CN102841396A - Light filtering device - Google Patents

Abstract

The invention relates to a light filtering device, which comprises a glass substrate and a light filtering film, wherein the light filtering film is arranged on the glass substrate and is provided with a Fabry-Perot resonant cavity (Fabry-Perot resonator) structure formed by alternately stacking a high-refraction film layer and a low-refraction film layer, and the basic optical thicknesses of the high-refraction film layer and the low-refraction film layer are the quarter central wavelength (lambda) of incident light₀/4) (ii) a The Fabry-Perot resonant cavity structures are sequentially stacked on the glass substrate, and each Fabry-Perot resonant cavity structure comprises two high-reflector film layers, a spacing layer positioned between the two high-reflector film layers, a spacing layer of the Fabry-Perot resonant cavity structure closest to the glass substrate and a spacing layer of the Fabry-Perot resonant cavity structure farthest from the glass substrate, wherein the optical thickness of the spacing layer is not less than 4 times of the basic optical thickness and not more than 14 times of the basic optical thickness.

Description

filter device

technical field

The present invention relates to a filter device, and more specifically refers to a filter device that can be used in Coarse Wavelength Division Multiplexing (CWDM).

Background technique

With the popularization of computers and the rapid development of network technology, the use of the network can quickly obtain data or provide services. Optoelectronic communication can provide fast and large amount of information transmission, therefore, the optoelectronic industry is valued by people from all walks of life and related industries. The photoelectric industry, which is currently developing rapidly, is an application field produced by combining electronics and optics. Among them, optical networking technology is valued and widely used.

Optical fiber network technology is a communication technology that uses optical fiber as a data transmission medium, allowing multiple different processing systems (such as computer systems or telephone systems) to transmit analog or digital data through laser beams. type of signal. In addition, since the laser beam has a higher frequency than electric waves, and the loss of the laser beam in the optical fiber is extremely small, its transmission speed and efficiency are much higher than traditional wired and wireless communication systems.

In optical fiber network technology, Coarse Wavelength Division Multiplexing (CWDM) is most commonly used. The above-mentioned sparse wavelength division multiplexing integrates multiple Channels of different wavelengths are in the same optical fiber, and a demultiplexer is used at the receiving end to separate all wavelengths into different optical fibers. The filter film of the filter device used in the above-mentioned sparse wavelength division multiplexing has a Fabry-Perot resonator structure in which multiple cavities are alternately stacked by high-refraction film layers and low-refraction film layers. And one of the structural designs of the filter film from the air end (Air) to the glass substrate end (NS) is as follows:

Air/H(LH)^2 2L(HL)^3 H(LH)^3 4L(HL)^3 H(LH)^4 6L(HL)^4 H(LH)^36L(HL)^3 H (LH)^4 6L(HL)^4 H(LH)^3 6L(HL)^3 H(LH)^4 6L(HL)^4 H(LH)^34L(HL)^3 H(LH) ^3 2L(HL)^2 H/NS

Wherein, H represents the high refraction film layer that optical thickness is λ ₀ /4; L represents the low refraction film layer that optical thickness is λ ₀ /4; λ ₀ is the central wavelength of incident light;

In this way, multiple channels with different wavelengths can be integrated into the same optical fiber by utilizing the structural design of the above-mentioned optical filter device and matching with the wavelength multiplexer.

However, please refer to Figure 1. Although the structural design of the above-mentioned filter device can achieve the purpose of integrating channels, it cannot effectively reduce the stopband of each channel, and each channel has its fixed bandwidth. , when the suppression frequency band of each channel is too large, it will interfere with adjacent channels, which will affect the communication quality of optical fiber network technology.

Contents of the invention

The technical problem to be solved by the present invention is to provide a filter device whose structural design of the filter film can effectively Reduce the stop band (stopband) of each channel to a large extent.

The technical solution adopted by the present invention to solve the technical problem is to provide a filter device, which includes a glass substrate and a filter film, wherein the filter film is arranged on the glass substrate and has a plurality of cavities made of a high refraction film. A Fabry-Perot resonator (Fabry-Perotresonator) structure formed by stacking layers and low-refractive film layers alternately, and the basic optical thickness of the above-mentioned high-refractive film layer and low-refractive film layer is a quarter center of the incident light wavelength (λ ₀ /4); these Fabry-Perot resonator structures are stacked on the glass substrate in sequence, and each of the Fabry-Perot resonator structures includes two layers of high reflection mirror film layers and a A spacer layer positioned between the two high reflection mirror film layers;

In order to achieve the above-mentioned purpose, the optical thickness of the spacer layer of the Fabry-Perot cavity structure closest to the glass substrate and the spacer layer of the Fabry-Perot cavity structure farthest away from the glass substrate in the filter film Not less than 4 times the basic optical thickness, and not more than 14 times the basic optical thickness.

In order to achieve a better effect, the optical thickness of the spacer layer of the Fabry-Perot cavity structure closest to the glass substrate in the filter film is 4 times the basic optical thickness, 6 times the basic optical thickness, and 8 times the basic optical thickness , 10 times the basic optical thickness, 12 times the basic optical thickness and 14 times the basic optical thickness.

In order to achieve a better effect, the optical thickness of the spacer layer of the Fabry-Perot cavity structure farthest from the glass substrate in the filter film is 4 times the basic optical thickness, 6 times the basic optical thickness, and 8 times the basic optical thickness , 10 times the basic optical thickness, 12 times the basic optical thickness and 14 times the basic optical thickness.

Thereby, using the above structural design, the stop frequency band of each channel can be effectively reduced.

Description of drawings

FIG. 1 is a waveform diagram of each channel of an existing optical filter device.

Fig. 2 is a schematic structural view of the filter device of the present invention.

Fig. 3 is a waveform diagram of each channel of the optical filter device of the present invention.

Detailed ways

In order to illustrate the present invention more clearly, preferred embodiments are given together with diagrams in detail as follows.

Please refer to FIG. 2 , the optical filter device 1 of the present invention is suitable for Coarse Wavelength Division Multiplexing (CWDM). The filter device 1 includes a glass substrate 10 and a filter film 20. In the present embodiment, the center wavelength λ ₀ of the incident light is 1530 nanometers (nm) as an example for illustration, wherein:

The glass substrate 10 is composed of elements such as silicon oxide, barium, lithium, and sodium.

The filter film 20 is disposed on the glass substrate 10, and has a nine-cavity Fabry-Perot resonator structure 22 formed by alternately stacking high-refractive film layers and low-refractive film layers, and each of the The Fabry-Perot resonator structure 22 is composed of two layers of high reflection mirror film layers 221 and a spacer layer 222 between the two layers of high reflection mirror film layers 221 . In addition, the basic optical thickness of the above-mentioned high-refractive film layer and low-refractive film layer is λ ₀ /4 (that is, 382.5 nanometers), and the low-refractive film layer is made of silicon oxide, and the refractive index is 1.38-1.44. The high refraction film layer is made of tantalum oxide material, and the refraction index is 2.1-2.7.

Thus, the nine-cavity Fabry-Perot resonator structure 22 of the filter film 20 in this embodiment is as follows in sequence:

H(LH)^2 4L(HL)^3; H(LH)^3 4L(HL)^3; H(LH)^4 6L(HL)^4; H(LH)^3 6L(HL)^ 3; H(LH)^4 6L(HL)^4; H(LH)^3 6L(HL)^3; H(LH)^4 6L(HL)^4; H(LH)^34L(HL) ^3; H(LH)^3 4L(HL)^2 H/NS

Among them, H represents a high-refraction film layer with an optical thickness of λ ₀ /4; L represents a low-refraction film layer with an optical thickness of λ ₀ /4; NS is a glass substrate;

The difference of the present invention is that the first cavity Fabry-Perot cavity structure 22 closest to the glass substrate in the filter film 20 of the optical filter device 1, and the ninth cavity structure farthest from the glass substrate Structural design of the Brie-Perot cavity structure 22.

It can be known from the above design formula that the first cavity Fabry-Perot cavity structure 22 is H(LH)^34L(HL)^2H, wherein H(LH)^3 and (HL)^2H are The high reflection mirror film layer 221 of the first cavity Fabry-Perot resonator structure 22, and the 4L between H(LH)^3 and (HL)^2H is the first cavity Fabry-Perot The spacer layer 222 of the resonant cavity structure 22. And this ninth cavity Fabry-Perot cavity structure 22 is H(LH)^2 4L(HL)^3, wherein, H(LH)^2 and (HL)^3 are the ninth cavity fabric The high reflection mirror film layer 221 of Li-Perot resonator structure 22, and the 4L between H(LH)^2 and (HL)^3 is the interval of the ninth cavity Fabry-Perot resonator structure 22 Layer 222.

In this way, referring to FIG. 3, the present invention increases the spacer layer 222 of the first cavity Fabry-Perot resonator structure 22 and the ninth cavity Fabry-Perot cavity structure 22 to four times basically The design of the optical thickness can effectively reduce the stopband of each channel, so that each channel will not interfere with other adjacent channels, thereby improving the communication quality of the optical fiber network technology.

It is worth mentioning that, under the condition of not distorting the waveform of each channel, the spacer layer of the Fabry-Perot cavity structure closest to the glass substrate and the Fabry-Perot cavity structure farthest from the glass substrate The optical thickness of the spacer layer of the structure can also be changed to 4 to 14 times the basic optical thickness according to the environment or requirements. Optical thickness, 10 times the basic optical thickness, 12 times the basic optical thickness or 14 times the basic optical thickness.

It must be noted that the structural design of the filter device of the present invention is not limited to the number of structural layers or the structural design disclosed in the above design formula, as long as the Fabry-Perot cavity structure closest to the glass substrate is added The optical thickness of the spacer layer and the spacer layer of the Fabry-Perot resonator structure farthest from the glass substrate to achieve the purpose of reducing the stop frequency band of each channel should belong to other feasible implementation aspects of the present invention. , and any equivalent structure and manufacturing method changes made by applying the specification and claims of the present invention should be included in the patent scope of the present invention.

Claims (10)

1. A filter device, characterized in that it comprises: glass substrates; and The filter film is set on the glass substrate and has a Fabry-Perot resonant cavity structure in which multiple cavities are alternately stacked with high-refraction film layers and low-refraction film layers, and the above-mentioned high-refraction film layers and low-refraction film layers are The basic optical thickness is λ ₀ /4, where λ ₀ is the central wavelength of the incident light; these Fabry-Perot resonator structures are stacked on the glass substrate in sequence, and each Fabry-Perot resonator The structure includes two layers of high reflective mirror film layers and a spacer layer between the two high reflective mirror film layers; Wherein, the optical thickness of the spacer layer of the Fabry-Perot cavity structure closest to the glass substrate in the filter film and the spacer layer of the Fabry-Perot cavity structure farthest from the glass substrate are not less than 4 times The basic optical thickness is not greater than 14 times the basic optical thickness. 2. The optical filter device according to claim 1, wherein the optical thickness of the spacer layer of the Fabry-Perot resonator structure closest to the glass substrate in the optical filter film is 4 times of the basic optical thickness, 6 times the basic optical thickness, 8 times the basic optical thickness, 10 times the basic optical thickness, 12 times the basic optical thickness and 14 times the basic optical thickness. 3. The optical filter device according to claim 1, wherein the optical thickness of the spacer layer of the Fabry-Perot resonator structure farthest from the glass substrate in the optical filter film is 4 times of the basic optical thickness, 6 times the basic optical thickness, 8 times the basic optical thickness, 10 times the basic optical thickness, 12 times the basic optical thickness and 14 times the basic optical thickness. 4. The filter device according to claim 1, wherein the center wavelength of the incident light is 1530 nm. 5. The filter device according to claim 1, characterized in that, the refractive index of the low-refractive film layer is 1.38-1.44. 6. The filter device according to claim 5, wherein the low refraction film layer is made of silicon oxide. 7. The filter device according to claim 1, characterized in that, the refractive index of the high refraction film layer is 2.1-2.7. 8. The optical filter device according to claim 7, wherein the high refraction film layer is made of tantalum oxide. 9. The filter device according to claim 1, wherein the filter film is formed by sequentially stacking nine-cavity Fabry-Perot resonator structures, and the structure of the filter film satisfies the following design formula: H(LH)^2 AL(HL)^3 H(LH)^3 4L(HL)^3 H(LH)^4 6L(HL)^4 H(LH)^3 6L(HL)^3 H( LH)^4 6L(HL)^4 H(LH)^3 6L(HL)^3 H(LH)^4 6L(HL)^4 H(LH)^3 4L(HL)^3 H(LH) ^3 BL(HL)^2 H/NS, wherein H represents a high-refraction film layer with an optical thickness of λ ₀ /4; L represents a low-refraction film layer with an optical thickness of λ ₀ /4; NS is a glass substrate; 4 ≦A≦14; 4≦B≦14. 10. The filter device according to claim 9, wherein A in the design formula is one of 4, 6, 8, 10, 12 and 14; B in the design formula is 4, 6 , 8, 10, 12 and 14 one of them.

Images