The signal light is amplified by emitting the light. This fiber type optical amplifier technology has the following drawbacks.

(1) Flexibility is poor due to fiber-to-fiber connection. This is due to the fact that in optical transmission systems, if the fiber type is used, the transmission and amplification fibers must be connected one-to-one, which is impractical as an amplifier for an optical fiber cable with several thousand fibers. means.

(2) There is a limit to the amount of rare earth element doping.

The amount of amplification of a fiber type optical amplifier increases approximately in proportion to the amount of doping. Therefore, the higher the doping amount, the higher the efficiency per unit length.

However, in the method of doping the core of an optical fiber with a rare earth element, as the amount of doping increases, phenomena such as precipitation of the rare earth element and cluster generation in the core occur during core creation. Doping is difficult. Even if these phenomena are suppressed and rare earth elements are doped, there is a limit to the amount of doping in a unit volume. Therefore, in order to increase the amount of amplification, it must be compensated for by distance.

Currently, with a doping amount of about 5000 ppm, 20d
In order to obtain a gain of about B, the length of the optical fiber reaches several tens to several hundreds. If the amount of doping is increased, the length will be shortened, but the above problem will occur. This concludes the current state of fiber-type optical amplification technology.

On the other hand, waveguide type optical amplification technology has not been sufficiently studied. Current waveguides are produced by depositing silica glass on a Si wafer substrate by hydrolysis, forming a cladding layer and a core layer, and processing the deposited layer by ion etching or the like. Although it is possible to dope rare earth elements when forming the core layer using this method, similar to the fiber type, phenomena such as rare earth element precipitation and cluster generation occur, and high-density Doping cannot be expected.

(Problems to be Solved by the Invention) The present invention was made in order to solve the above-mentioned drawbacks, and provides a rare earth element-filled optical waveguide that is smaller than conventional fiber amplifiers and capable of high-efficiency optical amplification. It is about providing.

(Means for Solving the Problems) The rare earth element-filled optical waveguide of the present invention has a slit provided in the center of the core of the optical transmission path of the waveguide parallel to the optical axis, and a rare earth element such as Er Fill with glass containing.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram of an embodiment of the present invention, in which 1 is a substrate, 2 is a core portion of a waveguide, 3 is a cladding portion such as 5i02, and 4 is a glass doped with a rare earth element such as Er''. 2(a) is a plan view of one embodiment of the present invention, and FIG. 2(0)) is a sectional view taken along line AA' in FIG. 2(a).

To create this, silica glass is deposited on a Si wafer substrate by hydrolysis to form a cladding layer and a core layer, and the core layer is etched by ion etching to make it parallel to the optical axis of the optical waveguide. Then, process it into a slit shape.

The iris slit is filled with bulk glass doped with rare earth elements by the sol-gel method.

The advantage of using the sol-gel method is that since it starts from a solution, it is suitable for producing bulk glass in a slit, and also because it takes into account the advantages of low temperature production and homogeneity, which are characteristics of the sol-gel method.

With this structure, by changing the width and length of the rare earth element filling part relative to the overall width and length of the core, the amount of rare earth element doping in the core can be significantly increased or decreased. Is possible. Therefore, it is possible to form a small waveguide with an arbitrary large amount of amplification.

Furthermore, the depth of the waveguide can also be changed during fabrication depending on the amount of doping. Furthermore, if optical amplification is performed using a waveguide type, the possibility of optical switches, optical branches, etc. can be expected.

(Effects of the Invention) As explained above, the present invention makes it possible to prevent precipitation and cluster generation during rare earth element doping in conventional fiber-type fibers by performing optical amplification for optical transmission using a slit-type waveguide. Therefore, the amount of rare earth element doping can be increased, and a small optical waveguide capable of highly efficient optical amplification can be realized.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the rare earth element-filled optical waveguide of the present invention, FIG. 2(a) is a plan view of the waveguide of FIG. 1, and FIG. 2(b)
is a sectional view taken along line AA' in FIG. 2(a). 1... Waveguide substrate 2... Waveguide core part 3
...Waveguide cladding part 4 such as 5i02... Rare earth element filling part in the core Patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. A rare earth element-filled optical waveguide, characterized in that a slit is provided in the center of the core parallel to the optical axis, and the slit is filled with glass containing a rare earth element.