KR19990018176U - Optical isolating device - Google Patents

Abstract

Disclosed is an optical isolating device having an improved structure to perform a plurality of optical isolator functions as one optical isolator core component.

The disclosed apparatus includes a first collimator for converting light rays emitted from the first optical fiber into parallel rays; Disposed sequentially on the optical path, the first polarizer for birefringent transmission of one incident light into the normal light and the abnormal light, a Faraday rotor for rotationally transmitting the incident light, and an inverted transmission of each of the incident normal light and the abnormal light An optical isolator comprising a second polarizer; A second collimator for focusing the light transmitted through the second polarizer to the second optical fiber; A third collimator disposed at a position different from the first collimator facing the light incident surface of the first polarizer and converging light rays emitted from the third optical fiber; A fourth collimator facing the light exit surface of the second polarizer and disposed at a different position from the second collimator, focusing the light emitted from the third collimator and output through the optical isolator to the fourth optical fiber; Characterized in that.

Description

Optical isolating device

The present invention relates to an optical isolating device which is employed between optical fibers to pass the light in one direction and blocks the light in the reverse direction. Specifically, the optical isolator performs a plurality of optical isolator functions with one optical isolator. The present invention relates to an optical isolating device having an improved structure.

A general optical isolating device includes an optical isolator for blocking a reverse ray beam by using polarization modes of light rays, and is disposed on each of the input and output surfaces of the optical isolator to input and output to the first and second optical fibers. First and second collimators for focusing light.

An optical isolator using a conventional polarization mode is located on an optical path between two optical fibers, which transmits light in a forward direction and blocks light in a reverse direction.

To this end, the optical isolator is composed of a birefringent crystal wedge-shaped first polarizer, a Faraday rotor, and a second polarizer. Therefore, the light rays traveling in the forward direction, that is, the light rays traveling in the order of the first polarizer, the Faraday rotor, and the second polarizer, are split into the normal light rays and the abnormal light rays parallel to each other while passing through the first and second polarizers. It is still directed to the optical fiber. Here, the optical path difference between the normal light beam and the abnormal light beam is defined as a walk-off, and when the walkoff is large, a time delay occurs between the normal light beam and the abnormal light beam, and polarization mode dispersion occurs.

Applicant has proposed an optical isolator using a polarization mode that can reduce the work-off without the addition of an optical component in consideration of the above-mentioned point, Korean Patent Application Nos. 96-18025, 96-80099, 96-80100 and , No. 97-9555.

The proposed optical isolator discloses the transmission of one channel, that is, one optical signal, by blocking the progress of the reverse light beam by making the forward light beam and the reverse light beam different from each other.

Therefore, in the optical amplifier such as EDFA, the optical isolator must be provided separately from the optical isolator for guiding in the traveling direction of the input light including the information, and the optical isolator for blocking the light incident from the reverse direction through the EDF. It became an obstacle to becoming angry.

The present invention has been made in view of the above-described point, and provides an optical isolating device that can realize a two-channel structure that can block reverse propagation for at least two light beams by using one optical isolator. The purpose is.

1 is a view showing an optical arrangement of the optical isolating device according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view for explaining a coupling relationship between the glass ferrule and the collimator shown in FIG.

<Description of Symbols for Main Parts of Drawings>

I ... First input beam II ... Second input beam 10 ... First optical fiber

20 ... second optical fiber 30 ... third optical fiber 40 ... fourth optical fiber

50 ... collimers 51, 53, 55, 57 ... 1st, 2nd, 3rd, 4th collimator

60 ... optical isolator 61 ... first polarizer

63.Faraday Rotator 65 ... 2nd Polarizer

70 ... glass parrule 75 ... holder

In order to achieve the above object, the optical isolating device according to the present invention,

A first collimator for converting light emitted from the first optical fiber into parallel light;

The first polarizer is arranged sequentially on the optical path, the first polarizer for birefringent transmission of one incident light into the normal light and the abnormal light, the Faraday rotor for rotationally transmitting the incident light and the reverse transmission of each of the incident normal light and the abnormal light An optical isolator comprising a second polarizer;

A second collimator for focusing the light transmitted through the second polarizer into a second optical fiber;

A third collimator facing the light incident surface of the first polarizer and disposed at a position different from the first collimator, for converging the light rays emitted from the third optical fiber;

A fourth collimator facing the light exit surface of the second polarizer and disposed at a different position from the second collimator, focusing the light emitted from the third collimator and output through the optical isolator to the fourth optical fiber; Characterized in that it has been included.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, an optical isolating device according to an embodiment of the present invention is disposed on an optical path between first to fourth optical fibers 10, 20, 30, and 40 for transmitting an optical signal. . The optical isolating device transmits light rays emitted from each of the first and third optical fibers 10 and 30 according to the polarization mode of the incident light beam to each of the second and fourth optical fibers 20 and 40. Light rays emitted from the second and fourth optical fibers 20 and 40 are blocked from traveling to the first and third optical fibers 10 and 30, respectively.

To this end, the optical isolating device, the first and third collimator to focus each of the first incident light (I) and the second incident light (II) transmitted from the first and third optical fiber (10) (30) Second and fourth collimators for focusing each of the light emitted from the optical isolator 60, the optical isolator 60, and the optical isolator 60 to the second and fourth optical fibers 20 and 40, respectively. 53) and 57).

The first and third collimators 51 and 53 are disposed to face the light incidence plane of the optical isolator 60, and focus light rays emitted from the first optical fiber 10 to be parallel rays.

The first and third collimators 51 and 55 may be disposed at different positions with respect to the light incident surface 61a of the optical isolator 60 to pass through each collimator 51 and 55. Make sure that the first and second incident rays I and II do not interfere with each other.

The optical isolator 60 is sequentially disposed on an optical path, and rotates the first polarizer 61 and the incident light to birefringently transmit the incident first and second incident light beams I and II. Faraday rotor 63 for transmitting and a second polarizer (65) for inverting the incident normal and abnormal light, respectively. The first polarizer 61 has a birefringent crystal wedge shape, and splits the first incident light I into the first and second rays I '(I "), and splits the second incident light II. It branches to 3rd and 4th light beam II '(II "). The first and third rays I ′ and II ′ are normal refractive indices of the first polarizer 61. n _o And the second and fourth rays I ″ and II ″ are extraordinary refractive indices of the first polarizer 61. n _e It is the abnormal light refracted by.

The first polarizer 61 has a predetermined crystal optical axis, and the first and third beams I 'and II' have a polarization direction parallel to the crystal optical axis of the first polarizer 61. The second and fourth rays I ″ and II ″ have a polarization direction perpendicular to the crystal optical axis.

Like the first polarizer 61, the second polarizer 65 has a birefringent crystal wedge shape and has a predetermined crystal optical axis having a direction different from that of the first polarizer 61. That is, the crystal optical axis of the second polarizer 65 is shifted by a predetermined angle in the direction opposite to the polarization rotation direction of the Faraday rotor 63 with respect to the crystal optical axis of the first polarizer 61.

The Faraday rotor 63 rotates the polarization direction of the incident light by a predetermined angle. Accordingly, the first and third rays I 'and II' passing through the Faraday rotor 63 are changed to abnormal rays, and the second and fourth rays I "and II" are normal. It turns into a ray.

The shapes of the first and second polarizers 61 and 65 are linearly symmetric about the Faraday rotor 63, and each of the first and second polarizers 61 and 65 has a lower surface than an upper surface thereof. Wide wedge shape.

The second collimator 53 is disposed to face the light exit surface 65a of the optical isolator 60, so that the first and second light beams I 'and I " emitted from the optical isolator 60 are disposed. The fourth collimator 57 is disposed to face the light exit surface 65a of the optical isolator 60, and is discharged from the optical isolator 60. The third and fourth rays II '(II ") are focused on the fourth optical fiber 40. Here, the second collimator 53 and the fourth collimator 57 are disposed at different positions to focus each of the incident first and second incident light beams I and II.

Here, each of the first to fourth optical fibers 10, 20, 30, 40 is preferably aligned with the glass ferrule 70, as shown in Figs.

In addition, each of the first to fourth collimators 51, 53, 55, and 57 may be a green (Graded Index) lens 50, as shown in FIG. 50 is coupled to the glass ferrule 70 by a holder 75.

Hereinafter, the operation of the optical isolating device according to the embodiment of the present invention with reference to FIG.

First, the first input light I transmitted through the first optical fiber 10 is incident on the light incident surface 61a of the first polarizer 61 while focusing on the first collimator 51. do. The incident first input light I is birefringed into the first light I ', which is a normal light, and the second light I ", which is an abnormal light, according to the crystal beam axis of the first polarizer 61. It is directed toward the second collimator 53 via the Faraday rotor 63 and the second polarizer 65. Here, the first ray I 'is the direction of rotation polarization of the Faraday rotor 63 and According to the crystal optical axis of the second polarizer 65, it is converted into abnormal light, and the second light I "is converted into normal light. Therefore, the two light beams I 'and I "are incident on the second collimator 53 in parallel with each other without having a mutual optical path difference. The incident light is focused while passing through the second collimator 53. And is output through the second optical fiber 20.

The second incident light beam II input through the third optical fiber 30 is focused by the third collimator 55 and then the fourth optical fiber via the optical isolator 60 and the fourth collimator 57. 40 is passed. Since the change of the second incident light II is substantially the same as the first incident light I described above, a detailed description thereof will be omitted.

Meanwhile, the light rays (not shown) incident from the second and fourth optical fibers 20 and 40 toward the optical isolator 60 are first and second by the first and second polarizers 61 and 65. Proceeds in a path different from the path of the second input light (I) (II), it is blocked from being transmitted to each of the first and third optical fibers (10) (30).

As described above, the optical isolating device according to the embodiment of the present invention configured to guide the traveling direction of the light for each of the first incident light and the second incident light through one optical isolator. Therefore, when adopted in an optical amplifier that requires two optical isolator, it can be replaced by one optical isolator, it is possible to simplify the optical configuration, reduce the number of parts and improve the assembly.

Although the present invention has been described with respect to two incident light beams as shown in FIG. 2, this is merely an example, and further includes a collimator corresponding to each of three or more input light beams, thereby relocating them to one or more light beams. The optical isolator can replace the role of multiple optical isolators.

Claims (4)

A first collimator for converting light emitted from the first optical fiber into parallel light; Disposed sequentially on the optical path, the first polarizer for birefringent transmission of one incident light into the normal light and the abnormal light, a Faraday rotor for rotationally transmitting the incident light, and an inverted transmission of each of the incident normal light and the abnormal light An optical isolator comprising a second polarizer; A second collimator for focusing the light transmitted through the second polarizer into a second optical fiber; A third collimator facing the light incident surface of the first polarizer and disposed at a position different from the first collimator, for converging the light rays emitted from the third optical fiber; A fourth collimator facing the light exit surface of the second polarizer and disposed at a different position from the second collimator, focusing the light emitted from the third collimator and output through the optical isolator to the fourth optical fiber; Optical isolating device, characterized in that it comprises a. The optical isolating device according to claim 1, wherein each of the first and second polarizers is mutually symmetrical with respect to the Faraday rotor in a birefringent crystal wedge shape having a lower surface than that of the upper surface. The optical isolating device according to claim 1 or 2, wherein a glass ferrule is arranged at an end of each of the first to fourth optical fibers to align the position thereof. The optical isolating device according to claim 1, wherein each of the first to fourth collimators is a green lens.