CN210348115U

CN210348115U - Miniaturized optical circulator

Info

Publication number: CN210348115U
Application number: CN201920771330.9U
Authority: CN
Inventors: 林蕊; 林立良; 吴季; 王城强; 陈伟; 张星; 陈秋华
Original assignee: Fujian Castech Crystals Inc
Current assignee: Fujian Castech Crystals Inc; Castech Inc
Priority date: 2019-05-27
Filing date: 2019-05-27
Publication date: 2020-04-17
Anticipated expiration: 2029-05-27

Abstract

The utility model discloses a miniaturized light circulator contains following component: the polarization beam splitter, the first polarization state converter, the birefringent crystal a, the second polarization state converter, the optical path compensator, the lambda/2 wave plate and the birefringent crystal b. The first polarization converter and the second polarization converter are both composed of 45-degree Faraday rotation plates and lambda/2 wave plates, and can enable the polarization direction of linearly polarized light transmitted in the forward direction to rotate by pi/2 clockwise and enable the polarization direction of linearly polarized light transmitted in the reverse direction to be unchanged. Wherein the 45-degree Faraday rotator is made of a material which can rotate the polarization state of light without a magnetic field. Compared with a conventional optical circulator, the optical circulator is greatly reduced in size without using a magnet set, an optical signal input from a T1 port is linearly polarized light (horizontal polarized light), the linearly polarized light (vertical polarized light) is output from a T2 port to form a first optical path, and an optical signal input from a T2 port is polarization-independent light, and the polarization-independent light is output from a T3 port to form a second optical path.

Description

Miniaturized optical circulator

Technical Field

The utility model relates to an optical circulator, in particular to a miniaturized optical circulator.

Background

An optical circulator is a multi-port input-output non-reciprocal optical device, generally having three ports, and its function is to realize transmission of optical signals from a first port to a second port, where signals of the second port cannot be output from the first port, but can realize transmission from the second port to a third port.

Optical circulators are commonly used in optical communication systems and optical measurement systems. In the field of optical communication, the use of the optical circulator enables a common dual-port optical transceiver module to realize single-fiber bidirectional transmission, and is an essential device when a dual-port dual-fiber is changed into single-fiber bidirectional transmission. However, the optical circulator in the prior art is large in size and difficult to integrate into a small-sized assembly, which seriously hinders the use of the device.

Disclosure of Invention

The utility model aims at providing a miniaturized optical circulator, the utility model discloses an optical circulator has used the less optical assembly of volume, can integrate same small-size optical assembly, and the cost very reduces to it is bulky to have solved current optical circulator, should not integrate, problem with high costs.

In order to achieve the above object, the present invention provides a miniaturized optical circulator, along an optical axis, the following elements arranged in sequence:

a polarization beam splitter which passes all of the incident horizontally polarized light or reflects vertically polarized light;

the first polarization state converter consists of a 45-degree Faraday rotation plate and a lambda/2 wave plate;

the birefringent crystal a outputs the incident horizontal polarized light along the original optical path or divides an incident polarization-independent light beam into horizontal polarized light and vertical polarized light;

the second polarization state converter consists of a 45-degree Faraday rotation plate and a lambda/2 wave plate;

the optical path compensation plate does not change the polarization state of light and only provides an optical path;

the included angle between the optical axis of the wave plate and the edge of the wave plate is 45 degrees, and the horizontal polarized light is changed into the vertical polarized light or the vertical polarized light is changed into the horizontal polarized light;

the birefringent crystal b divides one polarization-independent light beam into horizontal polarized light and vertical polarized light, or combines the horizontal polarized light and the vertical polarized light into one polarization-independent light beam;

the method is characterized in that: an optical signal input from a T1 port is linearly polarized light (horizontal polarized light) and sequentially passes through a polarization beam splitter, a first polarization state converter and a birefringent crystal a, the linearly polarized light (vertical polarized light) is output from a T2 port to form a first optical path, and an optical signal input from a T2 port is polarization-independent light and sequentially passes through the birefringent crystal a, the first polarization state converter, a second polarization state converter, the polarization beam splitter, an optical path compensation plate, a lambda/2 wave plate and the birefringent crystal b, and the polarization-independent light is output from a T3 port to form a second optical path.

The 45-degree Faraday rotator is made of a material which can rotate the polarization state of light without a magnetic field.

The beneficial effects of the utility model are that, reduced the volume of current optical circulator, had the possibility of integrating in small-size optical assembly.

Drawings

FIG. 1 is a schematic structural view of the optical circulator of the present invention;

fig. 2 is a schematic diagram of a transmission optical path from port T1 to port T2 of the optical circulator of the present invention;

fig. 3 is a schematic diagram of the transmission optical path from port T2 to port T3 of the optical circulator of the present invention;

fig. 4 is a schematic diagram of a transmission optical path from port T3 to port T2 of the optical circulator of the present invention;

fig. 5 is a schematic diagram showing the position of the optical axis of the λ/2 wave plate 7.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1, the optical circulator of the present invention includes a polarization beam splitter 1, a first polarization converter (45 degree faraday rotator 2, λ/2 wave plate 3), a birefringent crystal a4, a second polarization converter (45 degree faraday rotator 5, λ/2 wave plate 6), an optical path compensator 8, a λ/2 wave plate 7, and a birefringent crystal b 9.

Fig. 2 is the optical circulator port T1 to port T2 transmission light path schematic diagram of the utility model, the polarization state is unchangeable after the horizontal polarization light that incides from port T1 passes through polarization beam splitter 1, after subsequently passing through the first polarization state converter that comprises 45 degrees faraday rotator 2 and lambda/2 wave plate 3, light polarization direction becomes perpendicular polarized light along clockwise rotation pi/2, and perpendicular polarized light is unchangeable through birefringent crystal a4 polarization state along former light path subsequently, exports from port T2.

Fig. 3 is a schematic diagram of a transmission optical path from port T2 to port T3 of the optical circulator of the present invention, in which a polarization-independent light beam incident from port T2 is divided into a linearly polarized light beam with a horizontal polarization and a vertically polarized light beam after passing through birefringent crystal a. The horizontally polarized light enters a second polarization state converter consisting of a 45-degree Faraday rotator 5 and a lambda/2 wave plate 6, and the vertically polarized light enters a first polarization state converter consisting of a lambda/2 wave plate 3 and a 45-degree Faraday rotator 2 due to the nonreciprocity of the Faraday rotator and the reciprocity of the lambda/2 wave plate; the horizontal polarized light passes through a 45-degree Faraday rotator 5 and then rotates clockwise by 45 degrees, and then passes through a lambda/2 wave plate 6 and rotates clockwise by 45 degrees again to become vertical polarized light; the vertically polarized light passes through the λ/2 wave plate 3 and then rotates 45 degrees counterclockwise, and then passes through the 45-degree faraday rotator 2 and then rotates 45 degrees clockwise or is vertically polarized light (for convenience of description, the vertically polarized light converted from the horizontally polarized light in this text is referred to as vertically polarized light 1, and the vertically polarized light with the unchanged polarization state is referred to as vertically polarized light 2), then the two vertically polarized light beams are reflected by the polarization splitting dielectric film on the oblique side and propagate upward when entering the polarization beam splitter 1, the vertically polarized light 1 propagates upward through the optical path compensator 8 and then enters the birefringent crystal b9 with the unchanged polarization state, the vertically polarized light 2 propagates upward through the λ/2 wave plate 7 and then rotates to become horizontally polarized light (the included angle between the vertically polarized light 2 and the optical axis of the λ/2 wave plate 7 is 45 degrees), and then enters the birefringent crystal b9, and then the horizontally polarized light and the vertically polarized light are combined into a polarization independent light beam by the birefringent crystal b 9.

Fig. 4 is a schematic diagram of a transmission optical path from port T3 to port T2 of the optical circulator of the present invention, in which a polarization-independent light beam incident from port T3 is divided into a linearly polarized light beam with a horizontal polarization and a vertically polarized light beam after passing through birefringent crystal b. The vertically polarized light passes through the optical path compensation plate 8, enters the polarization beam splitter 1 without changing its polarization state, and is reflected by the polarization splitting dielectric film on the oblique side to propagate rightward, and the horizontally polarized light passes through the λ/2 wave plate 7 and then rotates to become vertically polarized light (for convenience of description, the vertically polarized light with the unchanged polarization state is referred to as vertically polarized light 1, and the vertically polarized light converted from the horizontally polarized light is referred to as vertically polarized light 2 in this text), enters the polarization beam splitter 1, and is reflected by the polarization splitting dielectric film on the oblique side to propagate rightward. The vertically polarized light 1 then passes through a lambda/2 wave plate 6 and rotates 45 degrees anticlockwise, passes through a 45-degree Faraday rotator 5 and rotates 45 degrees clockwise, so that the polarization state is unchanged or the vertically polarized light enters a birefringent crystal a and then is transmitted along an original optical path and output; after being reflected, the vertically polarized light 2 is rotated by 45 degrees clockwise through the 45-degree Faraday rotator 2 and is rotated by 45 degrees clockwise through the lambda/2 wave plate 3, so that the vertically polarized light becomes horizontally polarized light, enters the birefringent crystal a and is deflected and propagated downwards, and finally the two beams of light are not synthesized and do not enter the port T2.

Fig. 5 is a schematic diagram of the position of the optical axis of the λ/2 wave plate 7, where an angle between the optical axis of the λ/2 wave plate 7 and the edge thereof is 45 degrees, so that the horizontally polarized light can be rotated by 90 degrees to become vertically polarized light, and the vertically polarized light can be rotated by 90 degrees to become horizontally polarized light.

The above description is only for the purpose of illustration of the embodiments of the present invention, and not for the purpose of limitation, and any insubstantial modifications are intended to be covered by the claims of the present invention.

Claims

1. A miniaturized optical circulator, the following components are arranged in sequence along an optical axis: the polarization beam splitter, the first polarization state converter, the birefringent crystal a, the second polarization state converter, the optical path compensator, the lambda/2 wave plate and the birefringent crystal b. The method is characterized in that: the optical signal input by the port (T1) is horizontally polarized light, and sequentially passes through the polarization beam splitter and the first polarization state converter, the birefringent crystal a outputs vertically polarized light from the port (T2) to form a first optical path, and the optical signal input by the port (T2) is polarization-independent light, and sequentially passes through the birefringent crystal a, the first polarization state converter, the second polarization state converter, the polarization beam splitter, the optical path length compensator, the λ/2 wave plate, and the birefringent crystal b outputs polarization-independent light from the port (T3) to form a second optical path, wherein the optical path length compensator does not change the polarization state of light and only provides an optical path.

2. A miniaturized optical circulator as claimed in claim 1, further comprising: the 45-degree Faraday rotator is made of a material which can rotate the polarization state of light without a magnetic field.