CN103091787B - Adjustable optical attenuator and adjustable optical attenuator wavelength division multiplexer - Google Patents
Adjustable optical attenuator and adjustable optical attenuator wavelength division multiplexer Download PDFInfo
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Abstract
The invention provides a kind of adjustable optical attenuator and adjustable optical attenuator wavelength division multiplexer, adjustable optical attenuator comprises strange channel input ports, its by light isolation device to first collimator output beam, also comprise even channel input ports, it is to the first port output beam of the first circulator, second port of the first circulator is to the second collimating apparatus output beam, also comprise birefringece crystal, be positioned at the exit end of first collimator and the second collimating apparatus, the exit end of birefringece crystal is provided with Dispersive Devices, the exit end of Dispersive Devices is provided with condenser lens, Liquid crystal module is arranged on the focal plane of condenser lens, Liquid crystal module has liquid crystal array and catoptron, liquid crystal array has the liquid crystal cells of more than two groups.Adjustable optical attenuator wavelength division multiplexer has dense wave division multiplexer and above-mentioned adjustable optical attenuator.The present invention can realize staggered conjunction ripple, partial wave, and dynamic ground regulates the signal light power of strange channel and even channel, and structure is simple, and production cost is low.
Description
Technical field
The present invention relates to a kind of optical device for optical fiber telecommunications system, specifically, relate to a kind of adjustable optical attenuator and there is the adjustable optical attenuator wavelength division multiplexer of this adjustable optical attenuator.
Background technology
The optical signal transmission speed goes of modern optical fiber telecommunications system is fast, and the capacity of system is also increasing, and this depends on the application of Erbium-Doped Fiber Amplifier (EDFA) (EDFA) and dense wave division multipurpose (DWDM) technology.But, the signal light power unevenness of launching due to optical signal transmitter and the gain spectral unevenness of Erbium-Doped Fiber Amplifier (EDFA), make the light signal of the some different wave lengths in dense wavelength division multiplexing system after Erbium-Doped Fiber Amplifier (EDFA), corresponding gain is inconsistent, and along with the multiple Erbium-Doped Fiber Amplifier (EDFA) cascades uses in long haul communications systems, this gain unevenness is constantly accumulated, cause the power of different channels extremely uneven, cause the dynamic unbalance of optical fiber telecommunications system.
In addition, in fiber optic communication systems, when number of channel increase and decrease or the change of certain channel power of optical transport, also can cause other channel power saltus step, the signal to noise ratio (S/N ratio) of the optical power value that each channel of receiver receives and light signal is also just different.This lack of uniformity is very harmful to the transmission performance of whole optical fiber telecommunications system, often between the signal of Shi Ge road, crosstalk occurs, and makes the bit error rate of some wavelength channel higher than designated value.If unbalanced performance number is too high, light signal transmission generation nonlinear effect in a fiber can be caused, and the optical power value causing receiver to receive exceedes the maximum dynamic range of receiver.If unbalanced performance number is too low, the optical power value that receiver can be caused to receive lower than the sensitivity of receiver, then causes receiver not receive light signal.
Therefore, people's use carries out optical power adjustment to the full tunnel adjustable optical attenuator that the signal light power of each channel carries out dynamic adjustments to the signal of multiple channel, and device the most common is planar waveguide-type variable attenuator array.But, this device only can regulate the luminous power of all channels, can not regulate respectively the luminous power of strange channel or even channel, also dynamically cannot regulate the luminous power of the luminous power of strange channel and even channel, more cannot realize the conjunction light of the signal of strange channel and the signal of even channel.
Also staggered wave multiplexer part is had at present, namely the device closing light is carried out to the signal of strange channel and the signal of even channel, as in Mach-increasing Dare interferometer or the notification number Chinese invention patent application that is CN102262303A the device with polarized composite wave function introduced, these devices have three ports, the signal of a strange channel of port accepts, the signal of an even channel of port accepts, the signal that output port exports is the multiplexed signals comprising the signal of strange channel and the signal of even channel.But this device does not possess the function of the luminous power of the signal of strange channel and the signal of even channel being carried out to dynamic adjustments.
Also exist at present and can carry out dynamic adjustments to the signal light power of multiple channel and the device that can carry out closing to the signal of the signal of strange channel and even channel ripple/point wave energy, as 2 × 1 wavelength-selective switches.Publication number is that the Chinese invention patent application of CN102226848A discloses a kind of wavelength-selective switches, it has collimator array, prism beam expander group, grating, condenser lens and MEMS micro mirror array, MEMS micro mirror array is incided through prism beam expander group, grating, condenser lens successively from the light beam of collimator array outgoing, by the reflection direction regulating the angle of MEMS micro mirror array to change light beam, thus dynamically regulate the luminous power of different channels.But, due to the complex structure of wavelength-selective switches, and cause manufacturing cost high because using MEMS micro mirror array.
Summary of the invention
Fundamental purpose of the present invention is to provide one and has conjunction ripple/point wave energy and the simple staggered adjustable optical attenuator of structure.
Another object of the present invention is to provide the simple and staggered adjustable optical attenuator wavelength division multiplexer that manufacturing cost is lower of a kind of structure.
In order to realize above-mentioned fundamental purpose, adjustable optical attenuator provided by the invention comprises strange channel input ports, its by light isolation device to first collimator output beam, also comprise even channel input ports, it is to the first port output beam of the first circulator, second port of the first circulator is to the second collimating apparatus output beam, adjustable optical attenuator also comprises birefringece crystal, be positioned at the exit end of first collimator and the exit end of the second collimating apparatus, the exit end of birefringece crystal is provided with Dispersive Devices, the exit end of Dispersive Devices is provided with condenser lens, one Liquid crystal module is arranged on the focal plane of condenser lens, Liquid crystal module has and is arranged near the liquid crystal array of condenser lens side and the catoptron away from condenser lens, liquid crystal array has the liquid crystal cells of more than two groups.
From such scheme, after the signal of strange channel and the signal of even channel incide birefringece crystal, grating respectively by two collimating apparatuss, imaging on the focal plane diverse location of condenser lens, the light beam of different channels incides on the different liquid crystal cells of liquid crystal array, by loading different voltage to each liquid crystal cells, change the polarization state through the polarized light of liquid crystal cells, make the rotation of the polarization state generation certain angle of light beam, light polarization after reflection will change, incide the diverse location of birefringece crystal, from different collimating apparatus outgoing.As long as dynamically regulate the magnitude of voltage being loaded into different liquid crystal cells in liquid crystal array, the polarization state anglec of rotation of the light beam of different channels different wave length can be changed, make from the segment beam of strange channel incidence or all light beam from the collimating apparatus outgoing of even channel, realize regulating the signal light power of strange channel, even channel or realize to close light to the signal of strange channel and the signal of even channel.
Further, because adjustable optical attenuator is without the need to arranging expensive and baroque MEMS micro mirror array, and the device architecture used is simple, cheap, make the structure of adjustable optical attenuator simple, and production cost is low.
A preferred scheme is, is provided with birefringece crystal angle of wedge sheet between liquid crystal array and catoptron.Like this, light beam is through after each liquid crystal cells of liquid crystal array, the light beam of different polarization states has different refractive indexes in birefringece crystal angle of wedge sheet, produce different refraction angles, also the different directions of propagation is just had, thus easily by the light beam of different polarization states separately, allow the outgoing from different collimating apparatuss of the light beam of different polarization states.
Further scheme is, light isolation device is the second circulator, and the light beam of the strange channel input ports of the first port accepts of the second circulator, the second port of the second circulator is to first collimator output beam.
As can be seen here, the exit end of strange channel input ports also arranges circulator, by the second circulator, light beam is sent to first collimator, and the 3rd of the second circulator the output port can be utilized to export the signal returned from first collimator, as the output signal of strange channel.
Further scheme is, is provided with at least one piece of unidirectional extended device of light beam between the exit end of birefringece crystal and the incidence end of Dispersive Devices.
Visible, light beam after the unidirectional extended device of light beam from Dispersive Devices outgoing, the hot spot expanded of light beam, be conducive to Dispersive Devices to the more intensive segmentation of incident wave band on it, thus improve diffraction efficiency and resolution, distance between such Dispersive Devices and condenser lens can be done shorter, and the volume of adjustable optical attenuator does less.
In order to realize above-mentioned fundamental purpose, adjustable optical attenuator wavelength division multiplexer provided by the invention comprises strange channel dense wave division multiplexer and/or even channel dense wave division multiplexer, the output terminal of strange channel dense wave division multiplexer and/or even channel dense wave division multiplexer is provided with adjustable optical attenuator, adjustable optical attenuator comprises strange channel input ports, its by light isolation device to first collimator output beam, also comprise even channel input ports, it is to the first port output beam of the first circulator, second port of the first circulator is to the second collimating apparatus output beam, adjustable optical attenuator also comprises birefringece crystal, be positioned at the exit end of first collimator and the exit end of the second collimating apparatus, the exit end of birefringece crystal is provided with Dispersive Devices, the exit end of Dispersive Devices is provided with condenser lens, one Liquid crystal module is arranged on the focal plane of condenser lens, Liquid crystal module has and is arranged near the liquid crystal array of condenser lens side and the catoptron away from condenser lens, liquid crystal array has the liquid crystal cells of more than two groups.
From such scheme, after strange channel dense wave division multiplexer, strange channel input ports is incided from multiple light beams of strange channel incidence, after even channel dense wave division multiplexer, even channel input ports is incided from multiple light beams of even channel incidence, the luminous power of adjustable optical attenuator to the signal of the signal of strange channel and even channel is carried out dynamic adjustments or closes light, thus realizes the adjustable wavelength division multiplex device of staggered luminous power or staggered multiplexer/demultiplexer part.
Further, the structure of adjustable optical attenuator wavelength division multiplexer is simple, and without the need to using the devices such as such as MEMS micro mirror array, production cost is lower.
Accompanying drawing explanation
Fig. 1 is the optical texture schematic diagram of adjustable optical attenuator first embodiment of the present invention.
Fig. 2 is the structure enlarged diagram of the grating of adjustable optical attenuator first embodiment of the present invention, condenser lens and Liquid crystal module.
Fig. 3 is the structure enlarged diagram of the Liquid crystal module of adjustable optical attenuator first embodiment of the present invention.
Fig. 4 is the optical texture schematic diagram of adjustable optical attenuator second embodiment of the present invention.
Fig. 5 is the structure enlarged diagram of the grating of adjustable optical attenuator second embodiment of the present invention, condenser lens and Liquid crystal module.
Fig. 6 is the structure enlarged diagram of the Liquid crystal module of adjustable optical attenuator second embodiment of the present invention.
Fig. 7 is the optical texture schematic diagram of adjustable optical attenuator wavelength division multiplexer first embodiment of the present invention.
Fig. 8 is the optical texture schematic diagram of adjustable optical attenuator wavelength division multiplexer second embodiment of the present invention.
Below in conjunction with drawings and Examples, the invention will be further described.
Embodiment
Adjustable optical attenuator of the present invention regulates for the luminous power of the signal to strange channel and even channel, or the signal realizing strange channel and even channel closes ripple, partial wave, adjustable optical attenuator wavelength division multiplexer is for realizing staggered light splitting, closing light and the luminous power dynamic adjustments to the signal of strange channel and the signal of even channel.
Adjustable optical attenuator first embodiment:
See Fig. 1, the present embodiment has strange channel input ports 11, even channel input ports 12, exports the signal of strange channel and the signal of even channel respectively.The signal propagated in a fiber, after dense wavelength division demodulation multiplexer demultiplexing, is divided into different light beams by according to optical wavelength, and the signal of strange channel and the signal of even channel are the signals of different wave length propagated in fiber optic communication systems.Such as, in the system of 50G hertz channel spacing, the difference on the frequency of two adjacent channels is 50G hertz, channel number in this system is that the channel of odd number is strange channel, the frequency of its channel is the odd-multiple of 50G hertz, in system, channel number is that the channel of even number is even channel, and the frequency of its channel is the even-multiple of 50G hertz, and therefore strange channel and even channel are alternative arrangement.
The signal of multiple strange channel is after strange channel dense wave division multiplexer, can export from an optical fiber, and incide strange channel input ports 11, the signal of multiple even channel is after even channel dense wave division multiplexer, also can export from an optical fiber, incide even channel input ports 12.
The exit end of strange channel input ports 11 is provided with circulator 13, circulator 13 is as a light isolation device, it has three ports, the first port 14 respectively, second port one 5 and the 3rd port one 6, can only from the second port one 5 outgoing from the light of the first port 14 incidence, can only from the 3rd port one 6 outgoing from the light of the second port one 5 incidence, and can not reversely transmit, guaranteeing can not from the first port 14 outgoing from the light of the second port one 5 incidence, avoid light after adjustable optical attenuator, be back to the strange channel dense wave division multiplexer of prime, also just avoid causing crosstalk to backing system.Further, the second port one 5 of circulator 13 is provided with collimating apparatus 17.
After strange channel light beam L11 incides the first port 14 of circulator 13, form light beam L12 from the second port one 5 outgoing, light beam L12 forms light beam L13 after collimating apparatus 17, light beam L13 includes orthogonal two components of polarization state, use arrow to represent the polarization state being parallel to paper direction in Fig. 1, use round dot represents the polarization state perpendicular to paper direction.
The exit end of even channel input ports 12 is also provided with circulator 23, circulator 23 also has three ports, be the first port 24, second port 25, the 3rd port 26 respectively, light can only according to from the first port 24 to the second port 25, transmit from the direction of the second port 25 to the three port 26 in circulator 23.The exit end of the second port 25 is also provided with collimating apparatus 27.
Incide the first port 24 of circulator 23 from the light beam L31 of even channel input ports 12 outgoing after, form light beam L32 from the second port 25 outgoing, light beam L32 forms light beam L33 after collimating apparatus 27, and light beam L33 also includes orthogonal two components of polarization state.
The exit end of collimating apparatus 17,27 is provided with a birefringece crystal 18, and the exit ports of the straight device 17,27 of its plane of incidence positive alignment, can incide the plane of incidence of birefringece crystal 18 from light beam L13, L33 of collimating apparatus 17,27 outgoing.After light beam L13 incides birefringece crystal 18, will form the orthogonal two light beams L14 of polarization state, L15, light beam L14 is ordinary light, and polarization direction is parallel to paper, and light beam L15 is extraordinary ray, and polarization direction is perpendicular to paper.For making the polarization state of the polarized light inciding the rear level system of birefringece crystal 18 identical, the light path of light beam L15 is provided with half-wave plate 19, and half-wave plate 19 is arranged on the exit facet of birefringece crystal 18.Like this, light beam L15 forms light beam L17 after half-wave plate 19, and the polarization direction of light beam L17, compared with the polarization direction of light beam L15, there occurs the deflection of 90 °, its polarization direction is parallel to paper, namely identical through the polarization direction of the light beam L16 after birefringece crystal 18 with light beam L14.
Light beam L33 also forms the orthogonal two light beams L34 of polarization state, L35 after inciding birefringece crystal 18, the polarization direction of light beam L34 is parallel to paper, after birefringece crystal 18 outgoing, form light beam L36, the polarization direction of light beam L36 is identical with the polarization direction of light beam L34.The polarization direction of light beam L35, perpendicular to paper, the light path of light beam L35 is provided with half-wave plate 20, and half-wave plate 20 is positioned on the exit facet of birefringece crystal 18.Light beam L35 forms light beam L37 after half-wave plate 20, and the deflection of 90 ° occurs in polarization direction, and therefore the polarization direction of light beam L37 is identical with the polarization direction of light beam L36.
Be provided with prism beam expander group 30 at the exit end of birefringece crystal 18, it comprises two pieces of prism beam expanders 31,32, and light beam L16, L17, L36, L37 are increased respectively through hot spot after prism beam expander 31,32, and incide in grating 33.The hot spot of the light beam from birefringece crystal 18 outgoing, as the unidirectional extended device of light beam of the present embodiment, expands by prism beam expander 31,32, but the hot spot of light beam incident in the other direction can not be expanded.
Grating 33 is positioned at the exit end of prism beam expander group 30 as Dispersive Devices, light beam L16, L17, L36, L37 form scattering angle difference, wavelength also not identical light beam collection L18, L19, L38, L39 after grating 33, and these four light beam collection form by perpendicular to paper and at the light beam of spatial dispersion.Shown in Fig. 2 is the vertical view of grating 33, condenser lens 34 and Liquid crystal module 36, and light beam L16, after grating 33, will form multiple light beams, and as light beam L181, L182, L183 etc., light beam L181, L182, L183 are the multiple light beams of light beam collection L18.And for example light beam L17 is after grating 33, will form multiple light beams, and as light beam L191, L192, L193 etc., light beam L191, L192, L193 are the multiple light beams of light beam collection L19.
After light beam collection L18, L19, L38, L39 incide the condenser lens 34 being positioned at grating 33 exit end, the direction of propagation changes, and form light beam collection L20, L21, L40, L41 respectively, and the polarization state of light beam collection L20, L21, L40, L41 is identical, is all be parallel to paper.
The exit end of condenser lens 34 is provided with Liquid crystal module 36, as shown in Figure 2 and Figure 3, Liquid crystal module 36 is made up of liquid crystal array 37, birefringece crystal angle of wedge sheet 38 and catoptron 39, liquid crystal array 37 has many group liquid crystal cells 41,42,43 etc., it is positioned at the side near condenser lens 34, and on the focal plane of condenser lens 34, catoptron 39 is positioned at the side away from condenser lens 34, birefringece crystal angle of wedge sheet 38 is between liquid crystal array 37 and catoptron 39.
A large amount of liquid crystal molecule is provided with in each liquid crystal cells, load certain voltage to liquid crystal cells and will change the orientation of liquid crystal molecule, linearly polarized photon is through the liquid crystal cells under different conditions, to there is the rotation of certain angle in polarization state: when loading a specified high voltage to liquid crystal cells, linearly polarized photon is through after liquid crystal cells, polarization state can not deflect, to liquid crystal cells load one be less than specified high-tension voltage after, linearly polarized photon is through after liquid crystal cells, to the deflection of certain angle be there is in its polarization state, the angle of deflection is relevant with the voltage of loading, therefore can be changed the polarization state of the linearly polarized photon through this liquid crystal cells to the voltage on liquid crystal cells by controlled loading.
Because light beam L16, L17, L36, L37 form scattering angle different light beam collection L18, L19, L38, L39 after grating 33, in these light beam collection L18, L19, L38, L39, the light beam of phase co-wavelength incides on the same liquid crystal cells of liquid crystal array 37 after condenser lens 34, but the light beam of the light beam wavelength of concentrating L18, L19, L38, L39 different will incide in the different liquid crystal cells of liquid crystal array 37.Such as, the wavelength of light beam L181 is identical with the wavelength of light beam L191, after condenser lens 34, form light beam L201, L211 respectively, and light beam L201, L211 incide in the same liquid crystal cells of liquid crystal array 37.But the wavelength of light beam L181 is different from the wavelength of light beam L182, and therefore light beam L181, L182 incides in the different liquid crystal cells of liquid crystal array 37 after condenser lens 34.
Because the wavelength of the light beam from strange channel outgoing is not identical with the wavelength of the light beam from even channel outgoing, therefore be focused on the different liquid crystal cells of liquid crystal array 37 from the light beam of strange channel outgoing from the light beam of even channel outgoing, and the light beam of the different wave length be divided into after grating 33 from the light beam of strange channel outgoing is also focused on the different liquid crystal cells of liquid crystal array 37, the light beam of the different wave length be divided into after grating 33 from the light beam of even channel outgoing is also focused on the different liquid crystal cells of liquid crystal array 37.
Different liquid crystal cells to liquid crystal array 37 load different magnitudes of voltage, can change the polarization state of different light beam.Such as, at liquid crystal cells 41, 42 when loading specified high voltage, as 8 volts, light beam L20 is through liquid crystal cells 41, 42 retrodeviate polarization state does not deflect, it is followed refraction law after inciding birefringece crystal angle of wedge sheet 38 and reflects, form light beam L22 and incide on the reflecting surface of catoptron 39, the light beam reflected through catoptron 39 reflects along a reflection paths, form light beam L23, light beam L23 forms light beam L24 also successively through liquid crystal cells 42 after birefringece crystal angle of wedge sheet 38, condenser lens 34, grating 33, prism beam expander group 30, birefringece crystal 18, collimating apparatus 17 incides the second port one 5 of circulator 13, and from the 3rd port one 6 outgoing of circulator 13.
If load lower voltage to liquid crystal cells 41,43, the polarization state of the linearly polarized photon through liquid crystal cells 41,43 can be changed.Such as, liquid crystal cells 41 is loaded lower voltage, light beam L20 is through after liquid crystal cells 42, and the deflection of 90 ° just occurs in polarization direction, therefore through the light polarization of liquid crystal cells 41 perpendicular to paper.This light beam is not followed refraction law after inciding birefringece crystal angle of wedge sheet 38 and is reflected, form deflecting light beams L25 and incide catoptron 39, form folded light beam L26, light beam L26 forms light beam L27 after inciding birefringece crystal angle of wedge sheet 38 and passes liquid crystal cells 43, its polarization state deflects again, travel path is near the lower end of adjustable optical attenuator, therefore light beam L27 will according to this through condenser lens 34, grating 33, prism beam expander group 30, birefringece crystal 18, collimating apparatus 27 incides the second port 25 of circulator 23, from the 3rd port 26 outgoing of circulator 23.
Visible, the different liquid crystal cells of liquid crystal array 37 load different voltage, and from the beam section of strange channel incidence from the 3rd port one 6 outgoing of circulator 13, part is from the 3rd port 26 outgoing of circulator 23.If the 3rd port one 6 of circulator 13 to be set as the exit ports of strange channel signal, 3rd port 26 of circulator 23 is set as the exit ports of even channel signal, like this can from the outgoing of strange channel exit ports from the light beam of strange channel input ports 11 incidence, also can from the outgoing of even channel exit ports, this depends on to the magnitude of voltage loaded without liquid crystal cells in liquid crystal array 37.
Also being incide the different liquid crystal cells of liquid crystal array 37 from the light beam of even channel input ports 12 outgoing, by loading different voltage to different liquid crystal cells, light beam also can being made from the outgoing of strange channel exit ports or from the outgoing of even channel exit ports.
Therefore, if desired adjustable optical attenuator is used to use as staggered wave multiplexer, then in liquid crystal array 37 the liquid crystal cells that passes of the light beam of odd channel do not apply voltage, change the polarization state of the light beam of strange channel outgoing completely, make from the light beam of strange channel outgoing completely from the outgoing of even channel exit ports.Further, the liquid crystal cells that the light beam of all even channels passes in liquid crystal array 37 loads specified high voltage, retrodeviates polarization state and does not deflect, from the outgoing of even channel exit ports from the light beam of even channel outgoing through liquid crystal cells.Because the light beam from strange channel outgoing and the light beam from even channel outgoing are all from the outgoing of even channel exit ports, the signal of the signal and even channel that therefore achieve strange channel closes ripple.
If desired the signal of the strange channel of adjustable optical attenuator dynamic adjustments and the signal light power of even channel is used, the liquid crystal cells that just light beam of the strange channel of part passes in liquid crystal array 37 loads certain voltage, partly change the polarization state of the light beam of strange channel outgoing, make from the light beam of strange channel outgoing a part of from the outgoing of even channel exit ports, another part, from strange channel outgoing, can change the signal light power of strange channel like this.Certainly, when liquid crystal cells quantity is abundant, by changing the quantity of the liquid crystal cells of on-load voltage, can change the signal light power damping capacity of strange channel, the signal of so strange channel and the signal light power ratio of even channel can dynamically regulate.
The signal light power of even channel also dynamically can be regulated by identical method, also by loading different magnitudes of voltage to change the luminous power of the signal from the outgoing of even channel exit ports to the liquid crystal cells of varying number.
During practical application, the signal of even channel exit ports outgoing is used if only need, then circulator 13 can be replaced to a common optoisolator, collimating apparatus 17 can be incided through optoisolator from the light beam of strange channel input ports 11 outgoing, but strange channel input ports 11 can not be incided through optoisolator from the light beam that collimating apparatus 17 returns.
Adjustable optical attenuator second embodiment:
See Fig. 4, the present embodiment has strange channel input ports 51, even channel input ports 52, the exit end of strange channel input ports 51 is provided with circulator 53, first port 54 of circulator 53 receives the light beam L51 from the outgoing of strange channel input ports 51, light beam L51 is from the second port 55 outgoing of circulator 53 and form light beam L52, light beam L52 is incident to collimating apparatus 57, to incide birefringece crystal 58 from the light beam L53 of collimating apparatus 57 outgoing and form the orthogonal two light beams L54 of polarization state, L55, light beam L54 is ordinary light, its polarization state is parallel to paper, light beam L55 is extraordinary ray, its polarization state is perpendicular to paper.
The first port 64 of circulator 63 is incided from the light beam L61 of even channel input ports 52 outgoing, light beam L62 is from the second port 65 outgoing of circulator 63 and incide collimating apparatus 67, the orthogonal two light beams L64 of polarization state, L65 is formed after the light beam L63 of collimating apparatus 67 outgoing incides birefringece crystal 58, wherein the polarization state of light beam L64 is parallel to paper, and the polarization state of light beam L65 is perpendicular to paper.
The exit facet of birefringece crystal 58 is provided with one block of half-wave plate 59, and half-wave plate 59 is positioned in the light path of light beam L55 and light beam L64, for changing the polarization state of light beam L55 and light beam L64.
Light beam L54 forms light beam L56 through after birefringece crystal 58, polarization state can not change, and light beam L55 is through after birefringece crystal 58 and half-wave plate 59, and the deflection of 90 ° occurs polarization state, and form light beam L57, therefore the polarization state of light beam L56 is parallel with the polarization direction of light beam L57.
Light beam L64 forms light beam L66 through after birefringece crystal 58 and half-wave plate 59, and the polarization direction of light beam L66, compared with the polarization direction of light beam L64, there occurs the deflection of 90 °.Light beam L65 is constant through birefringece crystal 58 post deflection direction, and forms light beam L67.Therefore the polarization direction of light beam L66 is parallel with the polarization direction of light beam L67.
Light beam L56, L57 form light beam L58, L59 respectively after inciding the reflecting surface 71 of polarization spectro optics (PBS) 70 and reflex on transparent surface 72, after the transparent surface 72 that light beam L66 incides polarization spectro optics 70 and light beam L58 close light and form light beam L70, therefore light beam L70 includes orthogonal two components of polarization state.Light beam L67 incides after transparent surface 72 and closes light with light beam L59, and formation light beam L71, therefore light beam L71 includes orthogonal two components of polarization state.
Light beam L70, L71 are through being arranged on the prism beam expander group 73 of polarization spectro optics 70 exit end, and prism beam expander group 73 comprises two pieces of prism beam expanders 74,75 as the unidirectional extended device of the present embodiment light beam.Certainly, during practical application, the quantity of used prism beam expander can be determined according to actual service condition.Light beam L70, L71 be spot diameter expanded after prism beam expander group 73, and incides in grating 76 and form light beam collection L72, L73, and each light beam collection L72, L73 all comprise the different multiple light beams of scattering angle.Light beam collection L72, L73 form light beam collection L74, L75 respectively through after condenser lens 77, and incide in Liquid crystal module 78.
Shown in Fig. 5 is the vertical view of grating 76, condenser lens 77 and Liquid crystal module 78, and the light beam collection L72 that light beam L70 is formed after grating 76 comprises scattering angle different and light beam L721, L722, L723 that wavelength is not identical.Light beam L721, L722, L723 form light beam L741, L742, L743 respectively after condenser lens 77, and in the different liquid crystal cells of the liquid crystal array 80 inciding Liquid crystal module 78 respectively.
Certainly, the light beam collection L73 that light beam L71 is formed after grating 76 also comprises the different and light beam that wavelength is different of multi beam scattering angle, and these light beams also incide respectively in the different liquid crystal cells of liquid crystal array 80 after condenser lens 77.Further, light beam collection L72 will incide in the same liquid crystal cells of liquid crystal array 80 with the light beam of phase co-wavelength in light beam collection L73.
See Fig. 6, the Liquid crystal module 78 of the present embodiment is made up of liquid crystal array 80 and catoptron 79, and liquid crystal array 80 comprises many group liquid crystal cells 81,82 etc., and is positioned at the side near condenser lens 77, and catoptron 79 is positioned at the side away from condenser lens 77.
Because the wavelength of the light beam from the outgoing of strange channel input ports 51 is different from the wavelength of the light beam from the outgoing of even channel input ports 52, the light beam that scattering is formed after grating 76 will incide on the different liquid crystal cells of liquid crystal array 80.
By loading different magnitudes of voltage to different liquid crystal cells in liquid crystal array 80, the polarization state of the linearly polarized photon through this liquid crystal cells can be changed.Such as, specified high voltage is loaded to liquid crystal cells 81, light beam L80 can not change through liquid crystal cells 81 rear polarizer direction, the light beam L81 polarization direction formed is parallel to paper, light path again through liquid crystal cells 81 and along incidence after the reflecting surface of catoptron 79 returns, namely after condenser lens 77, grating 76, prism beam expander group 73, polarization spectro optics 70, birefringece crystal 58 and collimating apparatus 57, be incident to the second port 55 of circulator 53 successively, and from the 3rd port 56 outgoing.
If load one to liquid crystal cells 82 to be less than specified high voltage, light beam L82 retrodeviates polarization state through liquid crystal cells 82 and deflects 45 °, the light beam L83 formed returns in liquid crystal cells 82 through the reflecting surface back reflection of catoptron 79, again there is the deflection of 45 ° in the polarization state of light beam, now the polarization state of light beam is perpendicular to paper, this light beam after liquid crystal cells 82 outgoing successively through condenser lens 77, light beam 76, prism beam expander group 73 being incident to the transparent surface 72 of polarization spectro optics 70.The light beam being parallel to paper due to polarization state is reflected onto on reflecting surface 71, and polarization state directly will pass transparent surface 71 perpendicular to the light beam of paper, be incident in birefringece crystal 58.Therefore, the light beam that polarization state changes can not be back in the collimating apparatus of its incidence according to original path, but turns back in another collimating apparatus.Such as, if original light beam L51 from the outgoing of strange channel input ports 51 is through collimating apparatus 57, if the polarization state of this light beam changes, then after reflecting through catoptron 79, by through polarization spectro optics 70 transparent surface 72 and incide in collimating apparatus 67, finally incide the second port 65 of circulator 63, and from the 3rd port 66 outgoing of circulator 63.
Visible, Liquid crystal module 78 by the beam reflection of incidence to condenser lens 77, and by loading different voltage to realize the change of the polarization state to linearly polarized photon to different liquid crystal cells.
If the 3rd port 56 of circulator 53 is set as strange channel exit ports, 3rd port 66 of circulator 63 is set as even channel exit ports, then can from the outgoing of strange channel exit ports from the light beam of strange channel input ports 51 outgoing, also can from the outgoing of even channel exit ports, this depends on the magnitude of voltage to the liquid crystal cells on-load voltage in liquid crystal array 80.In like manner, also can from the outgoing of strange channel exit ports from the light beam of even channel input ports 52 outgoing, or from the outgoing of even channel exit ports.
Like this, if desired adjustable optical attenuator is used as staggered wave multiplexer, then in liquid crystal array, all liquid crystal cells loadings of passing from the light beam of strange channel input ports 51 outgoing are less than specified high voltage, namely change the polarization state of all light beams from the outgoing of strange channel input ports 51, all like this light beams from the outgoing of strange channel input ports 51 will from the outgoing of even channel exit ports.And, in liquid crystal array, all liquid crystal cells passed from the light beam of even channel input ports 52 outgoing load specified high voltage, the polarization state of arbitrary light beam from the outgoing of even channel input ports 52 is not just changed yet, also just bending from the outgoing of even channel exit ports from the light beam of even channel input ports 52 outgoing, realize the conjunction light of the signal of strange channel and the signal of even channel.Further, when being used as staggered wave multiplexer by adjustable optical attenuator, common optoisolator can be used to replace circulator 53.
If desired adjustable optical attenuator is used dynamically to regulate the luminous power of the signal of the signal of strange channel and even channel, then in adjustable liquid crystal display array 80 different liquid crystal cells load different voltage, can make from the beam section of strange channel input ports 51 outgoing from the outgoing of strange channel exit ports, part is from the outgoing of even channel exit ports, and can regulate from strange channel exit ports or from the luminous power of even channel exit ports outgoing, this realizes by regulating the magnitude of voltage of quantity and the loading being loaded the liquid crystal cells of voltage.
Visible, adjustable optical attenuator both can use as staggered wave multiplexer part, also dynamically can regulate the luminous power of the signal of strange channel and even channel, and inapplicable MEMS micro mirror array, structure is simple, and production cost is low.
Adjustable optical attenuator wavelength division multiplexer first embodiment:
See Fig. 7, the present embodiment has strange channel dense wave division multiplexer 91, even channel dense wave division multiplexer 92 and adjustable optical attenuator 97, and adjustable optical attenuator 97 is any one in above-mentioned two adjustable optical attenuator embodiments.
Strange channel dense wave division multiplexer 91 has multiple input port 93, for receiving the signal of multiple strange channel, and being exported from output port 94 by the signal of multiple strange channel conjunction light, exporting in the strange channel input ports 98 in adjustable optical attenuator 97.Even channel dense wave division multiplexer 92 has multiple input port 95, for receiving the signal of multiple even channel, and exporting from output port 96 after the signal of multiple even channel is closed light, exporting in the even channel input ports 99 of adjustable optical attenuator 97.
After the signal of adjustable optical attenuator 97 to the signal of strange channel and even channel carries out the adjustment of closing light or carrying out luminous power, export from output port 100.Like this, adjustable optical attenuator wavelength division multiplexer can carry out conjunction light output to the signal of the signal of strange channel and even channel, uses as staggered wavelength division multiplexer, also can carry out dynamic adjustments to the luminous power of the signal of the signal of strange channel and even channel.
Adjustable optical attenuator wavelength division multiplexer second embodiment:
See Fig. 8, the present embodiment has strange channel dense wave division multiplexer 101 and adjustable optical attenuator 104, strange channel dense wave division multiplexer 101 has multiple input port 102, for receiving the signal of multiple strange channel, and export from output port 103 after the signal of multiple strange channel is closed ripple, export in the strange channel input ports 105 of adjustable optical attenuator 104.After the luminous power of adjustable optical attenuator 104 to the signal of input carries out dynamic adjustments, the signal after process is exported from output port 106.
The even channel input ports 107 of adjustable optical attenuator wavelength division multiplexer 104 is unsettled to be continued to employ, and uses when can expand capacity as subsequent upgrade.Certainly, adjustable optical attenuator wavelength division multiplexer also can be made up of even channel dense wave division multiplexer and adjustable optical attenuator, and the strange channel input ports of adjustable optical attenuator is unsettled to be continued to employ.
Certainly, above-described embodiment is only the preferred embodiment of the invention, also can have more change during practical application, such as, when not considering the volume of adjustable optical attenuator, can not arrange prism beam expander; Or use dispersing prism to substitute grating as Dispersive Devices etc., such change can't affect enforcement of the present invention.
Finally it is emphasized that and the invention is not restricted to above-mentioned embodiment, as the change such as the change of Liquid crystal module formation, the change of light isolation device also should be included in the protection domain of the claims in the present invention.
Claims (8)
1. adjustable optical attenuator, is characterized in that: comprise
Strange channel input ports, described strange channel input ports by light isolation device to first collimator output beam;
Even channel input ports, described even channel input ports is to the first port output beam of the first circulator, and the second port of described first circulator is to the second collimating apparatus output beam;
Birefringece crystal, be positioned at the exit end of described first collimator and the exit end of described second collimating apparatus, the exit end of described birefringece crystal is provided with Dispersive Devices, the exit end of described Dispersive Devices is provided with condenser lens, one Liquid crystal module is arranged on the focal plane of described condenser lens, described Liquid crystal module has and is arranged near the liquid crystal array of described condenser lens side and the catoptron away from described condenser lens, and described liquid crystal array has the liquid crystal cells of more than two groups; Birefringece crystal angle of wedge sheet is provided with between described liquid crystal array and described catoptron.
2. adjustable optical attenuator according to claim 1, is characterized in that:
Described light isolation device is the second circulator, and the light beam of strange channel input ports described in the first port accepts of described second circulator, the second port of described second circulator is to described first collimator output beam.
3. adjustable optical attenuator according to claim 1, is characterized in that:
Described light isolation device is optoisolator.
4. adjustable optical attenuator according to claim 1, is characterized in that:
The exit end of described birefringece crystal is also provided with half-wave plate.
5. adjustable optical attenuator according to claim 4, is characterized in that:
Light path between described half-wave plate and described Dispersive Devices is provided with polarization spectro optics.
6. adjustable optical attenuator according to claim 1, is characterized in that:
At least one piece of unidirectional extended device of light beam is provided with between the exit end of described birefringece crystal and the incidence end of described Dispersive Devices.
7. adjustable optical attenuator wavelength division multiplexer, is characterized in that: comprise
Strange channel dense wave division multiplexer and/or even channel dense wave division multiplexer, the output terminal of described strange channel dense wave division multiplexer and/or even channel dense wave division multiplexer is provided with adjustable optical attenuator, and described adjustable optical attenuator comprises
Strange channel input ports, described strange channel input ports by light isolation device to first collimator output beam;
Even channel input ports, described even channel input ports is to the first port output beam of the first circulator, and the second port of described first circulator is to the second collimating apparatus output beam;
Birefringece crystal, be positioned at the exit end of described first collimator and the exit end of described second collimating apparatus, the exit end of described birefringece crystal is provided with Dispersive Devices, the exit end of described Dispersive Devices is provided with condenser lens, one Liquid crystal module is arranged on the focal plane of described condenser lens, described Liquid crystal module has and is arranged near the liquid crystal array of described condenser lens side and the catoptron away from described condenser lens, and described liquid crystal array has the liquid crystal cells of more than two groups; Birefringece crystal angle of wedge sheet is provided with between described liquid crystal array and described catoptron.
8. adjustable optical attenuator wavelength division multiplexer according to claim 7, is characterized in that:
Described light isolation device is the second circulator, and the light beam of strange channel input ports described in the first port accepts of described second circulator, the second port of described second circulator is to described first collimator output beam.
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| CN103439806A (en) * | 2013-08-06 | 2013-12-11 | 浙江大学 | Reflective thermo-optic variable optical attenuator |
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| CN112737683B (en) * | 2019-10-14 | 2023-05-16 | 华为技术有限公司 | Power equalizer and adjusting method thereof |
| CN113703241B (en) * | 2020-05-21 | 2022-10-18 | 华为技术有限公司 | LCOS adjusting method, optical device and reconfigurable optical add-drop multiplexer |
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| CN102866534A (en) * | 2012-10-08 | 2013-01-09 | 南京大学 | Adjustable optical attenuator |
| US8620131B2 (en) * | 2010-09-30 | 2013-12-31 | INLC Technology, Inc. | Variable optical attenuator (VOA) |
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| US8620131B2 (en) * | 2010-09-30 | 2013-12-31 | INLC Technology, Inc. | Variable optical attenuator (VOA) |
| CN102866534A (en) * | 2012-10-08 | 2013-01-09 | 南京大学 | Adjustable optical attenuator |
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