JPH0422906A - Production of rare earth element-added waveguide - Google Patents

Abstract

PURPOSE:To form the glass waveguide of a low loss by constituting tablets of lumps of >=10mum particles at the time of forming films on substrate surfaces by irradiating the tablets with electron beams. CONSTITUTION:The tablets 9, 10 consisting of the lumps of the particles contg. rare earth elements and SiO2 and having >=90% sintering density and >=10mum grain size are heat treated at the temp. slightly lower than the m.p. The sintering density is, therefore, increased and the tablets 9, 10 consisting of the lumps of at least 10mum particles are obtd. Since the tablets 9, 10 consist of the lumps of >=10mum particles, the simultaneous splashing of the particles around the irradiated parts does not arise at the time of forming the films 11 on the substrate 5 surfaces by irradiating the tablets 9, 10 with the electron beams. The glass films 11 for cores without contg. the fine particles of several mum are thus formed. The flush type waveguide of the low loss is thus formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a low-loss glass waveguide doped with rare earth elements.

E. Prior Art] In recent years, research into optical fiber amplifiers and lasers in which the core of the optical fiber is doped with rare earth elements has become active, and amplifiers and lasers for light wave communications are attracting attention. Along with this, there are also plans to add rare earth elements to the core portion, which is the light propagation portion, of the glass waveguide to construct lasers, amplifiers, or various optical circuits with amplification functions.

The present inventor proposes the following method as a method for manufacturing a glass waveguide doped with rare earth elements.

This method involves forming a core glass film containing a rare earth element on a substrate having a low refractive index layer using an electron beam evaporation device, and then processing the core by high-temperature heat treatment, photolithography, and dry etching. A buried glass waveguide is manufactured through a refractive index glass film coating process, and is particularly characterized by the method of forming the core glass film.

The method includes rare earth elements, refractive index controlling oxides and 5i
After mixing the n2 powder and hardening it with a hot press, it is further sintered to form a granular, plate-shaped, or rod-shaped tablet,
In this method, this tablet is evaporated using high vacuum oxygen partial pressure using an electron beam evaporation device to form a glass film for the core.

Here, the rare earth elements are Er, Nd, Yb, Ce, H
Oxide containing at least one kind of oxide, Tm, etc., and the refractive index controlling oxide is P, Ge, Ti, AI, Zn,
Refers to an oxide containing at least one type of B, F, etc.

[Problems to be Solved by the Invention] However, in the above manufacturing method, as a result of observing a dark field image with an R microscope, fine particles with a particle size of several μm were found in the core glass film as shown in FIG. was found to be mixed in.

When we investigated the cause of this, we found that the tablet is made of a sintered body of fine particles of several micrometers in size, as shown in Figure 5. When the tablet is irradiated with an electron beam, the irradiated part melts and becomes evaporated atoms, forming a film on the substrate surface. However, it was revealed that fine particles around the irradiated area were scattered at the same time and mixed into the core glass film.

When a glass waveguide is created using such a core glass film, it becomes a glass waveguide with large scattering loss, and many countries are now using it to realize lasers, amplifiers, and the like.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a rare earth element-doped waveguide that can solve the above problems and manufacture a glass waveguide with low loss.

"Means for Solving the Problems" In order to achieve the above object, the method for manufacturing a rare earth element-doped waveguide according to the present invention includes a rare earth element and SiO2, a sintered density of 90% or more, and a grain size of S containing rare earth elements is deposited on a substrate having a low refractive index layer by evaporating a tablet consisting of agglomerates of particles of 10 μm or more using an electron beam evaporation method.
io, a step of heat-treating the entire substrate at a high temperature, a step of processing the core glass film into a core having a substantially rectangular cross section by photolithography and dry etching, and a step of forming a core glass film on the substrate. The process consists of a step of coating the entire core with a glass film having a low refractive index.

5 Effect] According to this manufacturing method, when the tablet is irradiated with an electron beam to form a film on the substrate surface, the tablet has a thickness of 10 μm.
Since it is made up of agglomerates of particles larger than m, particles around the irradiated area will not be scattered at the same time, making it possible to form a core glass film that does not contain fine particles, creating a low-loss glass waveguide. can do.

``Example'' Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

(Embodiment 1) FIG. 1 shows an electron beam evaporation apparatus 1 for carrying out the first step. Evaporation sources 4a and 4b are arranged, and a concave substrate holder 6 for holding a plurality of substrates 5 is arranged above. Further, a supply gas system 7 for supplying oxygen gas and a vacuum exhaust system 8 for evacuating the inside of the housing 2 are connected to the housing 2 . One evaporation source 4a accommodates a tablet 9 containing a mixture of SiO□ and Ti0z, and the other evaporation source 4b accommodates a tablet 10 of E r 20 s.

The former tablet 9 is made by mixing 1% TiO□ powder into SiO□ powder with a weight ratio of 99%, and heating it at 1000°C.
The sintering density is said to be 90% by hot pressing at a temperature of .

As shown in Figure 5, the tablet in this state is a sintered body made up of agglomerates of fine particles of several micrometers in size.
By heat-treating at a temperature of 0° C., a sintered tablet consisting of agglomerates of particles several tens of micrometers in size is obtained, as shown in FIG. The latter tablet 10 is similarly heat-treated at a temperature slightly lower than the melting point so as to form a sintered body consisting of agglomerates of particles several tens of micrometers in size. As the substrate 5 having the low refractive index layer, quartz glass with a diameter of 3 inches and a thickness of 1 mm is used.

Then, oxygen gas is supplied inside the housing 2 under a high vacuum state of 10-' Torr so that the degree of vacuum becomes 5 x 10-' Torr, and in this state, the tablets in the evaporation sources 4a and 4b are By simultaneously irradiating 9.10 with an electron beam, the core glass W of SiO□-TiO□ containing Er ions on the surface of the substrate 5! A11 (see FIG. 2(a)), in this case, the core glass If! In order to control the amount of Er ions added to the Er2O3 tablet 10, it is sufficient to control the t current value of the electron beam irradiated to the Er2O3 tablet 10, and by this control method, the amount of Er ions added can be adjusted from several ppm to several percent. Next, the entire substrate 5 on which the core glass film 11 is formed is subjected to high-temperature heat treatment at a temperature of 1000° C. or higher to form a dense film with a wavelength of 0.63 μm and a refractive index of 1.4651. 11 (b), then a WSf film 12 with a thickness of 1 μm is formed on the surface of the above-mentioned 1111 by sputtering (FIG. 2(c)), and the WSi! A photoresist is applied to the surface of the film 112, the photoresist film 13 is patterned by photolithography (d), and dry etching is performed using NFs gas.
2. Perform patterning (e). Next, Photoresist II! 13 and W Si H 12 as masks, the core glass film 11 is patterned by dry etching using CHF s residue (f) to form the core 14.

Next, after removing the photoresist film 13 and W S i H 12 (g), SfO with a refractive index of 1.4580 (value at a wavelength of 0.63 μm) is deposited over the entire core 14 on the substrate 5.
A buried waveguide is completed by covering with □-P20sB20s glass 11115 (h).

According to this manufacturing method, in particular, since the tablets 9 and 10 are heat-treated at a temperature slightly lower than their melting point, the sintered density can be increased, and tablets 9 and 10 consisting of agglomerates of particles of at least 10 μm can be obtained. can. Therefore,
When forming the film 11 on the surface of the substrate 5 by irradiating the tablets 9 and 10 with an electron beam, the tablets 9 and 10 have a thickness of 10 μm.
Since it is made up of agglomerates of the above particles, particles around the irradiated area will not be scattered at the same time, and the core glass film 11 will not be contaminated with fine particles of several μm as shown in Fig. 4.
can be formed, making it possible to create a low-loss buried waveguide.

The absorption loss due to other than Er ions in this waveguide is 0.1d
B/cm or less. In addition, almost no unevenness in the waveguide distribution, which is the center of scattering, was observed.

The absorption loss in the 1.53 μm band due to E, r ions is E
Depending on the amount of r added, it was possible to achieve a value of several dB to more than ten dB. Therefore, with this waveguide, 1.53μm
By superimposing and propagating the band signal light and the 0°098 μm or 1.46 μm pump light, it is possible to amplify the 1.53 μm band signal light.

(Example 2) In the above-mentioned Example 1, a two-source evaporation method using two evaporation sources 4a and 4b was adopted, but in this example, a tablet was put in only one evaporation source 4a and a single-source evaporation method was used. A core glass film 11 of SiO□-Ge02P2O5 doped with ions was formed on the surface of the substrate 5. As a tablet, a soot-like fiber core matrix (SiOs and GeO
A fiber core base material (diameter 15 mm, wavelength 0.63
Refractive index in μm 1.4620, amount of Er ions added 30
As a result, a core glass film 11 of S S Ox G e O2P 20 s having a uniform addition amount of Er ions of approximately 1800 ppm could be formed on the substrate 5 to a thickness of 7 μm. The refractive index of this core glass film 11 is 0.6 at wavelength.
It was 1.4612 at 3 μm. Then, as a result of creating a buried waveguide using the substrate 5 having this core glass film 11 in the same manner as in Example 1, a waveguide with extremely low scattering loss could be obtained.

(Example 3) In this example, as in Example 2 above, E
A core glass WA11 of 5102 TiO□ doped with r ions was formed on the substrate 5.

The tablet used in this case was formed as follows. First, the weight ratio of SiO2 and T t O2 powders was 99.
They are mixed at a ratio of 1:1, hot pressed at 100°C, and then heat treated at a temperature of 1500°C to obtain tablets. After soaking this tablet in Fuchu for 24 hours, in which 0.5 Q of E r C]s was dissolved in anhydrous alcohol solution,
By dry casting in an atmosphere of 0□ and He and heat-treating again at a temperature of 1700°C, the sintered density was 93% and 100 μm.
It was made into a sintered body tablet consisting of a mass of particles of about 100 mL.

Even when this tablet is used, the core glass pi! formed on the substrate 5! No fine particles of several μm were mixed in the core glass 1111, which was transparent and homogeneous, and a waveguide with low loss could be created. Note that the amount of Er ions added into the core glass film 11 was about 2000 ppm.

(Example 4) In this example, as in Example 2, S i O2T f O2 to which Er ions and F ions were added by the single-source evaporation method was used.
A core glass film 11 was formed on the substrate 5 to a thickness of 7 μm. The tablet used in this case was formed as follows. First, S i O2, T i O2 and ErFz
The powders were mixed at a weight ratio of 89:1:10, hot pressed at 1000°C, and then heat treated at 1700°C to achieve a sintered density of 90% or more and 100 μm.
It was made into a sintered body tablet consisting of a mass of particles of about 100 mL.

By using this tablet, it is possible to obtain a core glass film 11 of 5iO2-TM01 doped with approximately 500 ppm of Er ions and F ions without the inclusion of fine particles that become scattering centers, and to create a low-loss waveguide. I was able to create it.

(Example 5) In this example, Er-
S i O2T i O doped with Nd and F ions
Core glass M11 of t was formed on the substrate 5 to a thickness of 1 μm. In this case, as a tablet, 5to2, Ti
12, ErFz and NdF powder at a weight ratio of 85:1:
They were mixed at a ratio of 10:4 and heat treated in the same manner as in Example 4.

The thus created waveguide doped with Er, Nd, and F ions can be expected to be used in amplifiers in the wavelength band of 1.3 μm and 1.5 μm.

Note that the present invention is not limited to the above embodiments,
For example, in addition to Er and Nd, rare earth elements include Yb and Ce.
, Ho, Tm, etc. may be used, and P, Ge, Ti-A1. An oxide containing at least one type of Zn, B-F, etc. may be used.

[Effects of the Invention] In summary, according to the present invention, when forming a film on the substrate surface by irradiating the tablet with an electron beam, the tablet
Since the lick is made up of agglomerates of particles of 0 μm or larger, particles around the irradiated area will not be scattered at the same time, making it possible to form a glass film for the core that does not contain fine particles, creating a glass waveguide with low loss. can do.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an electron beam evaporation apparatus used in the method for manufacturing a rare earth element-doped waveguide according to the present invention;
Fig. 2 is a diagram showing the steps of the same manufacturing method, Fig. 3 is a diagram showing the surface structure of the tab left used in the same manufacturing method, and Fig. 4 is a diagram showing the surface structure of the tab left used in the same manufacturing method.
The figure shows the surface structure of a core glass film produced by the production method previously proposed by the present inventor, and FIG. 5 shows the surface structure of Taplet-Soto used in the same production method. In the figure, 1 is an electron beam evaporation system! , 4a, 4b are evaporation sources,
5 is a substrate, 9.10 is a tablet, 11 is a glass film for core, 14 is a core, and 15 is a glass film.

Claims (1)

[Claims] 1. Contains rare earth elements and SiO_2, and has a sintered density of 90
% or more and a particle size of 10 μm or more by electron beam evaporation to form a core glass film of SiO_2 containing a rare earth element on a substrate having a low refractive index layer; a step of heat-treating the entire substrate at a high temperature; a step of processing the core glass film into a core having a substantially rectangular cross section by photolithography and dry etching; and a step of coating the entire core on the substrate with a glass film with a low refractive index. A method for manufacturing a rare earth element-doped waveguide comprising: 2. The method for manufacturing a rare earth element-doped waveguide according to claim 1, wherein the tablet is composed of a rare earth element-containing tablet and a SiO_2-containing tablet, and these tablets are evaporated from separate evaporation sources. 3. The method for manufacturing a rare earth element-doped waveguide according to claim 1, wherein the tablet contains at least two types of rare earth elements. 4. The method for manufacturing a rare earth element-doped waveguide according to claim 1, wherein the tablet is vitrified. 5. The method for manufacturing a rare earth element-doped waveguide according to claim 1, wherein the tablet contains F. 6. The method for manufacturing a rare earth element-doped waveguide according to claim 1, wherein the tablet is formed by impregnating a porous tablet with a liquid containing a rare earth element, drying it, and subjecting it to high-temperature heat treatment. 7. The method of manufacturing a rare earth element-doped waveguide according to claim 1, wherein the tablet is formed by mixing raw material powders and baking and solidifying the mixture using a hot press.