KR101096189B1 - Method for implementing the super-low price effective WDN-PON - Google Patents

Abstract

The present invention relates to a method for implementing an ultra-low-cost wavelength division multiplexing passive optical subscriber network, using a plurality of low-cost Fabry-Perot laser diodes (FP LD ₁ to FP LD _N ) as a light source of a transmitter, and using the Fabry-Perot laser. The optical signal from the diodes FP LD ₁ to FP LD _N is multiplexed with an NxN wavelength division multiplexer (NxN AWG1), and the N-1 output beams are mixed with N-1x1 optocouplers. By applying to the Fabry-Perot laser diode (FP LD) transmitter through the oscillator, the multiplexed signal is demultiplexed through a 1xN wavelength division demultiplexer (1xN AWG) and received by multiple PIN photodetectors (PD1 to PDN). Ultra-low cost implementation, N-1 channel beams in NxN AWG minus one channel for optical signal transmission are non-coherent for injection locking of Fabry-Perot laser diodes (FP LD) Used as beams, these beams are insensitive to temperature changes by combining N-1 beams through an Nx1 optocoupler to create an incoherent beam, which eliminates the need for additional control circuitry for temperature compensation. It is a useful invention with the particular advantage that a WDM-PON configuration is possible but in particular does not require an incoherent external injection beam.

Description

Method for implementing the super-low price effective WDN-PON}

The present invention relates to a wavelength division multiplex passive optical subscriber network implementation method, and more particularly, to a wavelength division multiplex passive optical subscriber network (hereinafter referred to as "WDM-PON"). The present invention relates to an ultra low-cost wavelength division multiplex passive optical subscriber network.

As the use of the Internet increases and the generalization of video and video-oriented services, subscriber demand for high-speed services is increasing rapidly. To satisfy this, the speed-up method should be easy and economical to accommodate many subscribers.

The most representative method of the conventional WDM-PON implementation method is using a distributed feedback laser diode (hereinafter referred to as "DFB-LD"). The generated light is fixed to a specific wavelength, and then waveguide array The most common method is to construct an optical subscriber network through multiple and demultiplex processes through an arrayed waveguide grading (AWG).

The disadvantage of this method is that the value of the DFB-LD is still expensive, and the DFB-LD having a wavelength suitable for the AWG channel must be prepared. Thus, the proposed method injects an incoherent beam into a low-cost Fabry-perot Laser Diode (FP LD), which can be laser-injected into a single mode, similar to DFB-LD. A laser diode light source (domestic patent 0059923) has been proposed.

This method has the advantage of using a low-cost Fabry-Perot laser diode (F-P LD) and does not have to be equipped with a laser diode (LD) having a specific wavelength for each AWG channel (colorless). However, inducing injection locking of each Fabry-Perot laser diode (F-P LD) requires the provision of an incoherent injection beam, which usually uses a wideband EDFA, resulting in a price increase.

That is, the conventional representative implementation method of the WDM-PON is configured based on the DFB-LD light source. The DFB-LD is a single-mode oscillation laser and is an essential light source device commonly used for medium and long distance optical communication using wavelength division multiplexing (WDM).

However, although DFB-LD can generate laser light with a single mode wavelength, there is a wavelength change of about 0.1 nm / ° C depending on the temperature, and thus a device capable of stabilizing the wavelength is required. Accordingly, a laser diode (Laser Diode, Hereinafter, packaging of "LD" also has the disadvantage of using an expensive butterfly (butterfly) form.

Therefore, when the WDM-PON is configured using the DFB-LD, the light source itself is expensive, and the system implementation cost is increased due to the device for stabilizing the wavelength and the devices for controlling the WDM-PON.

In order to solve this problem, Patent Nos. 0325687 and 0473520 proposed that a pseudo single mode light source can be made by injecting an incoherent light source into a Fabry-Perot laser diode (FP LD) oscillating in a multi-mode. Using WDM-PON was proposed.

Using this method, there is an advantage of implementing WDM-PON using a low-cost Fabry-Perot laser diode (FP LD), and the wavelength locking of the Fabry-Perot laser diode (FP LD) is a wavelength filtered through the AWG. Because it occurs in the AWG or Fabry-Perot laser diode (FP LD) it has a strong characteristic to change the wavelength according to the temperature.

However, a problem arises in that the EDFA is separately inserted into the broadband incoherent light source.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention has been made to solve various drawbacks and problems caused by the conventional wavelength division multiplex passive optical subscriber network implementation method, and an object thereof is injection locking of a Fabry-Perot laser diode (FP LD). Very low cost by implementing WDM-PON with NxN AWG and Fabry-Perot laser diode (FP-LD) only using Fabry-Perot laser diode (FP LD) own beam as a non-coherent beam to induce The present invention provides a wavelength division multiplex passive optical subscriber network implementation method.

It is another object of the present invention to construct a WDM-PON using only low-cost Fabry-Perot laser diode (FP LD) light source and multi-mode oscillation and NxN AWG, and subtract one channel for optical signal transmission from NxN AWG. The beams of the four channels are used as incoherent beams for injection locking of Fabry-Perot laser diodes (FP LDs) so that the N-1 beams are mixed through an Nx1 optocoupler to create a non-coherent beam. Insensitive to change, no additional control circuitry is required for temperature compensation, enabling a very low cost WDM-PON configuration, but in particular an ultra-low-cost, wavelength-division, multiple-passive passive optical subscriber network that does not require incoherent external injection beams To provide an implementation.

Ultra low-cost wavelength division multiplexing passive optical subscriber network implementation method for achieving the above object uses a plurality of low-cost Fabry-Perot laser diode (FP LD ₁ ~ FP LD _N ) as a light source of the transmitting end, the Fabry Perot laser diode (FP LD ₁ FP LD _N ) multiplexes the optical signal output by the NxN wavelength division multiplexer (NxN AWG1), and mixes the beams from the N-1 outputs with the N-1x1 optocoupler. In addition to being applied to a ferret laser diode (FP LD) transmitter, the multiplexed signal is demultiplexed through a 1xN wavelength division demultiplexer (1xN AWG) to be received by a plurality of PIN photodetectors (PD1 to PDN). do.

The present invention provides an NxN AWG, Fabry-Perot laser diode (FP-) using a Fabry-Perot laser diode (FP LD) itself as a non-coherent beam for inducing injection locking of the Fabry-Perot laser diode (FP LD). Ultra low cost can be realized by constructing WDM-PON only with LD) and WDM-PON is composed of low-cost Fabry-Perot laser diode (FP LD) light source and NxN AWG that generate in multiple modes, and optical signal transmission is performed in NxN AWG. N-1 channel beams minus one channel are used as incoherent beams for injection locking of Fabry-Perot laser diodes (FP LDs), where N-1 beams are passed through the Nx1 optocoupler. It is insensitive to temperature changes by mixing to create incoherent beams, which eliminates the need for additional control circuitry for temperature compensation, making it possible to configure very low cost WDM-PONs, especially non-coherent. There is a particular advantage that no star external injection beam is required.

1 is a structural diagram for explaining the basic principle of the present invention,
2 is a diagram showing a transfer characteristic table for a wavelength of N × N AWG;
3 is a conceptual diagram illustrating wavelength division of an NxN wavelength division multiplexer for explaining the basic principle of FIG. 1;
4 is a graph showing optical power according to a wavelength after the Fabry-Perot laser diode (FP LD) injection locking operation of FIG. 1 is completed,
FIG. 5 is a diagram illustrating a configuration of a wavelength division multiplexing passive optical subscriber network to which a semiconductor optical amplifier is added in FIG. 1.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the ultra-low price wavelength division multiplex passive optical subscriber network implementation method of the present invention.

1 is a structural diagram for explaining the basic principle of the present invention, FIG. 2 is a diagram showing a transmission characteristic table for the wavelength of NxN AWG, Figure 3 is a wavelength of the NxN wavelength division multiplexer for explaining the basic principle of FIG. 4 is a graph illustrating optical power according to a wavelength after the Fabry-Perot laser diode (FP LD) injection locking operation of FIG. 1 is completed, and FIG. 5 is a wavelength division multiplex method in which a semiconductor optical amplifier is added in FIG. As an exemplary configuration of a passive optical subscriber network, the ultra low-cost wavelength division multiplex passive optical subscriber network implementation method of the present invention uses a plurality of low-cost Fabry-Perot laser diodes (FP LD ₁ to FP LD _N ) as a light source of a transmitter. the Fabry-Perot laser diode (FP LD ₁ ~ _N FP LD) beams from the N-1 outputs the multiplexed optical signal output to the NxN wavelength division multiplexer (NxN AWG1) N-1x1 optical Connectors from Multiplexed photodetectors by applying a mixed beam back to the Fabry-Perot laser diode (FP LD) transmitter through an optical circulator and demultiplexing the multiplexed signal through a 1xN wavelength division demultiplexer (1xN AWG). It is implemented by receiving with (PD1-PDN).

Here, the Fabry-Perot laser diodes FP LD ₁ to FP LD _N may have an arbitrary wavelength band, and the PIN photodetectors PD1 to PDN may include a circuit capable of adjusting a decision threshold.

In addition, it is preferable to add an optical amplifier to increase the output of the N-1x1 optical coupler.

Next will be described in detail the operation of the ultra-low price wavelength division multiplex passive optical subscriber network implementation method of the present invention implemented as described above.

A structure for explaining the basic principle of the present invention is shown in FIG. The transfer characteristics of the NxN AWG used are shown in FIG. 2. NxN AWG input beams generated by Fabry-Perot laser diode (FP LD) are input, and these beams are respectively output to the NxN AWG output terminal by the transfer characteristic of FIG. 2. As can be seen from FIG. 2, the first output terminal outputs a beam having a wavelength of λ ₁ ¹ λ ₂ ² λ ₃ ^3... Λ _N-1 ^N-1 λ _N ^N. The second output terminal outputs a beam of λ ₂ ¹ λ ₃ ² λ ₄ ^3... Λ _N ^{N -1} λ _N-1 ^N wavelength, and the beam is output to the remaining output terminals of the NxN AWG as a cyclic type. It can be seen that.

The 2nd, 3rd, ... N-1, Nth output beams except the beam of the first output stage are combined by the (N-1) x1 optocoupler of FIG. 1, and the phase information of the beams is It is broken by summing and output to a pseudo incoherent beam. Of course, each Fabry-Perot laser diode (F-P LD) is being modulated, but if the input N is somewhat large, it is enough to make an incoherent beam.

3 is a graphical representation of the pass characteristics for wavelength l when the Fabry-Perot laser diode (F-P LD) is first turned on and passes through the NxN AWG. In FIG. 3, the beam having a thick pass band is a component transmitted toward the 1 × N AWG through the optical circulator and the optical fiber in FIG. 1. The remainder of this component is summed by the (N-1) x1 optocoupler and is incident through the optical circulator back towards each Fabry-Perot laser diode (F-P LD).

This beam induces injection locking of each Fabry-Perot laser diode (F-P LD). The injection lock will stop at the point where each Fabry-Perot laser diode (FP LD) creates a pseudo single mode, as shown in FIG. 4, and the optical power in the side mode is totally summed and balanced at the minimum point inducing the injection lock. All.

The invention can ensure that the Fabry-Perot laser diode (F-P LD) used is operated in a laser with a certain high power. That is, the size of the beam incident into the (N-1) x1 cuff should be large enough to induce injection locking. However, when less than the minimum optical power that induces the injection lock, as shown in FIG. 5, a semiconductor optical amplifier (SOA) is inserted to sufficiently amplify the beam, and then the injection lock of the Fabry-Perot laser diode (FP LD) is prevented. You can create a beam for it.

While the present invention has been described as a preferred embodiment, the present invention is not limited thereto, and various modifications can be made without departing from the gist of the invention.

FP LD, FP LD ₁ to FP LD _N : Fabry-Perot laser diode
NxN AWG, NxN AWG ₁ Wavelength Division Multiplexer
PD ₁ PD _N PIN photodetector

Claims (4)

NxN wavelength division of the optical signal output from the Fabry-Perot laser diodes (FP LD ₁ to FP LD _N ) using a plurality of low-cost Fabry-Perot laser diodes (FP LD ₁ to FP LD _N ) as the light source of the transmitter. Multiplexing with multiplexer (NxN AWG1), N-1 output beams are mixed with N-1x1 optocoupler, and then applied to the Fabry-Perot laser diode (FP LD) transmitter through the optical circulator. What is claimed is: 1. A method for implementing an ultra-low-cost wavelength division multiplexing passive optical subscriber network implemented by demultiplexing a received signal through a 1 × N wavelength division demultiplexer (1 × N AWG) and receiving the received signal through a plurality of PIN photodetectors PD1 to PDN;
The Fabry-Perot laser diodes (FP LD ₁ to FP LD _N ) may have any wavelength bands;
The PIN photodetectors (PD1 ~ PDN) is an ultra-low price wavelength division multiplex passive optical subscriber network implementation method characterized in that it comprises a circuit for adjusting the threshold value. delete delete The method of claim 1, wherein an optical amplifier is added to increase the output of the N-1x1 optical coupler.

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