WO2015054825A1

WO2015054825A1 - Wavelength-division multiplexing (wdm) receiver device and passive optical network system

Info

Publication number: WO2015054825A1
Application number: PCT/CN2013/085221
Authority: WO
Inventors: 王磊; 周小平; 胡菁
Original assignee: 华为技术有限公司
Priority date: 2013-10-15
Filing date: 2013-10-15
Publication date: 2015-04-23
Also published as: CN104969565A; CN104969565B

Abstract

Disclosed are a wavelength-division multiplexing (WDM) receiver device and a passive optical network system. The device comprises: one polarization-dependent array waveguide grating comprising one input waveguide, two FPRs, multiple array waveguides, and a first quantity of output waveguides. The input waveguide receives an incident optical signal having two polarizations, the optical signal is provided with a second quantity of wavelengths, a TE polarized optical signal is chromatically dispersed to a first set of output waveguides via the FPRs and the array waveguides, and a TM polarized optical signal is chromatically dispersed to a second set of output waveguides. Single-mode-multimode couplers are used for receiving a TE polarized optical signal of a corresponding wavelength and outputted by the first set of output waveguides and a TM polarized optical signal of a corresponding wavelength and outputted by the second set of output waveguides and for coupling the TE polarized optical signal and the TM polarized optical signal, both of which are outputted to corresponding photodetectors via a multimode waveguide. The photodetectors convert the coupled optical signals into an electric signal and output same.

Description

A wavelength division multiplexing WDM receiver device and a passive optical network system

Technical field

The present invention relates to the field of communications technologies, and in particular, to a wavelength division multiplexing WDM receiver device and a passive optical network system. Background technique

In a Wavelength Division Multiplex (WDM) optical communication system, signals with multiple optical wavelengths at equal intervals are simultaneously incident on the WDM receiver from the Optical Distribution Network (ODN) and received in the WDM. The machine is spatially separated into different channels by a demultiplexer (DeMutiplexer, Demux), and then received by a photodetector (PD) connected to each channel, and converted into an electrical signal for processing, such as Figure 1 shows. In principle, it is necessary to completely separate the signals of each wavelength to their corresponding channels to avoid interference with other channels.

With the development of optical communication, silicon-on-insulator (SOI)-based silicon light technology has been widely recognized. The S0I-based silicon light platform has the characteristics of small size and low production cost. However, due to the extremely high refractive index difference of the S0I waveguide, the Array Waveguide Grating (AWG) Demux based on the S0I platform encounters severe polarization sensitivity problems. Generally, the light waves transmitted in the optical fiber can be divided into two polarization states, a transverse electric mode TE and a transverse magnetic mode TM. The S0I-based AWG has different refractive indices for the two polarizations, and therefore the same polarization state, the same The wavelength of the optical signal is dissipated to two different locations, making the device unable to perform the demultiplexing function.

For the polarization-insensitive De leg X on the SOI, various solutions have been proposed, such as polarization separation of incident light by a grating coupler, and then demultiplexing by two AWGs respectively, and then using multiple The grating coupler combines the light waves of the same wavelength channel. In principle, this structure can solve the polarization-sensitive problem, but this design requires a complex polarization separation grating auxiliary coupler, which requires high fabrication precision. In addition, two AWGs are needed, which increases the area of the entire device. The two AWGs can be realized by completely aligning the demultiplexing wavelengths of the channel to the channel, so it is very difficult to implement. Summary of the invention

Embodiments of the present invention provide a wavelength division multiplexing WDM receiver device and a passive optical network system, which have the characteristics of low cost, designization, and high process tolerance.

In a first aspect, an embodiment of the present invention provides a wavelength division multiplexing WDM receiver device, including: a polarization dependent arrayed waveguide grating, including an input waveguide, and two free diffraction regions

An FPR, a plurality of arrayed waveguides and a first number of output waveguides; said input waveguide receiving incident two wavelength-division-wavelength multiplexed WDM optical signals having transverse electrical mode TE polarization and transverse magnetic mode TM polarization, said WDM light The signal has a second number of wavelengths and disperses the TE-polarized optical signal to the first set of output waveguides by the plurality of arrayed waveguides between the two FRPs and the two FRPs, The optical signal is dispersed to a second set of output waveguides; wherein the first number is twice the second number; a plurality of single mode-multimode couplers, each of the single mode multimode couplers for receiving the a set of TE-polarized light signals of a corresponding wavelength outputted from the output waveguide, and a TM-polarized light signal of a corresponding wavelength outputted by the second set of output waveguides, and coupling the TE-polarized light signal and the TM-polarized light signal, and outputting through the multimode waveguide ;

a plurality of photodetectors, each of the photodetectors receiving a coupled TE polarized light signal and a TM polarized light signal corresponding to the multimode waveguide output, and polarizing the coupled TE polarized light signal and TM The optical signal is converted into an electrical signal output.

In a first possible implementation manner, the optical signal of the TE polarization is dispersed to the first group of output waveguides by the plurality of array waveguides between the two FRPs and the two FRPs, and the TM polarization is performed. The dispersion of the optical signal to the second set of output waveguides is specifically:

The WDM optical signal passes through the corresponding array waveguide according to different powers after passing through the first FRP After transmission, incident on the second FPR, the optical signal polarized by the transverse mode TE is dispersed to the first set of output waveguides by the second FPR, and the optical signal polarized by the transverse mode TM is dispersed to the output of the second set of output waveguides. Wherein the adjacent two arrayed waveguides have a fixed length difference therebetween.

In a second possible implementation manner, the wavelength of the WDM optical signal and the output angle β _ΤΕ of the TE-polarized optical signal after dispersion satisfy:

n _TE ds in β + n _ΤΕ Δ =ηι _ΤΕ λ

Where n _TE and n' _TE are the refractive indices of the FPR and the array waveguide under TE polarization, respectively; m _TE is the diffraction order of the TE polarization; d is the spacing of the adjacent two array waveguides at the FPR entrance; λ is the WDM light The wavelength of the signal; is the difference in length between two adjacent arrayed waveguides.

With reference to the first aspect or the second implementation manner of the first aspect, in a third possible implementation manner, the first group of output waveguides is a first quantity, and the first group of output waveguides includes a first quantity The diffraction order of the ΤΕ output waveguide is the same.

In a fourth possible implementation manner, the wavelength of the WDM optical signal and the output angle βTM of the dispersed ΤΜ-polarized optical signal satisfy:

n _TM ds in β τΜ + η' _ΤΜ Δ = ηι _ΤΜ λ

Where η _ΤΜ and η′ _ΤΜ are the refractive indices of the FPR and the array waveguide under TE polarization, respectively; m _TM is the TM polarization diffraction order; d is the spacing of the adjacent two array waveguides at the FPR inlet; λ is the WDM optical signal Wavelength; is the difference in length between adjacent two arrayed waveguides.

With reference to the first aspect or the fourth implementation manner of the first aspect, in a fifth possible implementation manner, the second group of output waveguides is a first quantity, and the second group of output waveguides includes a first quantity The diffraction order of the ΤΜ output waveguide is the same.

In a sixth possible implementation, the diffraction order corresponding to the first set of output waveguides is different from the diffraction order corresponding to the second set of output waveguides.

In a seventh possible implementation, the number of the single mode multimode coupler, the multimode waveguide, and the photodetector is specifically the first number.

In an eighth possible implementation, the location of the first set of output waveguides and the second group The positions of the output waveguides do not overlap.

In a second aspect, an embodiment of the present invention provides a passive optical network system, where the passive optical network system includes the wavelength division multiplexing WDM receiver device provided by the first aspect.

The wavelength division multiplexing WDM receiver device of the embodiment of the present invention adopts an AWG to separate wavelength and polarization, and adopts a single mode-multimode coupling structure at the same time, has low cost, design tubular characteristics and high process tolerance capability. . DRAWINGS

1 is a schematic diagram of a wavelength division multiplexing receiver device in the prior art;

2 is a schematic diagram of a WDM receiver device according to an embodiment of the present invention; FIG. 3 is a schematic structural diagram of an AWG according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a passive optical network system according to an embodiment of the present invention.

The technical solutions of the embodiments of the present invention are further described in detail below with reference to the accompanying drawings and embodiments. detailed description

The wavelength division multiplexing WDM receiver device provided by the embodiment of the invention can be applied to a silicon optical communication system, and is particularly suitable for solving the polarization sensitivity problem of a WDM receiver having an AWG Demux based on the S0 I basis.

FIG. 2 is a schematic diagram of a WDM receiver apparatus according to an embodiment of the present invention. As shown, the WDM receiver device includes: a polarization dependent AWG 1, a plurality of single mode multimode couplers 2, and a plurality of photodetectors 3.

A polarization dependent AWG 1 comprising an input waveguide 1 1 , two FPR 1 21, 122, m array waveguides 1 23 and 2n output waveguides 1 3 , where m and n are positive integers. The input waveguide 13 receives the incident WDM optical signal having two polarizations, TE polarization and TM polarization, respectively. The WDM optical signal has n wavelengths, and the optical signal polarized by the transverse mode TE is dispersed by the FRP 12 to The first set of output waveguides 1 31 scatters the transverse magnetic mode ΤΜ polarized optical signal to the second set of output waveguides 1 32. The structure of the AWG is specifically shown in the schematic diagram of the AWG structure of FIG. In AWG 1, the two FPRs 121 and 122 are identical in structure, and are preferably composed of arcs of tangent circles with two radii of two times on the upper and lower boundaries. The small circle is called the Roland circle, and the large circle is called the grating. The circle, the inlet and the outlet of the arrayed waveguide 123 are respectively arranged on the grating circle, and the entrances of the input waveguide 11 and the output waveguide 13 to the FPRs 121 and 122 are sequentially arranged on the Roland circle.

The WDM optical signal is input from the input waveguide 11. After the first FPR 121, the light wave diverges into the m array waveguide 123 for transmission according to different powers. In the array waveguide 123, the length difference between the adjacent two array waveguides is a fixed value. The light waves are transmitted through the arrayed waveguide 123 and then incident on the second FPR 122. Due to the interference of the arrayed waveguides 123, light waves of different wavelengths enter different positions of the second FPR 122 and are received by the corresponding output waveguides 13. And because for the light waves of TE polarization and TM polarization, the array waveguide 123 and the FPRs 121, 122 have different refractive indices for the two polarized light waves, so the light waves of the same wavelength for the TE polarization and the TM polarization also enter. The second FPR 122 has a different location.

The wavelengths of the WDM optical signal and the output angles of the TE polarized and TM polarized optical signals β _ΤΕ and _βTM respectively satisfy:

n _TE ds ΐηβχΕ + η _ΤΕ Δ = ηι _ΤΕ λ (Formula 1) n _TM ds in _TM + η' _ΤΜ Δ = ηι _ΤΜ λ

Where η _ΤΜ and η′ _ΤΜ are the refractive indices of the FPR and the array waveguide under TE polarization, respectively; n _TM and n′ _TM are the refractive indices of the FPR and the array waveguide under TE polarization, respectively; 13⁄4 is the diffraction order of the TE polarization; m _TM is the diffraction order of TM polarization; d is the spacing of adjacent two array waveguides at the FPR entrance; λ is the wavelength of the WDM optical signal; is the difference in length between two adjacent arrayed waveguides. The β _ΤΕ or _βTM is specifically the angle between the center line of the ΤΕ or ΤΜ waveguide outputted in the second FPR and the line connecting the grating circle and the Roland circle puncturing point to the center of the grating circle.

It can be seen that the AWG can disperse optical signals of different wavelengths and different polarization states to corresponding positions of the FPR. In this embodiment, the ΤΕpolarized light signal is dissipated to the top shown in Figure 2. n adjacent output waveguides, i.e., the first set of output waveguides 1 31; the TM polarized optical signals are dispersed to the lower n adjacent output waveguides shown in Figure 2, i.e., the second set of output waveguides 1 32.

The relative position between the first set of output waveguides 1 31 and the second set of output waveguides 1 32 is determined by the diffraction orders m _TE and m _TM utilized by TE, TM polarization. They can be the same or not the same. When the waveguide has a large difference in refractive index between the two polarizations, if the TE and TM polarizations use the same diffraction order, the position of the TM output waveguide will deviate from the TE group [艮远. Typically, the AWG is characterized by a centrally located output waveguide that achieves maximum coupling efficiency, and the lower the edge, the coupling efficiency is lower, so all output waveguides are placed as close as possible so that the energy received by each waveguide is as uniform as possible.

Multiple single mode - multimode couplers 2. Each single mode-multimode coupler 2 is configured to receive a 波长 polarized light signal of a corresponding wavelength output of a first set of output waveguides of one wavelength and a ΤΜ polarized light signal of a corresponding wavelength output by the second set of output waveguides, and The polarized light signal is coupled to the ΤΜpolarized light signal and output through a multimode waveguide (not shown). Therefore, for a WDM optical signal having η wavelengths, there are also η single-mode multimode couplers 2 for receiving and coupling n sets of ΤΕ-polarized light signals and ΤΜ-polarized light signals of different wavelengths.

a plurality of photodetectors 3 each receiving a coupled ΤΕ-polarized light signal and a ΤΜ-polarized light signal output by a multimode waveguide (not shown) of the corresponding single-mode multimode coupler 2, The coupled ΤΕpolarized light signal and the ΤΜpolarized light signal are converted into an electrical signal output. Correspondingly, the number of photodetectors 3 is also n.

The various components constituting the WDM receiver device have been described in detail above, and the operation of the WDM receiver device composed of the above-described respective components will be described below in conjunction with the schematic diagram of the WDM receiver device shown in FIG.

The WDM signal with n polarizations of two polarizations transmitted by the optical distribution network is incident on the incident waveguide of a polarization-dependent AWG. Due to the polarization dependence of the AWG, the ΤΕpolarized WDM signal is dispersed to the above n adjacent The waveguide 1 31 is output, and the chirp signal is dispersed to the lower n adjacent output waveguides 1 32 and output in a single mode. Then, the two output waveguides 1 31 and 1 32 corresponding to each wavelength are coupled to the same multimode waveguide through a single mode-multimode coupler 2 (in the figure) Not shown) inside. Since the multimode waveguide has more modes, the energy of the two output single mode waveguides can theoretically be losslessly coupled to the corresponding photodetector 3 through a multimode waveguide (not shown). Therefore, the function of the polarization insensitive WDM receiver can be realized.

The WDM receiver provided by the embodiment of the present invention reduces the cost and the polarization by using an AWG to separate the wavelength and polarization of optical signals of multiple wavelengths having two polarizations without using an additional polarization separator or other AWG. The area of the entire device; By using a single-mode-multi-mode coupling structure, a complex polarization multiplex structure is avoided, and the single-mode multi-mode coupling structure has a higher process tolerance than the polarization multiplex structure. Easy to implement; In addition, by using different diffraction orders for TE and TM, the overall coupling efficiency can be improved.

The embodiment of the present invention further provides a passive optical network system, which may be a wavelength division multiplexed passive optical network (WDM P0N) system as shown in FIG. The WDM P0 system 400 includes an optical line terminal 410 located at a central office (CO) and a plurality of optical network units 420 located at the user side, wherein the optical line terminal 410 passes through an optical distribution network (Optical Distribution Network, 0DN) ) 430 is connected to the plurality of optical network units 420. The optical distribution network 430 may include a backbone optical fiber 431, a wavelength division multiplexing/demultiplexing 432, and a plurality of branching fibers 433, wherein the trunk optical fiber 431 is connected to the optical line terminal 410 and passes the wavelength division A multiplexer/demultiplexer 432 is connected to the plurality of branch fibers 433, which are respectively connected to the optical network unit 420. The wavelength division multiplexing/demultiplexing device 432 may be a remote node (RN), an Array Waveguide Grating (AWG), that is, a remote AWG (RN-AWG). ) 432.

The optical line terminal 410 includes a plurality of central office transceiver modules 411, and the plurality of OLT transceiver modules 411 pass through another wavelength division multiplexing/demultiplexing device 412 located at the central office, such as a central office AWG (C0-AWG). Coupled to the backbone fiber 431. Each optical network unit 420 includes a client transceiver module 421. The client transceiver module 421 and the office transceiver module 411 have a one-to-one correspondence, and each pair of the office transceiver module 411 and the client transceiver module 421 respectively use different communication wavelengths (λ1, λ2, ... Λη) performs similar point-to-point communication. The central office transceiver module of the figure 411 includes a laser, a wavelength division multiplexer WDM and a receiver, and the receiver is a WDM receiver device described in the embodiment corresponding to FIG. 2 and FIG. 2 of the embodiment of the present invention. As shown in FIG. 2, the WDM receiver device includes: a polarization dependent AWG 1, a plurality of single mode-multimode couplers 2, and a plurality of photodetectors 3. For details, please refer to FIG. 2 and the description of the corresponding embodiments. The specific structure of the WDM receiver device will not be described here.

The above described embodiments of the present invention are further described in detail, and the embodiments of the present invention are intended to be illustrative only. The scope of the protection, any modifications, equivalents, improvements, etc., made within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

claims

1. A wavelength division multiplexing WDM receiver device, characterized in that the device includes: a polarization-dependent arrayed waveguide grating, including an input waveguide, two free diffraction regions FPR, a plurality of arrayed waveguides and a first number The output waveguide; the input waveguide receives the incident wavelength division multiplexed WDM optical signal with two polarizations of transverse electric mode TE polarization and transverse magnetic mode TM polarization, the WDM optical signal has a second number of wavelengths, and passes The two FRPs and the plurality of array waveguides between the two FRPs disperse the TE-polarized optical signals to a first group of output waveguides, and disperse the TM-polarized optical signals to a second group of output waveguides; wherein said first quantity is twice the second quantity;

A plurality of single-mode to multi-mode couplers, each of the single-mode and multi-mode couplers is used to receive TE polarized light signals of corresponding wavelengths output by the first group of output waveguides, and corresponding wavelengths output by the second group of output waveguides. TM polarized light signal, coupling the TE polarized light signal and the TM polarized light signal, and outputting them through a multi-mode waveguide;

A plurality of photodetectors, each of which receives the coupled TE polarized light signal and TM polarized light signal output from the corresponding multi-mode waveguide, and polarizes the coupled TE polarized light signal and TM polarized light signal. The optical signal is converted into an electrical signal for output.

2. The device according to claim 1, wherein the TE polarized optical signal is dispersed to a first group of outputs through the two FRPs and a plurality of array waveguides between the two FRPs. The waveguide, which disperses the TM polarized optical signal to the second set of output waveguides, is specifically:

After passing through the first FRP, the WDM optical signal is transmitted through corresponding array waveguides according to different powers and then is incident on the second FPR. The transverse electric mode TE polarized optical signal is dispersed to the first group of outputs through the second FPR. The waveguide disperses the optical signal polarized in the transverse magnetic mode TM to the second group of output waveguides for output; wherein, there is a fixed length difference between two adjacent array waveguides.

3. The device according to claim 1, wherein the wavelength of the WDM optical signal and the output angle β _TE of the TE polarized optical signal after dispersion satisfy:

n _TE d sinp _TE + η _ΤΕ Δ L=m _TE in

Among them, n _TE and n' _TE are the refractive index of FPR and array waveguide under TE polarization respectively; m _TE is TE polarization. is the diffraction order of the vibration; d is the spacing between two adjacent array waveguides at the FPR entrance; λ is the wavelength of the WDM optical signal; AL is the length difference between two adjacent array waveguides.

4. The device according to claim 3, wherein the first group of output waveguides is a first number, and the diffraction orders corresponding to the first number of TE output waveguides included in the first group of output waveguides are the same. .

5. The device according to claim 1, characterized in that the wavelength of the WDM optical signal and the output angle β _TM of the dispersed TM polarized optical signal satisfy:

n _TM d sinPiM + η' _ΤΜ ^Δ L=m _TM in

Among them, n _TM and n' _TM are the refractive index of FPR and array waveguide under ΤE polarization respectively; m _TM is the TM polarization diffraction order; d is the spacing between two adjacent array waveguides at the FPR entrance; λ is the WDM optical signal wavelength; Δ |_ is the length difference between two adjacent array waveguides.

6. The device according to claim 5, wherein the second group of output waveguides is a first number, and the diffraction orders corresponding to the first number of TM output waveguides included in the second group of output waveguides are the same. .

7. The device according to claim 1, wherein the diffraction orders corresponding to the first group of output waveguides are different from the diffraction orders corresponding to the second group of output waveguides.

8. The device according to claim 1, wherein the number of single-mode-multimode couplers, multi-mode waveguides and photodetectors is specifically a first number.

9. The device according to claim 1, wherein the positions of the first group of output waveguides and the positions of the second group of output waveguides do not overlap.

10. A passive optical network system, characterized in that the passive optical network system includes the wavelength division multiplexing WDM receiver device as claimed in claim 1.