A wavelength division multiplexer with high reflection isolation

Abstract

The invention provides a high reflection isolation wavelength division multiplexer, comprising a dual fiber collimator, a three-way light surface prism and a single fiber collimator arranged in sequence along the optical path propagation order, wherein the front lower end of the three-way light surface prism has a light-transmitting surface S1 with an angle of α1 with the vertical axis, and the light-transmitting surface S1 is plated with a λ1 anti-reflection film and a λ2 anti-reflection film; the front upper end of the three-way light surface prism has a light-transmitting surface S2 with an angle of α2 with the vertical axis, and the light-transmitting surface S2 is plated with a λ1 high reflection film and a λ2 anti-reflection film; the rear end of the three-way light surface prism has a light-transmitting surface S3 with an angle of α3 with the vertical axis, and the light-transmitting surface S3 is plated with a λ1 anti-reflection film and a λ2 high reflection film. The invention has high reflection isolation.

Description

Technical Field

[0001] The invention relates to the field of optical fiber communication, and in particular to a high-reflection isolation wavelength division multiplexer. Background Art

[0002] Wavelength division multiplexing is a technology that combines two or more optical carrier signals of different wavelengths through a multiplexer at the transmitting end and couples them to the same optical fiber of the optical line for transmission; at the receiving end, the optical carriers of various wavelengths are separated by a demultiplexer, and then further processed by the optical receiver to restore the original signal. This technology of simultaneously transmitting two or more optical signals of different wavelengths in the same optical fiber is called wavelength division multiplexing.

[0003] Isolation refers to the amount of light energy from the device port entering the non-specified output port. It is an important performance indicator for many optical communication devices. Although the single transmission isolation of thin film filter technology can be above 50dB, the single reflection isolation is difficult to reach 25dB. With the development of optical fiber communication technology, the wavelength isolation requirements for wavelength division multiplexing devices are getting higher and higher. For example, fiber-to-the-home technology requires more than 45dB. Existing optical wavelength division multiplexers / demultiplexers can hardly achieve a reflection isolation of more than 40dB by relying only on a film in front of the lens.

[0004] The Chinese utility model with the authorization announcement number CN2450830Y discloses a high isolation wavelength division multiplexer. In order to make the separated optical carriers have high isolation, an anti-reflection film is plated on one side of the optical fiber containing the emitting light or an optical sheet with an anti-reflection film is fixed on the light-emitting end face of the dual optical fiber head in the existing wavelength division multiplexer structure, and a WDM film is plated on the other optical fiber end face of the dual optical fiber head containing the receiving light or a WDM film is fixed. Figure 1 However, coating two different film systems or attaching two optical thin films on the tiny dual-fiber head end face is a complex process with high cost and difficult to ensure reliability.

[0005] The Chinese utility model with the authorization announcement number CN2850146Y discloses a high-isolation optical wavelength division multiplexer / demultiplexer device, including a three-fiber head with different film coatings, a lens, a filter, and a reflector; one of the fiber ends of the three-fiber head with different film coatings is coated with a filter film, and the other two fiber ends are coated with anti-reflection films; when the light is reflected back to the optical fiber with the end face coated with the filter film through the first filter, the filter film coated on the optical fiber end face isolates the optical signal again, thereby improving the reflection isolation; and the light transmitted through the first filter is coupled back to the third optical fiber through the reflector. The three-fiber head with different film coatings can be integrated or assembled. The utility model adopts a three-fiber head, which can be assembled into one by three single fiber heads with different film systems or optical thin films with different film systems on the end faces, or assembled into one by a double fiber head and a single fiber head with different film systems or optical thin films with different film systems on the end faces, see Figure 2 The utility model solves the complex process of coating different film systems on the same optical fiber head, but introduces new devices into the wavelength division multiplexer, which increases the difficulty of assembly and the cost of the device. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a high reflection isolation wavelength division multiplexer with high reflection isolation.

[0007] The present invention is achieved in that:

[0008] A high-reflection isolation wavelength division multiplexer comprises a dual-fiber collimator, a three-way light-surface prism and a single-fiber collimator which are sequentially arranged along an optical path propagation order, wherein the front lower end of the three-way light-surface prism has a light-transmitting surface S1 with an angle of α1 with a vertical axis, and the light-transmitting surface S1 is plated with a λ1 anti-reflection film and a λ2 anti-reflection film; the front upper end of the three-way light-surface prism has a light-transmitting surface S2 with an angle of α2 with the vertical axis, and the light-transmitting surface S2 is plated with a λ1 high-reflection film and a λ2 high-reflection film; the rear end of the three-way light-surface prism has a light-transmitting surface S3 with an angle of α3 with the vertical axis, and the light-transmitting surface S3 is plated with a λ1 anti-reflection film and a λ2 high-reflection film.

[0009] Furthermore, the angles α1, α2 and α3 between the light-transmitting surface S1, the light-transmitting surface S2 and the light-transmitting surface S3 of the three-light-transmitting surface prism and the vertical axis satisfy the following relationship:

[0010]

[0011]

[0012] Wherein, t represents the center thickness of the three-way light-surface prism, γ10 represents the angle between the light beam sent by the dual-fiber collimator to the light-transmitting surface S1 and the optical axis; γ20 represents the angle between the light beam returned by the light-transmitting surface S2 to the dual-fiber collimator and the optical axis; n represents the refractive index of the three-way light-surface prism; d1 represents the distance from the vertex of the lens output surface of the dual-fiber collimator to the intersection of the light-transmitting surface S1 and the light-transmitting surface S2 of the three-way light-surface prism.

[0013] Furthermore, when the beam crossing angle β of the dual-fiber collimator is 3.7°, α1=8°, α2=-10°, α3=-0.34°, d1=5mm, and the center thickness t of the three-way optical surface prism is 5.16mm.

[0014] Furthermore, when the beam crossing angle β of the dual-fiber collimator is 3.7°, α1=6°, α2=-6°, α3=0°, d1=5mm, and the center thickness t of the three-way optical surface prism is 11.93mm.

[0015] Furthermore, the dual-fiber collimator includes a first lens, a first capillary, an input optical fiber and an output optical fiber. The first capillary and the first lens are arranged in sequence along the optical path. An input optical fiber fixing hole and an output optical fiber fixing hole are symmetrically distributed along the optical axis at the axial center of the first capillary. The input optical fiber and the output optical fiber are respectively glued into the input optical fiber fixing hole and the output optical fiber fixing hole.

[0016] Furthermore, the dual-fiber collimator also includes a first outer sleeve, and the first capillary and the first lens are installed in the first outer sleeve.

[0017] Furthermore, the first capillary is a glass capillary, and the first outer sleeve is a glass sleeve.

[0018] Furthermore, the single fiber collimator includes a second lens, a second capillary and a receiving optical fiber. The second lens and the second capillary are arranged in sequence along the optical path. A receiving optical fiber fixing hole is provided at the axial center of the second capillary, and the receiving optical fiber is bonded in the receiving optical fiber fixing hole.

[0019] Furthermore, the single optical fiber collimator also includes a second outer sleeve, and the second capillary and the second lens are installed in the second outer sleeve.

[0020] Furthermore, the second capillary is a glass capillary, and the second outer sleeve is a glass sleeve.

[0021] The advantages of the present invention are:

[0022] 1. The present invention uses a three-way light-surface prism to split two beams of light (λ1 light and λ2 light) of different wavelengths, and achieves high isolation of λ1 light by realizing corresponding transmission and reflection on the light-passing surfaces S1, S2 and S3 of the three-way light-surface prism. Through two reflections on the light-passing surfaces S2 and S3, the reflection isolation reaches more than 40 dB, which overcomes the disadvantage of low reflection isolation of a conventional single diaphragm.

[0023] 2. The present invention coats different film systems on different light-passing surfaces of the three-pass light-passing surface prism, which greatly reduces the difficulty of the coating process and overcomes the process difficulty of placing a film on the end surface of a double optical fiber head;

[0024] 3. The dual-fiber collimator used in the present invention is an integral dual-fiber head structure, which does not require the assembly of fiber heads with different film systems, making the overall device structure more compact and reducing the difficulty of assembly process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with embodiments with reference to the accompanying drawings.

[0026] Figure 1 It is a schematic diagram of a specific structure in the prior art.

[0027] Figure 2 It is a schematic diagram of a specific structure in another prior art.

[0028] Figure 3 The present invention is a schematic structural diagram of a high reflection isolation wavelength division multiplexer.

[0029] Figure 4 Schematic diagram of the optical path transmission of a light beam through a three-way optical surface prism in the present invention.

[0030] Description of the numbers in the figure:

[0031] 1-dual fiber collimator, 11-first lens, 12-first capillary, 121-input fiber fixing hole, 122-output fiber fixing hole, 13-input fiber, 14-output fiber, 15-first outer sleeve, 2-three-way optical surface prism, 3-single fiber collimator, 31-second lens, 32-second capillary, 321-receiving fiber fixing hole, 33-receiving fiber, 34-second outer sleeve, 100-light beam sent by the dual fiber collimator to the light-transmitting surface S1, 101-light beam returned to the dual fiber collimator by the light-transmitting surface S2, O-optical axis. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with specific embodiments, but the structure of the present invention is not limited to the following embodiments.

[0033] See also Figure 3 and Figure 4 As shown, a high reflection isolation wavelength division multiplexer of the present invention comprises a dual-fiber collimator 1, a three-way light-surface prism 2 and a single-fiber collimator 3 which are sequentially arranged along the optical path propagation order, wherein the front lower end of the three-way light-surface prism 2 has a light-transmitting surface S1 with an angle of α1 with the vertical axis, and the light-transmitting surface S1 is coated with a λ1 anti-reflection film and a λ2 anti-reflection film, which can enhance the transmittance of light with wavelengths λ1 and λ2; the front upper end of the three-way light-surface prism 2 has a light-transmitting surface S2 with an angle of α2 with the vertical axis, and the light-transmitting surface S2 is coated with a λ1 high-reflection film and a λ2 anti-reflection film, which can enhance the transmittance of light with wavelengths λ1 and λ2. The three-way light-surface prism 2 has a light-transmitting surface S3 at an angle of α3 to the vertical axis at the rear end thereof, and the light-transmitting surface S3 is coated with a λ1 anti-reflection film and a λ2 high-reflection film, which can enhance the transmittance of the light of wavelength λ1 and reflect the light of wavelength λ2. The three-way light-surface prism 2 is adopted, and the three light-transmitting surfaces reflect and transmit the λ1 light and the λ2 light accordingly, so as to achieve the purpose of high isolation of the λ1 light. Different film systems are coated on different light-transmitting surfaces of the three-way light-surface prism 2, so that the difficulty of the coating process is greatly reduced, and the process difficulty of placing a film on the end face of a dual optical fiber head is overcome.

[0034] The angles α1, α2 and α3 corresponding to the light-passing surface S1, the light-passing surface S2 and the light-passing surface S3 of the three-light-passing surface prism 2 and the vertical axis satisfy the following relationship:

[0035]

[0036]

[0037] Wherein, t represents the center thickness of the three-way light-surface prism 2, γ10 represents the angle between the light beam 100 sent by the dual-fiber collimator 1 to the light-transmitting surface S1 and the optical axis O; γ20 represents the angle between the light beam 101 returned by the light-transmitting surface S2 to the dual-fiber collimator 1 and the optical axis O; n represents the refractive index of the three-way light-surface prism 2; d1 represents the distance from the vertex of the lens output surface of the dual-fiber collimator 1 to the intersection of the light-transmitting surface S1 and the light-transmitting surface S2 of the three-way light-surface prism 2.

[0038] Preferably, when the beam crossing angle β of the dual-fiber collimator 1 is 3.7°, α1=8°, α2=-10°, α3=-0.34°, d1=5mm, and the center thickness of the three-way light-surface prism 2 is t=5.16mm; when the beam crossing angle β of the dual-fiber collimator 1 is 3.7°, α1=6°, α2=-6°, α3=0°, d1=5mm, and the center thickness of the three-way light-surface prism 2 is t=11.93mm; the positive and negative of α1, α2 and α3 here refer to the different directions of beam deflection, the negative sign indicates clockwise rotation, and the positive sign indicates counterclockwise rotation.

[0039] Preferably, the structure of the dual-fiber collimator 1 is as follows:

[0040] The dual-fiber collimator 1 includes a first lens 11, a first capillary 12, an input optical fiber 13, an output optical fiber 14 and a first outer sleeve 15, wherein the first capillary 12 is a glass capillary, and the first outer sleeve 15 is a glass sleeve; the first capillary 12 and the first lens 11 are arranged in sequence along the optical path propagation sequence, and the first capillary 12 and the first lens 11 are installed in the first outer sleeve 15, and an input optical fiber fixing hole 121 and an output optical fiber fixing hole 122 are symmetrically distributed along the optical axis O at the axial center of the first capillary 12, and the input optical fiber 13 and the output optical fiber 14 are respectively bonded to the input optical fiber fixing hole 121 and the output optical fiber fixing hole 122.

[0041] Preferably, the structure of the single fiber collimator 3 is as follows:

[0042] The single fiber collimator 3 includes a second lens 31, a second capillary 32, a receiving optical fiber 33 and a second outer sleeve 34, wherein the second capillary 32 is a glass capillary and the second outer sleeve 34 is a glass sleeve; the second lens 31 and the second capillary 32 are arranged in sequence along the optical path propagation sequence, and the second capillary 32 and the second lens 31 are installed in the second outer sleeve 34; a receiving optical fiber fixing hole 321 is provided at the axial center of the second capillary 32, and the receiving optical fiber 33 is glued in the receiving optical fiber fixing hole 321.

[0043] Working principle description:

[0044] The λ1 light and λ2 light of different wavelengths are emitted from the input optical fiber 13 of the dual-fiber collimator 1, and are incident on the light-transmitting surface S1 of the three-way optical surface prism 2 after being collimated by the first lens 11. The light-transmitting surface S1 is coated with anti-reflection films for λ1 and λ2. The λ1 light and λ2 light continue to propagate to the light-transmitting surface S3 of the three-way optical surface prism 2; the light-transmitting surface S3 is coated with a film system for anti-reflection of λ1 and high reflection of λ2. The λ1 light is emitted from the three-way optical surface prism 2 to the single-fiber collimator 3, and is coupled into the receiving optical fiber 33 through the second lens 31; the λ2 light and the residual λ1 light that is not completely anti-reflected are reflected on the light-transmitting surface S2 of the three-way optical surface prism 2; the light-transmitting surface S2 is coated with a film system for high reflection of λ1 and anti-reflection of λ2, and a small amount of residual λ1 light is reflected from the light-transmitting surface S2, and the reflected light deviates from the receiving range of the output optical fiber 14 of the dual-fiber collimator 1, thereby achieving the purpose of high isolation of the λ1 light. The λ2 light is emitted from the three-way optical surface prism 2 to the dual fiber collimator 1, and then coupled by the first lens 11 into the output fiber 14. Through different angle combinations, the λ1 light and the λ2 light are coupled to the receiving fiber 33 and the output fiber 14 respectively.

[0045] The advantages of the present invention are as follows:

[0046] 1. The present invention uses a three-way light-surface prism 2 to split two beams of light (λ1 light and λ2 light) of different wavelengths, and achieves high isolation of λ1 light by realizing corresponding transmission and reflection on the light-passing surfaces S1, S2 and S3 of the three-way light-surface prism 2. Through the two reflections of the light-passing surfaces S2 and S3, the reflection isolation reaches more than 40 dB, which overcomes the disadvantage of low reflection isolation of a conventional single diaphragm.

[0047] 2. The present invention coats different film systems on different light-passing surfaces of the three-pass light-surface prism 2, which greatly reduces the difficulty of the coating process and overcomes the process difficulty of placing a film on the end surface of a double optical fiber head;

[0048] 3. The dual-fiber collimator 1 used in the present invention is an integral dual-fiber head structure, which does not require the assembly of fiber heads with different film systems, making the overall device structure more compact and reducing the difficulty of assembly process.

[0049] Although the specific implementation modes of the present invention are described above, those skilled in the art should understand that the specific implementation modes described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A high reflection isolation wavelength division multiplexer, characterized in that: It comprises a dual-fiber collimator, a three-way light-surface prism and a single-fiber collimator which are sequentially arranged along the optical path propagation order, wherein the front lower end of the three-way light-surface prism has a light-transmitting surface S1 with an angle of α1 with the vertical axis, and the light-transmitting surface S1 is plated with a λ1 anti-reflection film and a λ2 anti-reflection film; the front upper end of the three-way light-surface prism has a light-transmitting surface S2 with an angle of α2 with the vertical axis, and the light-transmitting surface S2 is plated with a λ1 high-reflection film and a λ2 anti-reflection film; the rear end of the three-way light-surface prism has a light-transmitting surface S3 with an angle of α3 with the vertical axis, and the light-transmitting surface S3 is plated with a λ1 anti-reflection film and a λ2 high-reflection film; The angles α1, α2 and α3 corresponding to the light-passing surface S1, the light-passing surface S2 and the light-passing surface S3 of the three-light-passing surface prism and the vertical axis satisfy the following relationship: Wherein, t represents the center thickness of the three-way light-surface prism, γ10 represents the angle between the light beam sent by the dual-fiber collimator to the light-passing surface S1 and the optical axis; γ20 represents the angle between the light beam returned to the dual-fiber collimator by the light-passing surface S2 and the optical axis; n represents the refractive index of the three-way light-surface prism; d1 represents the distance from the vertex of the lens exit surface of the dual-fiber collimator to the intersection of the light-passing surface S1 and the light-passing surface S2 of the three-way light-surface prism; The dual-fiber collimator includes a first lens, a first capillary, an input optical fiber and an output optical fiber. The first capillary and the first lens are arranged in sequence along the optical path. An input optical fiber fixing hole and an output optical fiber fixing hole are symmetrically distributed along the optical axis at the axial center of the first capillary. The input optical fiber and the output optical fiber are respectively glued into the input optical fiber fixing hole and the output optical fiber fixing hole.

2. A high reflection isolation wavelength division multiplexer as claimed in claim 1, characterized in that: When the beam crossing angle β of the dual-fiber collimator is 3.7°, α1=8°, α2=-10°, α3=-0.34°, d1=5mm, and the center thickness t of the three-way optical surface prism is 5.16mm.

3. A high reflection isolation wavelength division multiplexer as claimed in claim 1, characterized in that: When the beam crossing angle β of the dual-fiber collimator is 3.7°, α1=6°, α2=-6°, α3=0°, d1=5mm, and the center thickness t of the three-way optical surface prism is 11.93mm.

4. A high reflection isolation wavelength division multiplexer as claimed in claim 1, characterized in that: The dual-fiber collimator further comprises a first outer sleeve, in which the first capillary and the first lens are installed.

5. A high reflection isolation wavelength division multiplexer as claimed in claim 4, characterized in that: The first capillary is a glass capillary, and the first outer sleeve is a glass sleeve.

6. A high reflection isolation wavelength division multiplexer as claimed in claim 1, characterized in that: The single fiber collimator comprises a second lens, a second capillary and a receiving optical fiber. The second lens and the second capillary are arranged in sequence along the optical path. A receiving optical fiber fixing hole is provided at the axial center of the second capillary. The receiving optical fiber is bonded in the receiving optical fiber fixing hole.

7. A high reflection isolation wavelength division multiplexer as claimed in claim 6, characterized in that: The single optical fiber collimator further comprises a second outer sleeve, in which the second capillary and the second lens are installed.

8. A high reflection isolation wavelength division multiplexer as claimed in claim 7, characterized in that: The second capillary is a glass capillary, and the second outer sleeve is a glass sleeve.

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