CN1068895A - A kind of optical isolator - Google Patents

Abstract

This optical isolator is a passive device consisting of a pair of parallel Quadrilateral polarizing beam splitter, Faraday rotation element and after the analyzer Setting up an end-mirror configuration can triple the isolation ratio increase.

Description

The invention belongs to optical passive devices.

my country's "Laser and Infrared" published the "Polarization-Independent Optical Isolator" (Huazhong University of Science and Technology, Zhou Mi, Liu Deming, Huang Dexiu) published in the second issue of 1991. Although the optical isolator disclosed in the international community has broken The common practice of using calcite crystals and analyzers in the device is replaced by a polarizing beam splitter prism, thereby avoiding the disadvantages of using expensive calcite crystals to make catalysts and analyzers. However, this structure cannot achieve a double or triple increase. The isolation ratio of common isolators.

It is an object of the present invention to provide an optical isolator that doubles the isolation ratio.

In order to achieve the above object, the present invention takes the following technical measures: a pair of parallelogram polarized beamsplitter prisms are used to replace the polarizer and the analyzer, a Faraday light-applying element is arranged in the middle of them, and an end reflector is arranged at the rear 2 ports of the analyzer. , the light splitting and combining effect of the analyzer and the reflection effect of the end mirror, to double or triple the isolation ratio of the common isolator. As shown in Figure 1, I and II are polarization beam-splitting prisms, and the Faraday rotation element III is between them. Due to the polarization and beam-splitting characteristics of I and II, the incident light of any polarization state is reversely incident through port 1 and will be transformed after passing through I prism. Divided into two beams of light whose polarization directions are perpendicular to each other. After the two beams of light pass through the Faraday rotation optical element respectively, they are combined at the second polarization beam splitter II and then deflected out of the optical path to form an isolation effect. The leaked light from 2 ends shoot out. When it is reflected by the end reflector A and re-incided by the II prism, the same principle, the two beams of light decomposed by the leaked light will be combined at the I prism and then deflected out of the optical path 3 port again, which doubles the normal isolation. device isolation ratio. To triple the isolation ratio, the device is shown in Figure 2. An end reflector B is added to the front 3 ports of the polarizing beam splitter prism I, and the leaked light after the secondary isolation is reflected and combined at the prism II and then polarized. Optical path (4 ports)

Figure 1 is a schematic diagram of a double multiplier optical isolator.

Figure 2 is a schematic diagram of a triple multiplier optical isolator.

Advantage of the present invention is a lot, mainly shows in:

1. The effect of doubling or tripling the isolation ratio of ordinary isolators can be achieved by using end reflectors without adding an isolation system. Since the forward insertion loss of the isolated system is very low, but the reverse isolation ratio is high, this multiplier effect greatly improves the performance of the isolator.

2. Only by adjusting the end face reflector to tilt a small angle, it can avoid the situation that the leakage light generated during the back and forth reflection of the light through the reflector is recoupled to each port of the isolator, resulting in a decrease in the isolation ratio.

3. By adjusting the setting positions of the polarization beam splitters I and II and the forward optical rotation angle of the Faraday rotator, the order of the output ports of the isolator and the position of the reflectors can be adjusted conveniently, which brings great convenience to the processing.

4. Due to the use of a parallelogram polarization beam splitter prism, the isolator is applicable to incident light of any polarization state.

5. Parallelogram polarized beamsplitter prism is used as the starting and analyzing elements, so that the isolator forms multiple input and output ports, so this basic structure can be used to form a series of isolator products.

6. The parallelogram polarized beam splitter prism can be made of calcite crystal or ordinary glass. When made of ordinary glass, the polarized beam splitter film is formed by coating multi-layer dielectric film on its glued surface. This method is suitable for large-scale production and the cost is low. .

7. By adjusting the positions of the reflection and transmission bands of the multi-layer dielectric polarizing beam splitting film, the isolator can be applied to different light-passing bands.

8. By adjusting the optimal incident angle of the polarization beam splitter film, the reflection film can be directly coated on the corresponding position of the polarization beam splitter instead of the reflector to simplify the structure.

9. Parallelogram polarized beam splitter prism can also be made into right angle polarized beam splitter prism, which is convenient for directly coating reflective film.

10. The input and output ports of the isolator can be coupled with self-focusing rods with pigtails, so as to realize the optical fiber input of the optical isolator.

Claims (1)

1, a kind of optical isolator, it is made of pair of parallel quadrilateral polarization splitting prism and faraday optical rotation components, it is characterized by an end mirror (A) is set behind polarization splitting prism (II).

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