CN201063082Y

CN201063082Y - Polarization correlative isolater for free space

Info

Publication number: CN201063082Y
Application number: CNU200720007963XU
Authority: CN
Inventors: 施向华; 凌吉武; 徐云兵
Original assignee: Photop Technologies Inc
Current assignee: Photop Technologies Inc
Priority date: 2007-08-17
Filing date: 2007-08-17
Publication date: 2008-05-21
Anticipated expiration: 2017-08-17

Abstract

The utility model discloses a free-space polarized light isolator, comprising a birefraction crystalloid, a 45 degrees Faraday rotator with and a polarimeter. The optical axis of the birefraction crystalloid makes the light in different polarization state walk off horizontally after entering the birefraction crystalloid, the optical axis of the polarimeter and the birefraction crystalloid are at an angle of 45 degrees; by adopting the structure, when the light is transmitted in forward direction, a linear polarized light is able to go into the polarimeter successfully after entering through the birefraction crystalloid and the 45 degrees Faraday rotator; when the light is transmitted in reverse direction, the direction of polarization state of light is changed to be vertical to the original polarization direction of the input light after entering the Faraday rotator through the agency thereof, and then the light enters the polarizing beam splitter which is composed of the birefraction crystalloid, thereby the direction of transmission of the light has a certain angle with the original direction and making the return light and input light move horizontally so as to be unable to enter into the inside of a luminous element, therefore, playing the role of the isolator. Meanwhile the birefraction crystalloid has low cost, thereby reducing the price greatly.

Description

A kind of polarization of free space isolator of being correlated with

Technical field

The utility model relates to the optical fiber communication technology field, relates in particular to a kind of relevant isolator of polarization that is applied to the free space in the optical transceiver module.

Background technology

Optoisolator is one of micro-optical device that is applied to the earliest optical communication, and it mainly acts on is exactly that the light of forward transmitted is passed through, and the light of reverse transfer is isolated.Isolator is divided in line style and free space type two big classes as if the environment by its use, isolator also can be by polarization relevant and polarization irrelevant divide, all have for two kinds at line style and free space type and to comprise, the polarization relationship type isolator of general free space type is used some more, mainly is used in the encapsulation of active device.

The isolator of being correlated with of free space polarization as shown in Figure 1, it comprises polarizer 1 (generally being 0 ° of Polarcor), 45 ° of Faraday rotators 3 (being generally BIG or yig crystal), polarizer 2 (material is with polarizer 1, and optical axis position is 45 ° relatively).When forward transmitted, by entering polarizer 2 behind polarizer 1 and 45 ° of Faraday rotators 3, because the optical axis of polarizer 2 just is 45 ° of directions, polarized light is just as entering the reception collimating apparatus through a flat board from the emission of incident collimating apparatus for light; When the light reverse transfer, because the effect of Faraday rotator 3 makes by behind the Faraday rotator 3, the polarization state of light direction is vertical with the optical axis of polarizer 1, therefore during reverse transfer, because light echo polarization state direction is vertical with the optical axis direction of Polarcor, make light echo all be isolated out, light can not enter collimating apparatus, plays the effect that light is isolated.Because the price comparison of polarizer (0 ° of Polarcor and 45 ° of Polarcor) is expensive, so cost is than higher.

Summary of the invention

The purpose of this utility model has been to provide a kind of polarization of lower-cost free space relevant isolator.

For achieving the above object, the relevant isolator of the utility model polarization comprises a birefringece crystal, 45 ° of Faraday rotators and 45 ° of polarizers, wherein the direction of birefringece crystal optical axis the light of different polarization states is entered laterally walk behind the birefringece crystal from, the optical axis of polarizer and the placement at 45 of the optical axis of birefringece crystal.

The optical axis of birefringece crystal has angle in the plane of incidence and with the surface of birefringece crystal, perhaps be parallel to refractive surface and vertical with the plane of incidence, or make the light that incides the different polarization states in the birefringece crystal laterally walk from angle, it has two reflectings surface.

After adopting said structure, light positive is when transmission, and the line style polarized light enters polarizer after by birefringece crystal and 45 ° of Faraday rotators, because the optical axis of polarizer is 45 ° of directions, polarization luminous energy passes through smoothly; When the light reverse transfer, because the effect of Faraday rotator, make by the polarization state direction behind the Faraday rotator vertical with original input polarisation of light direction, again behind the polarization beam apparatus through the birefringece crystal formation, its direction of propagation and former direction have certain angle, make return light and incident light generation transversal displacement, return light can not enter light-emitting component inside, play the effect of isolator, therefore the relevant isolator of this polarization also can be described as the displacement isolator, the linearly polarized light forward that promptly makes light-emitting component send passes through, and oppositely ends.

Description of drawings

Below in conjunction with accompanying drawing the utility model is described in further detail:

Fig. 1 is the principle of work synoptic diagram of the relevant isolator of existing free space polarization;

Fig. 2 is the structural representation of the relevant isolator of the utility model polarization;

Fig. 3 is the light path principle synoptic diagram of the relevant isolator of the utility model polarization;

Fig. 4 is the concrete enforcement structural representation of the relevant isolator of the utility model polarization;

Embodiment

See also Fig. 2 or shown in Figure 3, the relevant isolator of the utility model polarization comprises a birefringece crystal 101,45 ° of Faraday rotators 102 and 45 ° of polarizers 103, wherein the direction of birefringece crystal 101 optical axises the light of different polarization states is entered laterally walk behind the birefringece crystal 101 from, the optical axis of birefringece crystal 101 has angle in the plane of incidence and with the surface of birefringece crystal 101, perhaps be parallel to refractive surface and vertical with the plane of incidence, or make the light that incides the different polarization states in the birefringece crystal 101 laterally walk from angle, it has two reflectings surface, and optical axis direction that can be by adjusting birefringece crystal 101 and thickness are controlled return light and depart from laterally walking to off normal and moving of forward light when the outgoing birefringece crystal.The placement at 45 of the optical axis of the optical axis of polarizer 103 and birefringece crystal 101.Birefringece crystal 101 can combine by the mode that optics contacts according to certain angle with 45 ° of Faraday rotators 102 and polarizer 103, or by tackifier it is combined.

For easy to process, the optical axis that can make birefringece crystal in the plane of incidence and with plane of crystal angle at 45, make the optical axis direction of 45 ° of polarizers 103 and the optical axis direction (from optical direction) at 45 of birefringece crystal 101, and 45 ° of Faraday rotators are clipped in the middle.Adopt said structure, after a polarized light impinges perpendicularly on birefringece crystal 101 surfaces, in birefringece crystal 101, propagate with o light, o light polarization direction when outgoing should with the optical axis of polarizer 103 angle at 45,45 ° have been rotated by 45 ° of Faraday rotators, 102 back line polarisations, again through 103 outputs of 45 ° of polarizers.Return light becomes linearly polarized light behind polarizer 103, again through behind 45 ° of Faraday rotators 102,90 ° deflection has taken place in return polarization state of light direction when transmitting than forward, entering birefringece crystal 101 backs propagates with e light, there is a deviation angle degree its direction of propagation than the direction of propagation in forward time, because birefringece crystal has certain thickness, light just has lateral excursion after propagating a segment distance like this, return light can not be back to light-emitting component along former road again, has played the effect of isolating.

See also shown in Figure 4ly, the concrete enforcement structure of the relevant isolator of the utility model: general LD1 output light all is polarized light, the relevant isolator of above-mentioned polarization is put into light path after, light return from subsequent optical path just can be isolated.

Claims

1. the relevant isolator of the polarization of a free space, comprise a birefringece crystal, 45 ° of Faraday rotators and a polarizer, it is characterized in that: the direction of its birefringece crystal optical axis the light of different polarization states is entered laterally walk behind the birefringece crystal from, the optical axis of polarizer and the placement at 45 of the optical axis of birefringece crystal.

2. the relevant isolator of the polarization of a kind of free space according to claim 1, it is characterized in that: the optical axis of its birefringece crystal has angle in the plane of incidence and with plane of crystal, perhaps optical axis is parallel to refractive surface and vertical with the plane of incidence, or make the light that incides the different polarization states in the birefringece crystal laterally walk from angle, it has two reflectings surface.

3. the relevant isolator of the polarization of a kind of free space according to claim 1 is characterized in that: impinge perpendicularly on the birefringece crystal the o light polarization direction of light when outgoing should with the optical axis of polarizer angle at 45.

4. the relevant isolator of the polarization of a kind of free space according to claim 1, it is characterized in that: its birefringece crystal, 45 ° of Faraday rotators combine by the mode that optics contacts with polarizer, or by tackifier it are combined.