CN1928686A - Full optical fiber cross device - Google Patents

Abstract

The new full-fiber wavelength interleaving device comprises: based on HBF Sagnac interferometer, a circulator, a coupler, the HBF, a polarization controller, a tuning mechanism for middle-channel wavelength, and the monomode fiber. This invention changes the product deltandeltaL of HBF equivalent refractive index difference and length variation to shift the transmission spectrum of the interleaving device, and works reliable with low cost.

Description

Novel full optical fiber cross device

[technical field]

The present invention relates to cross device, particularly a kind ofly can realize having polarization irrelevant, flat-top spectrum shape and the fine-tuning novel full optical fiber cross device of centre wavelength based on HBF Sagnac interferometer.

[background technology]

Cross device is one of Primary Component of dwdm system, can be used for improving the dwdm system transmission capacity, realizes system upgrade, wavelength route etc.Because polarization state of light is at random in ordinary optic fibre, so desirable optical filter should have polarization independence; High in addition side mode suppression ratio, centre wavelength is fine-tuning and to have performance such as flat-top spectrum shape also be vital for dwdm system.The scheme that realizes the optical wavelength interleaver at present mainly contains based on Mach-Zehnder (Mach-Zehnder) interferometer type, arrayed waveguide grating type, crystal birefringence type cross device etc.Mach-Zehnder (Mach-Zehnder) interferometer type cross device can be accomplished full optical fiber designs in theory, the channel good uniformity, but temperature stability is poor, and high for the splitting ratio requirement of two arm optical path differences and coupling mechanism, be difficult to practicability; Arrayed waveguide grating type cross device transmission spectral pattern is controlled easily, can be designed to many group outputs, and shortcoming is that isolation is not high, and temperature stability is poor, the dispersity height; Crystal birefringence type cross device can flexible design satisfy the different channels space requirement, but Polarization Dependent Loss is bigger.

[summary of the invention]

Purpose of the present invention is intended to for overcoming the deficiencies in the prior art, and provide a kind of novel full optical fiber cross device, this novel full optical fiber cross device utilizes the 3dB photo-coupler that incident light is divided into two bundles, make it enter high birefringence optical fiber respectively, after transmitting a week in opposite directions along optical fiber, return the 3dB photo-coupler and meet, produce and interfere.

The present invention be address the above problem the scheme that is adopted be the design a kind of novel full optical fiber cross device.It comprises: circulator, 3dB photo-coupler, Polarization Controller, high birefringence optical fiber and wavelength tuning mechanism of channel center and single-mode fiber, the input port Port1 that it is characterized in that said dense wave division multipurpose light signal is connected with the port (a) of circulator (1), the port (b) of circulator (1) is connected with the port (a) of 3dB photo-coupler (2), and the port (c) of circulator (1) is connected with output port Port2; The port (b) of said 3dB photo-coupler (2) is connected with an end of first Polarization Controller (3), the other end of first Polarization Controller (3) is connected with an end of first high birefringence optical fiber (6), the other end of first high birefringence optical fiber (6) is connected with an end of second Polarization Controller (4), the other end of second Polarization Controller (4) is connected with an end of second high birefringence optical fiber (7), the other end of second high birefringence optical fiber (7) is connected with the 3rd Polarization Controller (5), the other end of the 3rd Polarization Controller (5) is connected with an end of the 3rd high birefringence optical fiber (8), and the other end of the 3rd high birefringence optical fiber (8) is connected with the port (c) of 3dB photo-coupler (2); And the part of the 3rd high birefringence optical fiber (8) is connected with wavelength tuning mechanism of channel center (9); And the port (d) of coupling mechanism (2) is connected with output port Port3.

The present invention utilizes the 3dB photo-coupler that incident light is divided into two bundles, make it enter HBF respectively, transmit a week in opposite directions along optical fiber after, return the 3dB photo-coupler and meet, produce and interfere, the Sagnac ring structure that this paper proposes has obtained higher side mode suppression ratio when having realized flat-top; Utilize wavelength tuning mechanism of channel center, make the equivalent refraction rate variance of pasting the high birefringence optical fiber on it and the long-pending Δ n Δ L of the length variations amount of birefringence fiber that corresponding change take place, thereby the transmission spectrum that makes cross device produces phase shift, and the size that puts on the semi-girder lateral stress by change is controlled the position with tuning wavelength.Theoretical analysis shows with experimental result: (1) this cross device is compared with the interleaver that common HBF Sagnac interferometer constitutes and is being obtained improvement significantly aspect flat-top and the side mode suppression ratio two.(2) the channel center's wavelength tuning of the long scope of all-wave and the switching of odd-even channel have been realized.This invention is simple in structure, easy to adjust, with low cost, steady operation at normal temperatures.

[description of drawings]

Fig. 1 is novel full optical fiber cross device synoptic diagram;

Fig. 2 is channel center's wavelength tuning structural scheme of mechanism;

Fig. 3 is the transmission spectrogram of novel full optical fiber cross device.

Among the figure: 1. circulator; 2.3dB photo-coupler; 3. first Polarization Controller; 4. second Polarization Controller; 5. the 3rd Polarization Controller; 6. first high birefringence optical fiber; 7. second high birefringence optical fiber; 8. the 3rd high birefringence optical fiber; 9. channel center's wavelength tuning mechanism; 10. semi-girder; 11. fixed flat planar; 12. displacement stepping mechanism; 13. single-mode fiber.

Be described in detail with reference to accompanying drawing below in conjunction with embodiments of the invention.

[embodiment]

The present invention-based on the cross device of HBF Sagnac interferometer, it comprises: circulator, photo-coupler, high birefringence optical fiber (HBF), Polarization Controller (PC), wavelength tuning mechanism of channel center and with interconnective single-mode fiber of each device etc.Be characterized in:

Dense wave division multipurpose (Dense Wavelength-Division-MultiplexerDWDM) optical signals input port Port1 inputs to the port a of circulator 1, the port b of circulator 1 is connected with the port a of 3dB photo-coupler 2, the port c of circulator 1 links to each other with output port Port2, and output port Port2 is the strange channel output terminal of DWDM light signal.

The port b of 3dB photo-coupler 2 is connected with first Polarization Controller 3, the other end of first Polarization Controller 3 is connected with an end of first high birefringence optical fiber 6, the other end of first high birefringence optical fiber 6 is connected with second Polarization Controller 4, the other end of second Polarization Controller 4 is connected with an end of second high birefringence optical fiber 7, the other end of second high birefringence optical fiber 7 is connected with the 3rd Polarization Controller 5, the other end of the 3rd Polarization Controller 5 is connected with an end of the 3rd high birefringence optical fiber 8, and the 3rd high birefringence optical fiber 8 other ends are connected with the port c of 3dB photo-coupler 2.The port d of 3dB photo-coupler 2 links to each other with output port Port3, and output port Port3 is the even channel output terminal of DWDM light signal.Connection between the integral device connects with single-mode fiber (13).

Three sections high birefringence optical fiber 6,7,8 length ratios are 2: 2: 1.

Wavelength tuning mechanism of channel center (9) is by the semi-girder that is connecting the 3rd high birefringence optical fiber (8) (10), the fixed flat planar (11) that contact with the top, outer end of semi-girder, and can apply displacement stepping mechanism (12) composition that lateral stress changes the amount of deflection of beam.Wherein: on semi-girder (10) static housing; Bonding the 3rd high birefringence optical fiber (8) along the axis of semi-girder; Displacement stepping mechanism (12) be one can revolve fixed flat planar (11) screw, the top is the screw of nut.

By the precession of lateral shift stepping mechanism 12, can carry out the fine tuning of channel center's wavelength.Semi-girder (10) cross section of wavelength tuning mechanism of channel center (9) is a rectangle, can use the metal or the nonmetallic materials of high rigidity energy, as manganese steel, organic glass.

Principle of the present invention is that input light at first passes through circulator, then is divided into two bundles by the 3dB photo-coupler and enters HBF respectively, pass a week in opposite directions along optical fiber after, return the 3dB photo-coupler and meet, produce and interfere.Polarization Controller PC is used to adjust the angle of the input light between centers fast with it of HBF.When the coupling coefficient of coupling mechanism was 0.5, the reflection of the cross device of proposition and transmission spectrum function were:

R＝1-(A ₁+A ₂+A ₃+A ₄)

T＝(A ₁+A ₂+A ₃+A ₄) ²

Wherein $A_1=\sin ({\mathrm{\θ}}_4-{\mathrm{\θ}}_1)\cos {\mathrm{\θ}}_2\cos {\mathrm{\θ}}_3\cos (\frac{{\mathrm{\β}}_1}{\mathrm{\λ}}+\frac{{\mathrm{\β}}_2}{\mathrm{\λ}}+\frac{{\mathrm{\β}}_3}{\mathrm{\λ}})$

$A_2=\cos ({\mathrm{\θ}}_4-{\mathrm{\θ}}_1)\cos {\mathrm{\θ}}_2\sin {\mathrm{\θ}}_3\cos (\frac{{\mathrm{\β}}_1}{\mathrm{\λ}}+\frac{{\mathrm{\β}}_2}{\mathrm{\λ}}-\frac{{\mathrm{\β}}_3}{\mathrm{\λ}})$

$A_3=-\sin ({\mathrm{\θ}}_4-{\mathrm{\θ}}_1)\sin {\mathrm{\θ}}_2\sin {\mathrm{\θ}}_3\cos (\frac{{\mathrm{\β}}_1}{\mathrm{\λ}}-\frac{{\mathrm{\β}}_2}{\mathrm{\λ}}+\frac{{\mathrm{\β}}_3}{\mathrm{\λ}})$

$A_4=\cos ({\mathrm{\θ}}_4-{\mathrm{\θ}}_1)\sin {\mathrm{\θ}}_2\cos {\mathrm{\θ}}_3\cos (\frac{{\mathrm{\β}}_1}{\mathrm{\λ}}-\frac{{\mathrm{\β}}_2}{\mathrm{\λ}}-\frac{{\mathrm{\β}}_3}{\mathrm{\λ}})$

The DWDM light signal inputs to circulator 1 through input port Port1, input light enters 3dB photo-coupler 2,3dB photo-coupler 2 will import light be divided into two transmit a week in opposite directions along loop after, after the two-beam of getting back to 3dB photo-coupler 2 interferes, d end by 3dB photo-coupler 2 is exported transmitted light through output port Port3, a holds the b end of output reflection light to circulator 1, and is held through output port Port2 output reflection light by the c of circulator 1.Polarization Controller 3,4 and 5 is used to regulate the angle of the fast between centers of two direction incident lights and high birefringence optical fiber 6,7,8, regulates Polarization Controller the polarization direction of light wave is rotated.By above scheme, can realize staggered, the characteristics such as transmission spectrum is even at interval with reflectance spectrum flat-top, output wavelength, side mode suppression ratio height of odd-even channel.Output spectrum is seen Fig. 3.

Circulator 1 is used for input light is separated with reflection output light; 3dB photo-coupler 2 has four port a, b, c and d at least, the light of outside input is divided into two transmits in opposite directions along loop on the one hand, makes on the other hand to transmit the two-beam of getting back to 3dB photo-coupler 2 after a week in opposite directions and interfere; The angle of the fast between centers of three Polarization Controller 3,4,5 scalable, two direction incident lights and high birefringence optical fiber 6,7,8; High birefringence optical fiber 6,7,8 will satisfy certain ratio: 2: 2: 1, be used to make two polarized components by its light to produce phase differential; Wavelength tuning mechanism of channel center is used for the fine setting of cross device centre wavelength.

Circulator can be any optical circulator that optical fiber or optical crystal are made, and should have three ports at least

Photo-coupler is and the 3dB photo-coupler of DWDM phase adjust signal that it has four ports at least.

Polarization Controller can be any polarization rotator of scalable polarization state of light.

But wavelength tuning mechanism of channel center stress application by applying the amount of deflection that lateral stress changes beam, is regulated the position of channel center wavelength with this in high birefringence optical fiber.

Cross device of the present invention can be worked at normal temperatures.

Claims (9)

1, a kind of novel full optical fiber cross device, comprise: circulator, 3dB photo-coupler, Polarization Controller, high birefringence optical fiber and wavelength tuning mechanism of channel center, and connection single-mode fiber, the input port Port 1 that it is characterized in that said dense wave division multipurpose light signal is connected with the port (a) of circulator (1), the port (b) of circulator (1) is connected with the port (a) of 3dB photo-coupler (2), and the port (c) of circulator (1) is connected with output port Port 2; The port (b) of said 3dB photo-coupler (2) is connected with an end of first Polarization Controller (3), the other end of first Polarization Controller (3) is connected with an end of first high birefringence optical fiber (6), the other end of first high birefringence optical fiber (6) is connected with an end of second Polarization Controller (4), the other end of second Polarization Controller (4) is connected with an end of second high birefringence optical fiber (7), the other end of second high birefringence optical fiber (7) is connected with the 3rd Polarization Controller (5), the other end of the 3rd Polarization Controller (5) is connected with an end of the 3rd high birefringence optical fiber (8), and the other end of the 3rd high birefringence optical fiber (8) is connected with the port (c) of 3dB photo-coupler (2); And the part of the 3rd high birefringence optical fiber (8) is connected with wavelength tuning mechanism of channel center (9); And the port (d) of coupling mechanism (2) is connected with output port Port 3.

2, novel full optical fiber cross device according to claim 1 is characterized in that the length ratio of said first high birefringence optical fiber (6), second high birefringence optical fiber (7) and the 3rd high birefringence optical fiber (8) is 2: 2: 1.

3, novel full optical fiber cross device according to claim 1 and 2, it is characterized in that wavelength tuning mechanism of said channel center (9) is by the semi-girder that is connecting the 3rd high birefringence optical fiber (8) (10), the fixed flat planar (11) that contacts with the top, outer end of semi-girder, and can apply displacement stepping mechanism (12) composition that lateral stress changes the amount of deflection of beam.

4, novel full optical fiber cross device according to claim 3 is characterized in that on said semi-girder (10) static housing; Bonding the 3rd high birefringence optical fiber (8) along the axis of semi-girder; Displacement stepping mechanism (12) be one can revolve fixed flat planar (11) screw, the top is the screw of nut.

5, novel full optical fiber cross device according to claim 4 is characterized in that semi-girder (10) cross section of wavelength tuning mechanism of said channel center (9) is a rectangle, uses the metal or the nonmetallic materials of high rigidity energy, as manganese steel, organic glass.

6, novel full optical fiber cross device according to claim 3 is characterized in that said circulator is the optical circulator that optical fiber or optical crystal are made.

7, novel full optical fiber cross device according to claim 3 is characterized in that said coupling mechanism is the 3dB photo-coupler with the DWDM phase adjust signal.

8, novel full optical fiber cross device according to claim 3 is characterized in that said Polarization Controller, is the polarization rotator of scalable polarization state of light.

9, according to claim 4 or 5,6,7 described novel full optical fiber cross devices, it is characterized in that said Polarization Controller, is the polarization rotator of scalable polarization state of light.

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