JPH0353202A - Production of waveguide added with rare earth element - Google Patents

Abstract

PURPOSE:To provide the smaller size, lower loss and multi function by adding a rare earth element with good controllability to a core waveguide which is the light propagating part of the glass waveguide having a planar structure. CONSTITUTION:A glass filter 3 for the core contg. the rare earth element is formed by using an electron beam vapor deposition device on a substrate 1 on which a buffer layer 2 having a low refractive index is formed. The substrate is thereafter heat-treated at a high temp. A metal 4 is then formed on the core glass film 3 by a sputtering device and thereafter, a photoresist film 5 is applied on the metal film 4 and is subjected to photolithography and dry etching to pattern the core glass film 3. The photoresist film 5 and the metal film 4 are removed and the entire part of the core glass waveguide 3 is coated with a clad film 6. The rare earth element is added with the good controllability into the core of the glass waveguide having the planar structure. Thus, the optical device having the small size, the low loss and the multi function is obtd.

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to a method for manufacturing a glass waveguide doped with rare earth elements. [Prior art] An optical fiber doped with rare earth elements in the core of an optical fiber. Research into fiber amplifiers and racers began to be actively conducted.
It has started to attract attention as an amplifier and laser for light wave communication.

Conventionally, as shown in FIG. 71, as an optical fiber amplifier,
By propagating the signal light in the optical fiber 20 doped with the rare earth element Er, and combining the excitation light with respect to the propagation direction of the signal light using the optical fiber coupler 21 to form a population inversion state, A method of amplifying the signal light and separating the pumping light from the output side with an optical fiber coupler 22 is being considered (Kimura, Nakazawa: Oscillation characteristics of optical fiber lasers and their application to optical communications, Laser Society Research Group, RTH
-87-16.1)l). 31-37. 1988 1
Month}.

[Problems to be solved by the invention] The optical fiber amplifier and laser have (1) a core diameter of 10
Due to its small diameter of about μ, the pumping power density increases and the pumping efficiency increases; (2) the interaction length can be long; and (3) in the case of silica-based optical fibers, the loss is extremely low. , and other characteristics. However, semiconductor lasers. Photodetector, optical modulation circuit, optical branching/coupling circuit.
When trying to configure a system in which optical switching circuits, optical multiplexing/demultiplexing circuits, etc. are mounted, there is a problem that it is difficult to downsize and reduce loss because each is an individual component. In addition, since the optical axis of each individual component must be adjusted and placed individually, it takes a huge amount of adjustment time and increases costs. There were also issues such as reliability issues.

The purpose of the present invention is to solve the problems of the prior art described above,
Small size. In order to achieve low loss and multifunctionality, we provide a method for manufacturing a glass waveguide that allows rare earth elements to be added with good control to the core waveguide, which is the optical propagation part of a glass waveguide with a planar structure. [Means for Solving the Problems] The method for manufacturing a rare earth element-doped waveguide of the present invention consists of the following processes (a) to (d).

(a) Rare earth element, oxide for controlling refractive index, S i 02
A process of mixing powders of and evaporating the solidified tablenot by electron beam evaporation to form a glass film of the mixture on a substrate having a low refractive index layer; (b) a process of heat-treating the substrate at a high temperature; (c) A process of processing the glass film into a substantially rectangular shape by photolithography and dry etching processes; (d) A process of coating the entire surface of the processed film with a glass film having a low refractive index.

As the rare earth element, an oxide of a rare earth element or a rare earth element containing F can be used, and
Two or more types of the above rare earth elements may be included.

[Function] Rare earth elements are added to the core portion of the glass waveguide, which is the light propagation portion, to generate a laser beam. When implementing the amplifier 1 or various optical circuits with an amplification function, the output of pumping light. When the waveguide length is fixed, it is necessary to control the amount of rare earth elements added. However, a manufacturing method for adding rare earth elements into a glass waveguide in a well-controlled manner has not yet been reported.

In the present invention, a core glass film containing a rare earth element is formed on a substrate on which a low refractive index layer is formed using an electron beam evaporation apparatus, and then subjected to high temperature aging treatment. This is a method of manufacturing a glass waveguide using photolithography, dry etching, and a process using a low refractive index glass film, and is particularly characterized by the shape and method of the glass film for the core. That is, rare earth elements,
The refractive index controlling oxide and SiO2 powder are mixed, hardened using a hot press, etc., and then sintered to form a granular, plate-like, or rod-like tablet.
For example, 10-'~10-410'r
In this method, the glass film for the core is formed by evaporation in an oxygen atmosphere in an electron beam evaporator. Here, the rare earth elements include erbium Er, neodymium Nd, eveterbium Yb, cerium Ce. A substance containing at least one of 17 elements such as holmium Ho and thulium Tn+. In addition, as an oxide for controlling the refractive index,
An oxide containing at least one of phosphorus P, germanium Ge, titanium T+, aluminum Aj, zinc Zn, boron B, fluorine F, etc. [Example] FIG. 1 shows an example of the method for manufacturing a rare earth element-doped waveguide of the present invention. Figures (a) to (11) show the steps of the manufacturing method.

First, as shown in (a), a buffer layer 2 (refractive index Nb, for example Si02. , P, Ti, Ge, F, AJJsn, etc.) is formed to a thickness of several microns to several tens of microns.

Next, as shown in (b), a core glass WA3 of several μm to 10 μm is formed on the buffer layer 2, and then
The substrate is heat-treated at a high temperature of around .degree.C.

Here, the core glass film 3 is formed by an electron beam evaporation method as shown in FIG. That is, the electron beam evaporation device 7 is kept in a high vacuum by the vacuum evacuation system l1.
An evaporation source 9 is provided inside the evaporation source 9, and a tablet 10 is placed inside the evaporation source 9.
This tablet 10 contains at least rare earth elements. A core glass film that is made by mixing powder of SiO2, an oxide for controlling the refractive index, hardening it with a bottle press, and then sintering it to form a tablet in the shape of a granule, plate, or rod. The amount of rare earth element to be added to #3 can be controlled at the stage of preparing the powdered material. Further, the refractive index nW (nw>nb) of the core glass film 3 is also changed to oxidation #'lJ (Ti
, Ge, P, AJI, Zn, SnB,F
This can be controlled by adjusting the amount of oxides containing at least one type of oxide.

In FIG. 2, a substrate holder 8 is provided above the tablet 10, and ten or more substrates (with buffer layer 2) (2) are attached to this holder 8. The substrate 1 is heated to about 300 to 350° C. by a heating device (not shown) provided on the top of the substrate holder 8. Oxygen gas 12 is then fed into the electron beam evaporator 7 maintained at a high vacuum, and while maintaining a vacuum level of 10-3 to 10-' Torr, the tablet 10 in evaporation #9 is exposed to an electron beam (not shown). In this method, the core crow PIA 3 is formed on the entire surface of the buffer layer 2 of the substrate 1.

FIG. 3 shows an example of the characteristics of the core glass film produced by the method shown in FIG. 2 above. This is as Tablet 10,
Results of analyzing the concentration of Er added to the core glass vAB when the core glass film 3 was formed using a mixture of powders of S+ 02 , T+ 02 , and Er203 and varying the amount of Er203 added. It is. Er203
This shows that it is possible to control the addition concentration of E' with respect to the amount of preparation. From this result, the target is created using FI Pa.
It can be seen that by adjusting the amount of Er203 in advance, the amount of Er added to the core glass M3 can be controlled.
Next, as shown in FIG. 1(c), a metal 4 (for example, WSilg!) is formed on the core glass film 3 using a sputtering device. After that, apply the bottom resist film 5 on the metal v4,
After one rebake, a glass mask with a desired pattern formed thereon is placed, and ultraviolet rays are irradiated from above to pattern the photoresist film (photolithography method in (d)).

Next, as shown in (0), photoresist v. 5 as a mask, the metal film 4 is patterned by dry etching, and then, as shown in (f), the photoresist film 5. Using the metal film 11 as a mask, the core glass 1 and 3 are patterned by dry etching.

Next, as shown in (g), after removing the photoresist film 5 and the metal film 4, the entire core glass waveguide 3 is covered with a cladding film 6 (refractive index nC, nc < n1v) (Nh). The method described above is for manufacturing a buried-type glass waveguide.

The method for manufacturing a rare earth element-doped birch wave path of the present invention is not limited to the above-mentioned embodiments. For example, it can be applied to waveguides of lintel type, embankment type, loaded type, etc. In addition, as rare earth elements, in addition to oxides such as the above Er203,
The use of rare earth elements containing F, such as Er F3 and Nd F3, is effective when adding a large amount of rare earth elements. In other words, adding a large amount of rare earth elements increases the refractive index of the core glass film, but if F is also added at the same time, F
There is Mellin l-, which has the role of lowering the refractive index, so there is no need to take the trouble to add an oxide for controlling the refractive index.

Note that in the manufacturing method shown in FIG. 1, when an 8102 substrate is used as the substrate 1, the low refractive index N2 does not need to be formed.

Furthermore, in the core glass film forming method shown in FIG. 2, if another evaporation source 9 is provided to evaporate the same set of tablets at the same time, the film formation can be carried out in a shorter time. , is an effective method.

Furthermore, the fluorescent properties can be improved by mixing at least 2N of rare earth elements in a powdered state with Si02 and an oxide for controlling the refractive index. For example, Er203, Yb203, P2 05
, tablets made by mixing powders of Si02, Nd
Tablet made by mixing powders of 203, Yb203, T+ 02, Si 02, F, r F3,
Nd203, Cr203, P205, Si
Tablets made by mixing the powder of No. 02 can be used.

By using the rare earth element-doped waveguide produced by the manufacturing method of the present invention, various optical devices can be realized. Examples include lasers, amplifiers, optical star couplers with amplification functions, optical multiplexers/demultiplexers, optical switches, and even optical functional devices that combine the various optical devices mentioned above. [Effects of the Invention] As described above, the present invention mixes a rare earth element, an additive for controlling the refractive index, and SiO2 powder, hardens it by hot pressing, and then sinters it into a tablet by electron beam evaporation. By using the method of evaporating with an apparatus, it is possible to add rare earth elements into the core of the glass waveguide made of Brehner with good controllability. As a result, it is small. Low loss. Optical devices with multifunctionality can be realized.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the method for manufacturing a rare earth element-doped waveguide of the present invention, FIG. 2 is a diagram showing an example of the method for manufacturing a rare earth element-doped core glass film of the present invention, and FIG. A diagram showing an example of the control result of the rare earth element doping concentration obtained using the method shown in FIG. 2, and FIG. 4 is a schematic diagram of a conventional optical fiber amplifier. In the figure, 1 is a substrate, 2 is a buffer layer, 3 is a core glass film,
4 is a metal film, 5 is a photoresist film, 6 is a cladding film,
7 is an electron beam evaporator, 8 is a substrate holder, 9 is an evaporation source, 10 is a tablet, and 12 is oxygen gas.

Claims (1)

[Claims] 1. A method for manufacturing a rare earth element-doped waveguide comprising the following processes (a) to (d) (a) Mix powders of a rare earth element, an oxide for controlling the refractive index, and SiO2 to form a solid (b) a process of heat-treating the substrate at a high temperature; (c) photolithography, drying; (d) a process of processing the glass film into a substantially rectangular shape by an etching process; (d) a process of covering the entire surface of the processed film with a glass film having a low refractive index. 2. The method for manufacturing a rare earth element-doped waveguide according to claim 1, wherein an oxide of a rare earth element is used as the rare earth element. 3. The method for manufacturing a rare earth element-doped waveguide according to claim 1, wherein a rare earth element containing F is used as the rare earth element. 4. The method for manufacturing a rare earth element-doped waveguide according to claim 1, wherein two or more types of rare earth elements are contained.