CN202677010U

CN202677010U - Free space isolator

Info

Publication number: CN202677010U
Application number: CN 201220281473
Authority: CN
Inventors: 白文; 邓云锋; 李连城
Original assignee: O Net Communications Shenzhen Ltd
Current assignee: O Net Technologies Shenzhen Group Co Ltd
Priority date: 2012-06-14
Filing date: 2012-06-14
Publication date: 2013-01-16
Anticipated expiration: 2022-06-14

Abstract

The utility model discloses a free space isolator. The free space isolator comprises a piece of polarizing film and a piece of one-quarter wave plate which are distributed along the direction of an optical axis, wherein when light is transmitted reversely, the light becomes linearly polarized light after passing the one-quarter wave plate and then is mostly absorbed by the polarizing film. The free space isolator is applied to a light path with low requirements for isolation, is simple in structure, easy in manufacturing of raw materials, and low in cost.

Description

A kind of free space isolator

Technical field

The utility model relates to the optical device in the fiber optic communication field, particularly a kind of free space isolator of simplifying cheaply encapsulation.

Background technology

Optoisolator is widely used in optical communication and industrial lasers application, wherein the main relevant free space isolator (Free Space Isolator) of polarization that uses in the laser instrument assembling.

As shown in Figure 1, a large amount of commercial free space isolators comprise the first polaroid 110, the second polaroid 130 and a slice 45 degree Faraday rotation sheets 120 compositions at present, 45 degree Faraday rotation sheets 120 are placed between the first polaroid 110 and the second polaroid 130, and the polarization direction of the first polaroid 110 and the second polaroid 130 differs 45 degree.When light positive to when transmission, the incident light part parallel with the first polaroid 110 polarization directions passed through the first polaroid 110, the part vertical with the polarization direction absorbed by the first polaroid 110, light by the first polaroid 110 enters Faraday rotation sheet 120 rear 45 degree that rotate under the Faraday effect effect, just in time parallel with the polarization direction of the second polaroid 130, therefore can loss-freely pass through the second polaroid 130.Please also refer to Fig. 2, when the light reverse transfer, wherein the part vertical with the second polaroid 130 polarization directions directly absorbed by the second polaroid 130, and then part lossless see through parallel with the second polaroid 130 polarization directions enter Faraday rotation sheet 120; Because the sense of rotation of Faraday rotation sheet 120 only depends on the transmission direction of magnetic direction and light, therefore when the light reverse transfer, sense of rotation when the light sense of rotation is transmitted with forward is consistent, arrive the first polaroid 110, this moment, the polarisation of light attitude was vertical with the polarization direction of the first polaroid 110, light is absorbed by the first polaroid 110, therefore can not project in the input light path.The free space isolator that is comprised of above-mentioned three parts is placed on the isolation that can realize in the light path more than the 30dB.

But, in the not high light path of some insulated degree requirements, when for example isolator is applied in the ONT Optical Network Terminal system, there is the problem of the superfluous wasting of resources of function in said structure, therefore, need the isolator of a kind of low-cost low performance of design, isolation gets final product about 8dB to 15dB.

Summary of the invention

In order to solve problems of the prior art, the utility model provides a kind of new free space isolator.

The technical solution of the utility model is specially: free space isolator comprises a slice polaroid and a slice quarter-wave plate that distributes along optical axis direction.

Wherein, when light positive to when transmission, the parallel part in the polarization direction of incident light and polaroid is by polaroid, the part vertical with the polarization direction is polarized sheet and absorbs, the light by polaroid forms circular polarization by quarter-wave plate.

Wherein, when the light backpropagation, circularly polarized light becomes linearly polarized light after by quarter-wave plate, and the polarization direction is vertical with the polaroid polarization direction.By polaroid, most of light is polarized sheet and absorbs again.

Compared with prior art, advantage of the present utility model and good effect are: free space isolator of the present utility model is applicable to can satisfy the isolator requirement in the not high light path of insulated degree requirement.But structure is simpler, and starting material are made and are more prone to, and the cost of isolator is reduced greatly.

Description of drawings

Fig. 1 is the forward index path of existing free space isolator.

Fig. 2 is the reverse optical path figure of existing free space isolator

Fig. 3 is the forward index path of free space isolator of the present utility model.

Fig. 4 is the reverse optical path figure of free space isolator of the present utility model.

Embodiment

Below in conjunction with the drawings and specific embodiments the utility model is done further detailed description.

Fig. 3 is the structural drawing of free space isolator of the present utility model.As shown in Figure 3, free space isolator comprises a slice polaroid 210 and a slice quarter-wave plate 220 that distributes along optical axis direction.In the utility model, as shown in Figure 3, when light positive to when transmission, part parallel with the polarization direction of polaroid 210 in the incident light is by polaroid 210, the part vertical with the polarization direction is polarized sheet 210 and absorbs, and the incident light by polaroid 210 forms behind the circularly polarized lights along optic path by quarter-wave plate 220.Please be simultaneously with reference to Fig. 4, because quarter-wave plate 220 has the characteristic that circularly polarized light is changed to linearly polarized light, therefore after light oppositely passes through quarter-wave plate 220, circularly polarized backlight becomes linearly polarized light, at this moment, the polarization direction of backlight is vertical with polaroid 210 polarization directions, and during by polaroid 210, most of backlight is polarized sheet 210 and absorbs.

At quarter-wave plate of the present utility model available four/n wave plate simultaneously, and n is that natural number (such as 5/4ths wave plates, 7/4ths wave plates etc.) replaces, and its structure is same as described above.Do not repeat them here.

Compared with prior art, advantage of the present utility model and good effect are: free space isolator of the present utility model is used in the not high light path of insulated degree requirement, can satisfy the isolator requirement.But structure is simpler, and starting material are made and are more prone to, and the cost of isolator is reduced greatly.

The above is the utility model most preferred embodiment only, is not be used to limiting scope of the present utility model, and all equivalences of doing according to the utility model claim change or modify, and are all the utility model and contain.

Claims

1. a free space isolator is characterized in that: comprise a polaroid and a quarter-wave plate; Wherein, after this quarter-wave plate is arranged on this polaroid along optical axis direction.

2. a free space isolator is characterized in that: comprise a polaroid and one or four/n wave plate, and n is natural number;

Wherein, after this four/n wave plate is arranged on this polaroid along optical axis direction.