Be used for fiber-to-the-home planar type optical waveguide single-fiber three-way multiplexer
Technical field
The invention belongs to Optical Access Network network field, in particular for the single-fiber three-way multiplexer that Fiber to the home (FTTH), particularly a kind of single-fiber three-way multiplexer based on plane integrated optics technique (PLC, PlanarLightwave Circuit).
Technical background
Considerable progress along with Optical Access Network network technology, and the increase of traffic carrying capacitys such as IPTV, video request program and online game, the user further increases the demand of access bandwidth, require more and more higher to the Optical Access Network network, FTTH has become the main technical schemes of Optical Access Network network, and EPON (PON) technology is the mainstream technology of FTTH, and it can realize video, voice, data unification of three nets.Be used for the PON technology of FTTH, realize that the core devices of communicating by letter between optical line terminal (OLT) and the terminal use is exactly a single-fiber three-way multiplexer, develop that to satisfy communication bandwidth requirement, low cost, low-loss single-fiber three-way multiplexer be the actual demand of application, therefore have very important significance.These actual requirements also are the key factors of restriction FTTH technology popularization.
The major function of single-fiber three-way multiplexer, be with the voice signal of the wavelength 1490nm of OLT output and the vision signal of wavelength 1550nm, and the wavelength 1310nm signal multiplexing that the user uploads advances an optical fiber, and the user can receive 1490nm voice signal and wavelength 1550nm vision signal respectively by receiver.The single-fiber three-way multiplexer of practical application at present is based on the discrete device technology, has the encapsulation of being not easy to, coupling loss is big and shortcoming such as cost height; And utilize the single-fiber three-way multiplexer of integrated optics technique, and focus mostly at present in based on multimode waveguide coupler (MMI) with based on array waveguide grating (AWG) two big classes, it is low to have coupling loss, compact conformation and be easy to extensive integrated advantage.Wherein MMI has again that polarization loss is low, processing advantages such as tolerance is big, but owing to utilize traditionally from imaging phenomenon and wavelength division multiplexing principle design, the length of device is very long, compact inadequately.With the immediate prior art of the present invention is to adopt the single-fiber three-way multiplexer of the MMI formation of two cascades, referring to accompanying drawing 1, and adopt based on extra down length (the Jong-Kyun Hong that reduces device from the imaging phenomenon of weak sliver spare, Sang-Sun Lee, PLC-based novel triplexer with a simple structure foroptical transceiver module application, IEEE Photonics TechnologyLetters, vol.26, No.1, pp21-23,2008), yet in this structure, the output arm of MMI, straight-through arm of input and input coupling arm are the waveguide of band bending section, and the length of curved waveguide is big, the processing cost height causes device size big, the shortcoming that loss is high, and do not consider bandwidth requirement.In addition, the inside and outside researcher's single-fiber three-way multiplexer spare acp chip structure Design of paying close attention to of present stage host country also do not relate to for the monitoring of the input optical fibre operating state in the single-fiber three-way multiplexer more.
Summary of the invention
For the device size that overcomes prior art is big, the shortcoming that loss is high, it is little to the invention provides a kind of device size, and loss is used for fiber-to-the-home planar type optical waveguide single-fiber three-way multiplexer for a short time.
Be used for fiber-to-the-home planar type optical waveguide single-fiber three-way multiplexer, comprise the input optical fibre of importing first light signal, launch first transmitter of second light signal and second transmitter of emission the 3rd light signal, described input optical fibre is connected by the output arm of beam splitter with a multimode waveguide coupler; The straight-through arm of the input of described multimode waveguide coupler is sent to receiver with first light signal; Described first transmitter is connected with the input coupling arm of described multimode waveguide coupler, and described second transmitter is connected with described multimode waveguide coupler by curved waveguide, the described output arm output of described second, third optical signals; Described curved waveguide comprise bending section with the parallel straightway of described input coupling arm;
It is characterized in that: described input coupling arm is a straight wave guide, described input coupling arm and described straightway form the parallel waveguide coupling regime, described input coupling arm and described bending section form straight wave guide-curved waveguide coupling regime, and described straight wave guide-curved waveguide coupling regime adopts described second, third light signal of finite difference beam propagation method coupling.
Described first light signal is that wavelength is the light wave of 1310nm, and second light signal is that wavelength is the light wave of 1550nm, and the 3rd light signal is that wavelength is the light wave of 1490nm.
Further, when described single-fiber three-way multiplexer also is provided with and can obtains each light signal respectively and in the luminous power of the luminous power of input and output and with each light signal input optical power is being arranged, corresponding Output optical power is arranged is the monitoring module of normal operating conditions, the output of described beam splitter is connected with the input of described monitoring module, and the output of the input of described receiver, first transmitter, the output of second transmitter are connected with the input of described monitoring module respectively.
Further, described curved waveguide adopts the buried glass based waveguides.The sandwich layer refractive index of described waveguide is n
c=1.4603, cladding index n
s=1.4582, the single mode waveguide cross section of input and output is 6 μ m * 6 μ m.
Further, the length of described parallel waveguide coupling regime is 8822 μ m, and the spacing of described input coupling arm and described straightway is 1.2 μ m; The length of described straight wave guide-curved waveguide coupling regime is 3200 μ m.
Further, the width of described multimode waveguide coupler is 18 μ m, and length is 3870 μ m.
The invention has the beneficial effects as follows: 1, the input coupling arm of multimode waveguide coupler adopts straight wave guide, and with respect to traditional curved waveguide, its length is lacked, makes component compact, reduced the loss of light signal, and processes simply, and cost is low.2, the monitoring module that adds single-fiber three-way multiplexer is monitored the connection status between the optical fiber and waveguide in working optical fibre between OLT and the user and the single-fiber three-way multiplexer in real time, ensures the unobstructed of communication.3, the coupling loss between glass medium fiber waveguide and the optical fiber is low.
Description of drawings
Fig. 1 is a prior art single-fiber three-way multiplexer structural representation
To be that the present invention is a kind of be used for fiber-to-the-home novel planar optical-waveguide-type single-fiber three-way multiplexer structural representation to Fig. 2
Beam Propagation curve chart when Fig. 3 (a) is MMI input 1310nm operation wavelength
Beam Propagation curve chart when Fig. 3 (b) is MMI input 1490nm operation wavelength
Beam Propagation curve chart when Fig. 3 (c) is MMI input 1550nm operation wavelength
Beam Propagation curve chart when Fig. 4 (a) is curved waveguide input 1490nm wavelength
Beam Propagation curve chart when Fig. 4 (b) is curved waveguide input 1550nm wavelength
Fig. 5 is that the present invention scans the simulation output spectra that obtains when wave-length coverage is 1000nm to 1800nm
Embodiment
With reference to accompanying drawing, further specify the present invention:
Be used for fiber-to-the-home planar type optical waveguide single-fiber three-way multiplexer, comprise the input optical fibre 1 of importing first light signal, launch first transmitter 2 of second light signal and second transmitter 3 of emission the 3rd light signal, described input optical fibre 1 is connected with the output arm 51 of a multimode waveguide coupler 5 by beam splitter 4; The straight-through arm 52 of the input of described multimode waveguide coupler 5 is sent to receiver 6 with first light signal; Described first transmitter 2 is connected with the input coupling arm 53 of described multimode waveguide coupler 5, described second transmitter 3 is connected with described multimode waveguide coupler 5 by curved waveguide 7, described output arm 51 outputs of described second, third optical signals; Described curved waveguide 7 comprises bending section 71 and the straightway 72 parallel with described input coupling arm 53;
Described input coupling arm 53 is a straight wave guide, described input coupling arm 53 forms the parallel waveguide coupling regime with described straightway 72, described input coupling arm 53 forms straight wave guide-curved waveguide coupling regime with described bending section 71, and described straight wave guide-curved waveguide coupling regime adopts described second, third light signal of finite difference beam propagation method coupling.Described first light signal is that wavelength is the light wave of 1310nm, and second light signal is that wavelength is the light wave of 1550nm, and the 3rd light signal is that wavelength is the light wave of 1490nm.
The 3rd light signal is through entering input coupling arm 53 after straight wave guide-the curved waveguide coupling regime is multiplexing, utilize additionally second light signal (1550nm light wave) and the 3rd light signal (1490nm light wave) being closed the ripple signal and being coupled into output arm 51 of multimode waveguide coupler under the weak sliver spare, will close the ripple signal by input optical fibre and export from the imaging principle.
Additionally being meant of multimode waveguide coupler: under weak sliver spare from the imaging principle, because the Gu Hanxin displacement causes the phase mismatch of guided mode in the multimode zone of multimode waveguide coupler, what the multimode waveguide coupler formed additionally is observed from imaging is easier, and increase along with multimode waveguide coupler device length, this extra better than multimode waveguide coupler tradition from imaging from the quality of imaging, therefore can utilize the multimode waveguide coupler waveguide coupler that additionally has the wavelength division multiplexing function from the imaging design.
When described single-fiber three-way multiplexer also is provided with and can obtains each light signal respectively and in the luminous power of the luminous power of input and output and with each light signal input optical power is being arranged, corresponding Output optical power is arranged is the monitoring module 8 of normal operating conditions, the output of described beam splitter 4 is connected with the input of described monitoring module 8, and the output of the input of described receiver 6, first transmitter 2, the output of second transmitter 3 are connected with the input of described monitoring module 8 respectively.
Described curved waveguide 7 adopts the buried glass based waveguides.The sandwich layer refractive index of described waveguide is n
c=1.4603, cladding index n
s=1.4582, the single mode waveguide cross section of input and output is 6 μ m * 6 μ m.
The length of described parallel waveguide coupling regime is 8822 μ m, and the spacing of described input coupling arm and described straightway is 1.2 μ m; The length of described straight wave guide-curved waveguide coupling regime is 3200 μ m.
The width of described multimode waveguide coupler 5 is 18 μ m, and length is 3870 μ m.
Referring to accompanying drawing 5, the output spectra of analogue device can find that the three dB bandwidth of 1310nm, 1490nm and 1550nm wavelength is respectively 160nm, 34nm and 45nm, satisfies 100nm, the 20nm of ITU regulation and the communicating requirement of 20nm.Isolation is 14.6dB between 1490nm and the 1550nm, isolation optimal value between 1310nm wavelength and 1490nm, the 1550nm is respectively 21.6dB and 23.2dB, and during actual transmissions since the transmitted in both directions of upward signal and downstream signal every degree can reach fully the ITU regulation greater than the 45dB requirement, because 1310 wavelength are that the echo reflection of end face during by optical fiber and waveguide-coupled produces to crosstalking of other two ports, can be by improving the coupling encapsulation increase return loss of optical fiber and waveguide chip.The coupling loss of operation wavelength 1310nm, 1490nm and 1550nm (comprising and optical fiber coupling loss) is respectively 1.5dB, 0.5dB and 1.3dB.
The described content of this specification embodiment only is enumerating the way of realization of inventive concept; protection scope of the present invention should not be regarded as only limiting to the concrete form that embodiment states, protection scope of the present invention also reach in those skilled in the art conceive according to the present invention the equivalent technologies means that can expect.