CN1128113C - Non-linear optical wave guide of thiohelogen glass and its preparing process by ion exchange - Google Patents

Abstract

The invention discloses a nonlinear sulfur-halide glass optical waveguide and an ion exchange preparation method thereof. The said optical waveguide is prepared by using sulfur halide glass with high trivalent nonlinear coefficient as the carrier, using special molten salt through ion exchange, and the refractive index difference Δn is 0.001-0.04. It is an excellent carrier of integrated optics in the circuit and has a very broad application prospect.

Description

Method for preparing nonlinear sulfur-halogen glass optical waveguide by ion exchange

technical field

The invention relates to a method for preparing nonlinear sulfur-halide glass optical waveguide by ion exchange.

Background technique

Optical waveguide is the carrier of fast transmission of a large number of optical signals, and also the substrate of integrated optics in micro-optical circuits. Optical waveguide has important application value in the fields of optical fiber communication, integrated optics, variable refractive index optics and optical fiber sensing. With the development of optical communication, optical computing, and optical information processing, all-optical information processing devices have attracted more and more research interest, such as: optically controlled optical switches, optical bistable devices, optical logic gates, optical amplifiers, Wavelength division multiplexers, fiber lasers, etc., many of which are based on nonlinear optical waveguides. It can be expected that photonic technology based on photonic devices will have strong competitive potential in the next stage, among which nonlinear optical waveguide devices and technologies will undoubtedly play an important role.

The optical waveguide is based on the nonlinear optical material, so the quality of the nonlinear optical material will directly affect the performance of the optical waveguide. Nonlinear optical materials are generally divided into three types: crystal materials, glass materials and polymer materials. Generally, the following formula can be used to measure the quality of materials:

W＝κ ₀ Δn'/α ₀ τ where:

W———Nonlinear Optical Material Quality Coefficient

κ ₀ ———Proportional coefficient

α ₀ ——— linear absorption coefficient

τ———response time

Δn’———Nonlinear refractive index change

It can be seen from formula (1) that the improvement of the quality factor of all-optical devices must simultaneously increase the nonlinear refractive index change Δn', decrease the linear absorption coefficient α ₀ and reduce the response time.

At present, most nonlinear optical waveguides use semiconductor materials, and the bandgap resonance of semiconductor materials is very nonlinear optically, resulting in a large Δn'. This is very unfavorable for semiconductor materials working in the bandgap resonance. If the resonance region is avoided, it will lead to a decrease in nonlinearity;

When organic polymer materials and glass materials are used as carriers, the absorption peak can be avoided. The main disadvantage of organic polymer materials is that the light damage threshold is low, which needs to be further solved;

Glass materials, especially chalcogenide halide glass (referred to as sulfur halide glass) overcome the shortcomings of many of the above materials, and have high third-order nonlinear coefficients, short response time and low loss. In addition, glass properties are stable, It has wide transmission range, easy processing and low cost. It is an excellent material for preparing nonlinear optical waveguides. As a new nonlinear material, it has attracted more and more attention. The current glass optical waveguide is mainly prepared by ion-exchanging oxide glass-based glass with molten nitrate salt. The nonlinear coefficient of oxide glass is low, so it is mainly used in the preparation of linear optical devices.

To sum up, a nonlinear optical waveguide based on inorganic glass with high trivalent nonlinear coefficient should be researched and developed as soon as possible to meet the needs of the rapidly developing information technology.

Contents of the invention

The purpose of the present invention is to disclose a method for preparing a nonlinear optical waveguide with sulfur halide glass as a carrier by using a special molten salt through ion exchange.

Design of the present invention is such:

Studies have found that the nonlinear coefficient of chalcogenide glass is much larger than that of ordinary oxide glass and fluoride glass, and it is an excellent material for preparing nonlinear optical waveguides. However, since the transmission range of most chalcogenide glasses is only within 2-20 μm, The general communication window is around 0.98, 1.31 and 1.55 μm, so it is difficult for chalcogenide glass to be directly used as a nonlinear optical waveguide material. The loss of fluoride glass is the lowest, but its chemical stability is poor, and it is easy to be corroded by the environment and affect the working performance. The present invention adds halides to chalcogenide glass to form a new type of chalcogenide glass system—GeS ₂ -Ga ₂ S ₃ -Y (Y is one of KCl, KBr, KI, AgBr or AgI) , due to the addition of halides, the glass has the basic advantages of chalcogenide glasses and halide glasses, and suppresses the weaknesses of the two to a certain extent. Said glass not only has a wide light transmission range (0.42-11.5 μm) and good physical and chemical properties, but also contains monovalent metal ions, making it an excellent material for preparing nonlinear optical waveguides by ion exchange.

According to above-mentioned design, the present invention proposes following technical scheme:

The chemical structure of said nonlinear sulfur halide glass of the present invention is as follows:

GeS ₂ -Ga ₂ S ₃ -Y

in:

Y is one of KCl, KBr, KI, AgBr or AgI;

Its composition ratio is:

GeS ₂ -Ga ₂ S ₃ 70%～90%

Y 30%～10%

The above are mole percentages.

The light transmission range of the said glass is quite wide, including two regions of visible light and infrared (0.42-11.5μm), the transmittance is as high as 80% (thickness 3mm), the loss is low, and the nonlinear refractive index change Δn' is as high as 2.0- 2.5, the nonlinear effect is obvious, the nonlinear polarization coefficient χ is in the range of 10 ^-11 -10 ^-12 esu, the physical and chemical properties are good, and it is an excellent nonlinear optical waveguide material.

The melting of glass adopts the traditional quartz ampoule vacuum-sealed high-temperature (950-110° C.) melting method, which is a conventional method, which has been described in many patents and documents, and will not be repeated in the present invention. Cl, Br and I may be selected from KCl, KBr or KI, respectively; Ag may be selected from AgBr or AgI, respectively.

The above-mentioned thiohalide glasses can be used to prepare nonlinear optical waveguides.

The optical waveguide uses the above-mentioned sulfur halide glass as a carrier, its effective diffusion coefficient is 0.05×10 ^-10 cm ² S ^-1 to 700×10 ^-10 cm ² S ^-1 , and the refractive index difference Δn is 0.001-0.04 , The exchange depth is 1 μm ~ 1000 μm.

Said optical waveguide is also prepared like this:

Put the above-mentioned sulfur halide glass in an exchanger, and carry out ion exchange reaction with organic molten salt under the protection of inert gas. The organic molten salt has monovalent alkali metal cations, such as Na ⁺ , K ⁺ , Ag ⁺ , Cs ⁺ , Rb ⁺ organic salts such as one or more of citrate, stearate, oleate or palmitate, etc., the cations in the organic salts and the Ag in the glass or K for Na ⁺ -K ⁺ , Na ⁺ -Ag ⁺ , K ⁺ -Ag + , Cs ⁺ -K ⁺ , Rb ^{+ -K + ,} Rb ⁺ -Ag ⁺ , Cs ⁺ -Ag ⁺ ion exchange respectively to obtain The so-called nonlinear optical waveguide.

The exchange time is 1 hour to 80 hours, and the temperature is 210°C-310°C. If the temperature is too high, the structure inside the glass will relax, and the refractive index difference caused by ion exchange will disappear; The diffusion coefficient of the exchange is too small to make the ion exchange reaction difficult to proceed. Therefore, the preferred temperature is 230°C to 290°C.

The exchange depth can be controlled by adjusting the exchange time, and the exchange depth can reach 8-1200 μm, and the refractive index difference Δn is between 0.001-0.04. Secondary ion exchange can also be performed to prepare buried optical waveguides.

The biggest advantage of the optical waveguide of the present invention is low cost, simple process, obvious nonlinear phenomenon of the optical waveguide, easy coupling with optical fiber, wide light wave transmission range, and wide application range of the optical waveguide. Excellent carrier for integrating optics in the circuit.

Specific implementation method

The relevant content of the present invention will be further described below through examples, but the examples do not limit the protection scope of the present invention.

Example 1

Put 50GeS ₂ -25Ga ₂ S ₃ -25AgI glass with a diameter of 12mm and a thickness of 4mm and 100ml potassium oleate molten salt in the exchanger, and carry out K ⁺ -Ag ⁺ ion exchange under the protection of nitrogen at 270°C. The time is 30 hours, the obtained K ⁺ ion exchange depth is 256 μm, the effective diffusion coefficient is 60.7×10 ^-10 cm ² S ^-1 , and the refractive index difference Δn is 0.02.

Example 2

Put 60GeS ₂ -20Ga ₂ S ₃ -20AgI glass with a diameter of 12mm and a thickness of 4mm and 100ml potassium citrate molten salt in the exchanger, and carry out K ⁺ -Ag ⁺ ion exchange under the protection of nitrogen at 270°C. The time is 10 hours, the obtained K ⁺ ion exchange depth is 205 μm, and the refractive index difference Δn is 0.01.

Example 3

Put 50GeS ₂ -40Ga ₂ S ₃ -10KI glass with a diameter of 12mm and a thickness of 4mm and 100ml of cesium oleate molten salt into the exchanger, and conduct Cs ⁺ -Kg ⁺ ion exchange under the protection of nitrogen at 270°C. The time is 30 hours, and the obtained Cs ⁺ ion exchange depth is 9 μm, and the refractive index difference Δn is 0.03.

Example 4

Put the 50GeS ₂ -25Ga ₂ S ₃ -25KI glass with a diameter of 12mm and a thickness of 4mm and a mixed molten salt of potassium oleate and cesium oleate (1:1, weight ratio) in an exchanger, at 270°C under nitrogen In a protected environment, Cs ⁺ -Kg ⁺ ion exchange is carried out, the exchange time is 30 hours, the obtained Cs ⁺ ion exchange depth is 8 μm, and the refractive index difference Δn is 0.02.

Claims (2)

1. A method for preparing nonlinear sulfur-halide glass optical waveguide by ion exchange, which places sulfur-halide glass in an exchanger and carries out ion exchange reaction with organic molten salt to obtain nonlinear sulfur-halide glass optical waveguide, which is characterized in that: The organic molten salt is one or more of Na ⁺ , K ⁺ , Ag ⁺ , Cs ⁺ , Rb ⁺ citrate, stearate, oleate or palmitate; ion exchange reaction The time is 1-80 hours, the reaction temperature is 210°C-310°C; the ion exchange reaction is carried out under the protection of an inert gas. 2. The preparation method according to claim 1, wherein the temperature of said ion exchange reaction is 230°C-290°C.