KR101038219B1 - Broadband light source for use in wavelength division multiplexed-passive optical network - Google Patents

Abstract

A broadband light source for a wavelength division multiplexed-passive optical network (WDM-PON), comprising: an erbium doped fiber for amplifying an input light, and a first pump light coupled to the erbium-doped fiber; And an arrayed waveguide grating (AWG) mirror connected to the first optical coupler and the erbium-doped optical fiber and reflecting only the pump light having a predetermined wavelength among the pump light to be transmitted to the erbium-doped optical fiber.

WDM-PON, Broadband Light Source, AWG Mirror

Description

BROADBAND LIGHT SOURCE FOR USE IN WAVELENGTH DIVISION MULTIPLEXED-PASSIVE OPTICAL NETWORK}

The present invention relates to a broadband light source for use in a wavelength division multiplex passive optical network.

Broadband light sources are widely used in various fields, such as wavelength division multiplexed passive optical networks (WDM-PON), optical measurement, optical sensing, or gyroscopes.

Briefly, a wavelength division multiplexing passive optical network, which is a main field of use, will provide an ultra-high speed broadband communication service using a unique wavelength assigned to each subscriber. Therefore, since only the corresponding subscriber receives signals of different wavelengths, security is excellent, separate communication services can be provided for each subscriber, and the expansion of communication capacity can be easily accommodated.

Conventionally, a method of implementing a WDM-PON by using a DFB-LD (Distributed Feedback-Laser Diode) device, wherein a central office (CO) and subscriber terminals (CO) have light sources having different wavelengths, respectively. This has been proposed. However, this method has a problem in that it is difficult to commercialize in terms of cost because the DFB-LD device is expensive, and also requires a complicated temperature control technology. Accordingly, a wavelength-locked optical signal that induces wavelength locking by injecting an incoherent broadband light source (BLS) into a low-cost Fabry-Perot laser diode (FP-LD), thereby realizing a WDM optical signal. The technique using is widely used.

Such a broadband light source may be configured in various forms. In the case of using a semiconductor, a broadband light source having a compact size can be configured using a super luminescent LED or a reflective semiconductor optical amplifier (RSOA), but the output may be reduced due to coupling loss. The disadvantage is that it is difficult to increase.

In contrast, in the configuration using Erbium Doped Fiber (EDF), two important bands (e.g., C-band and L-band) used in optical communication are amplified Spontaneous Emission: ASE) can be easily obtained. Accordingly, two-way communication between the base station and the subscriber device can be implemented.

Meanwhile, in order to develop a WDM-PON having a giga-class data transmission characteristic, a high power broadband light source is required because the power of non-coherent light injected into the FP-LD needs to be increased. In this case, there is a lagging phenomenon due to reflection at the splicing point as a problem to be overcome for the implementation of the high power broadband light source. In addition, it is necessary to increase the pump power for high power.

Some embodiments of the present invention provide a broadband light source capable of increasing pump power to implement a broadband light source having high power characteristics.

In addition, another embodiment of the present invention provides a broadband light source for reducing the lamination phenomenon due to reflection at the splicing point to implement a broadband light source having a high output characteristics.

As a technical means for achieving the above-described technical problem, the broadband light source according to the first aspect of the present invention is input in a broadband light source for a wavelength division multiplexed passive optical network (WDM-PON), Erbium-doped optical fiber for amplifying light, a first optical coupler for coupling a first pump light to the erbium-doped optical fiber and an erbium-doped optical fiber to reflect only the pump light of a predetermined wavelength among the pump light to add the erbium It includes an arrayed waveguide grating (AWG) mirror that transmits to the optical fiber.

The broadband light source according to the second aspect of the present invention is a broadband light source for a wavelength division multiplexed-passive optical network (WDM-PON), and amplifies only pump light having a predetermined wavelength through an erbium-doped optical fiber. A spectrum generating unit for generating an AMP (Amplified Spontaneous Emission) spectrum and a spectrum amplifying unit for amplifying the output of the spectrum, the spectrum generation unit reflects only the pump light of a predetermined wavelength of the pump light to transmit to the erbium-doped optical fiber (AWG) Arrayed Waveguide Grating) mirror.

The broadband light source according to the third aspect of the present invention is a broadband light source for a wavelength division multiplexed-passive optical network (WDM-PON), the first band light source for providing a light source of the C band, L A second band light source providing a light source of a band, a broadband filter multiplexing the light of the C band and the L band, and reflecting only a predetermined wavelength among light transmitted from the first band light source and the second band light source through the broadband filter; And an arrayed waveguide grating (AWG) mirror, wherein the wideband filter demultiplexes the light reflected from the AWG mirror and transmits the demultiplexed light to the first band light source or the second band light source, and each of the band light sources is demultiplexed. The amplified spontaneous emission (ASE) spectrum is generated by amplifying the light through an erbium-doped fiber.

According to the above-described problem solving means of the present invention, since only the wavelength used for the actual optical communication of the entire wavelength can be amplified, it is possible to efficiently use the power of the pump laser diode to implement a high power broadband light source.

In addition, according to the above-described problem solving means of the present invention, by configuring the broadband light source in a multi-step, such as a spectrum generator, a spectrum amplification unit, it is possible to minimize the laser phenomenon caused by reflection at the splicing point. As a result, a high power broadband light source can be realized.

In addition, one AWG mirror can generate spectra for two broadband light sources, simplifying the construction of the broadband light source and reducing the cost.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

1 is a diagram for describing bidirectional communication in a wavelength division multiplex passive optical network 100 to which the present invention is applied.

The wavelength division multiplexing passive optical network 100 includes a central base station 110 and a subscriber device 130, a remote node 120 and an optical cable 140 connecting the central base station 110 and each subscriber device 130. It includes.

The central base station 110 includes an A band light source 111 (BLS: Broadband Light Source), a B band light source 112 (BLS), a light source splitter 113, a first 1 N optical multiplexer / demultiplexer 114, and a transmitter / receiver ( 115).

The remote node 120 includes a second 1′N optical multiplexer / demultiplexer 121, and the optical subscriber device 130 includes a transmitter / receiver 131.

The A-band light source 111 provides an A-band optical signal used as a downlink optical signal, and mainly an incoherent light source is used. The A band light source 111 generates an A band optical signal and provides it to the light source distributor 113.

The B band light source 112 provides a B band optical signal used as an uplink optical signal, and like the A band light source 111, mainly an incoherent light source is used. The B band light source 112 generates a B band optical signal and transmits the generated B band light signal to the light source distributor 113.

The light source distributor 113 receives the A band optical signal from the A band light source 111 and transmits the A band optical signal to the first 1 ⅹN optical multiplexer / demultiplexer 114 of the central base station 110. In addition, the first 1 ⅹN optical multiplexer / demultiplexer 114 of the central base station 110 receives the wavelength-locked A band optical signal and transmits to the optical cable 140 connected to the remote node 120.

The light source distributor 113 receives the B band optical signal from the B band light source 112 and transmits the B band optical signal to the second 1′N optical multiplexer / demultiplexer 121 of the remote node 120 through the optical cable 140. In addition, the wavelength-locked B-band optical signal is received from the second 1ⅹN optical multiplexer / demultiplexer 121 of the remote node 120 and transmitted to the first 1ⅹN optical multiplexer / demultiplexer 114 of the central base station 110. .

The first 1 ⅹN optical multiplexer / demultiplexer 114 separates the A-band optical signal received from the light source distributor 113 for each wavelength and injects it into the transmitter of the transmitter / receiver 115 of the central base station.

The transmitter of the transmitter / receiver 115 is, for example, a Fabry Perot Laser Diode (FP-LD), which generates a downlink optical signal for transmission to each subscriber.

Specifically, when the A-band optical signal separated for each wavelength is injected into the transmitter of the transmitter / receiver 115, the wavelength and other frequency components of the injected optical signal are suppressed, and the same wavelength as the injected optical signal is fixed (locked). As a result, the A-band downlink optical signal whose wavelength is locked is output.

The receiver of the transmitter / receiver 115 receives a wavelength-locked B-band uplink optical signal received from the subscriber device 130 and converts the signal into an electrical signal. A photo diode (PD) may be used. have.

The second 1ⅹN optical multiplexer / demultiplexer 121 of the remote node 120 separates the B-band optical signal received from the light source distributor 113 for each wavelength and injects the B-band optical signal into the transmitter / receiver 131 of the subscriber device 130. . As the second 1 ⅹN optical multiplexer / demultiplexer 121, an arrayed waveguide grating (AWG) may be used, similarly to the first 1 ⅹN optical multiplexer / demultiplexer 114.

The transmitter of the transmitter / receiver 121, for example, uses a Fabry-Perot laser diode (FP-LD), and generates an uplink optical signal to be transmitted to the central base station.

In detail, when the B-band optical signal separated for each wavelength is injected into the transmitter of the transmitter / receiver 121, the wavelength and other frequency components of the injected optical signal are suppressed, and the same wavelength as the injected optical signal is fixed (locked). As a result, the B-band upward optical signal whose wavelength is locked is output.

The receiver of the transmitter / receiver 131 receives a wavelength-locked B-band uplink optical signal received from the central base station and converts the received optical signal into an electrical signal, and may be configured as a photo diode (PD).

Now, a configuration of a conventionally used broadband light source will be described.

2 is a view showing a detailed configuration of a broadband light source that is commonly used.

The broadband light source 200 includes an erbium-doped optical fiber 220 for amplifying the input light, an optical coupler 210 for coupling the pump light output from the pump laser diode (Pump LD) to the erbium-doped optical fiber 220, and reflecting light. Gold mirror 230, and isolator 240 for fixing the direction of the flow of light.

At this time, pump light having a wavelength of 980 nm or pump light having a wavelength of 1480 nm may be used as the pump light. In addition, since the pump light is amplified while passing through the erbium-doped optical fiber 220, an amplified spontaneous emission light (ASE) can be obtained.

In the conventional broadband light source 200, all the ASE spectra generated by the erbium-doped optical fiber 220 are reflected through the gold mirror 230. That is, in addition to the wavelength corresponding to the 32 channels used in the actual WDM-PON, the spectrum is also generated for the wavelength corresponding to the frequency band not actually used, there is an inefficient aspect.

Therefore, the present invention uses the configuration to increase the efficiency by generating or amplifying only the wavelength actually required.

3 is a view showing a detailed configuration of a broadband light source according to an embodiment of the present invention.

The broadband light source 300 includes an erbium-doped optical fiber 320 for amplifying input light, an optical coupler 310 for coupling the pump light output from the pump laser diode to the erbium-doped optical fiber 320, and an AWG mirror 330 for reflecting light. ), An isolator 340 for fixing the flow direction of light.

In the present invention, the amplification can be performed only for the wavelength corresponding to 32 channels used in the actual WDM-PON. To this end, in the present invention, only the wavelength corresponding to a predetermined number of channels is reflected using the AWG mirror 330.

The AWG mirror 330 reflects only a predetermined number of wavelengths and transmits the wavelength to the erbium-doped optical fiber 320. To this end, it comprises an arrayed waveguide grating (AWG) and a plurality of mirrors 332 connected to the output end of the arrayed waveguide grating. In this case, the number of mirrors 332 is determined according to the number of channels used in the WDM-PON. According to an embodiment, thirty-two mirrors are each connected to an output end. In addition, a mirror may be formed by performing a gold coating on the output terminal of the arrayed waveguide grating.

In this way, a spectrum is generated at a wavelength actually used, and a wavelength of an undesired band (for example, 1533 to 1560 nm in the C-band and 1573 to 1600 nm in the L-band) is not reflected. The reflected ASE spectrum of the specific wavelength is amplified again through the erbium-doped optical fiber 320. Therefore, the ASE spectrum of the wavelength actually used can be amplified and the power consumption of the pump laser diode for amplifying a relatively unnecessary wavelength can be prevented.

4 is a graph illustrating output light by a broadband light source according to an exemplary embodiment of the present invention.

The left graph is a graph showing the AWG mirror reflectance characteristics in the L-band, and the right graph is a graph of the AWG mirror reflectance characteristics in the C-band. In accordance with the WDM-PON with 32 channels, the AWG mirror 330 is an AWG that decomposes the ASE spectrum into 32 wavelengths, and, if it contains 32 mirrors, only the ASE spectrum corresponding to 32 wavelengths with relatively high reflectance. Is amplified, and the ASE spectra of the remaining wavelengths are relatively less amplified.

5A and 5B are diagrams showing a detailed configuration of a broadband light source according to an embodiment of the present invention.

5A is a broadband light source, unlike the broadband light source of FIG. 3, the advancing direction of the pump light coincides with the advancing direction or output direction of the isolator. In the case of the broadband light source of FIG. 3, the advancing direction of the pump light is different from the output direction, and thus the counter-pumping structure is referred to. The broadband light source of FIG. 5A is called a co-pumping structure.

The broadband light source of FIG. 5A also includes an erbium-doped optical fiber 520 for amplifying the input light, an optical coupler 510 for coupling the pump light output from the pump laser diode to the erbium-doped optical fiber 520, and an AWG mirror 540 for reflecting light. ), An isolator 530 fixing the flow direction of the light. Also in this embodiment, the AWG mirror 540 reflects only a predetermined wavelength and transmits it to the erbium-doped optical fiber 520.

The broadband light source of FIG. 5B combines the broadband light sources of FIGS. 3 and 5A and is referred to as a two-way pumping structure.

The broadband light source of FIG. 5B also includes an erbium-doped optical fiber 560 for amplifying the input light, first and second optical couplers 550 and 570 for coupling the pump light output from the pump laser diode to the erbium-doped optical fiber 560. And an AWG mirror 590 for reflecting the light, and an isolator 580 for fixing the flow direction of the light. Also in this embodiment, the AWG mirror 590 reflects only a predetermined wavelength and transmits it to the erbium-doped optical fiber 560.

6 is a diagram illustrating a detailed configuration of a broadband light source according to another embodiment of the present invention.

The broadband light source 600 includes a spectrum generator 610 in which pump light having a predetermined wavelength reflected through the AWG mirror 616 is amplified by an erbium-doped optical fiber, and a spectrum amplifier for amplifying an output signal of the spectrum generator 610. 620.

Another challenge to implement high power broadband light sources is to minimize the lasing caused by reflections at the splicing point. In the case of low power broadband light sources, because of the relatively low driving power, a cavity is formed by reflections caused by splicing points, connectors or individual passive elements, which causes the lasing phenomenon. The effect does not work much. However, in the case of high power broadband light sources, the cavity is easily formed even by low reflection, and when the threshold value is exceeded, the lasing occurs. This generated laser significantly weakens the fluctuation or flatness characteristics of the output level of the overall ASE spectrum.

In this case, the spectrum generator 610 may include a configuration of various broadband light sources described with reference to FIG. 3 or 5. That is, the AWG includes a mirror 616, an amplifier 614, and an isolator 612. In this case, the amplifier 614 may include an erbium-doped optical fiber. Accordingly, the spectrum generator 610 amplifies and outputs the ASE spectrum having a predetermined wavelength reflected by the AWG mirror 616 through the erbium-doped optical fiber.

On the other hand, the upper limit of the output of the spectrum generator 610 is to be the output value before the generation of the laser. That is, the output value at which lasing starts to occur is obtained through experimental data and the like, and the configuration of the amplifier 614 is set so that the output value is lower than that. The output spectrum of the spectrum generator 610 is further amplified by the spectrum amplifier 620. That is, the spectrum generator 610 is configured to have an output value somewhat lower than the desired output value, and the output value that falls short of the desired output value is supplemented by the spectrum amplifier 620.

The spectrum amplifier 620 outputs the first isolator 622 receiving the output spectrum of the spectrum generator 610, the amplifier 626 amplifying the output of the first isolator 622, and the amplifier 626. It includes a second isolator 624 to receive and output. In this case, the amplifier 626 may include an erbium-doped optical fiber.

The first and second isolators 622 and 624 serve to prevent cavity formation. That is, since the output spectrum transmitted from the spectrum generator 610 is amplified by the amplifier 626, the reflection of the output spectrum is again reflected by the spectrum amplifier 620, thereby preventing razing formed by the reflection. have.

Meanwhile, according to the exemplary embodiment, one of the isolator 612 of the spectrum generator 610 and the first isolator 622 of the spectrum amplifier 620 may be omitted, and the broadband light source may be configured. That is, only one isolator may be included at the connection point between the spectrum generator 610 and the spectrum amplifier 620.

According to such a configuration, it is possible to solve a problem occurring when the high power broadband light source is implemented.

7 is a diagram illustrating a detailed configuration of a broadband light source according to another embodiment of the present invention.

The broadband light source 700 includes a spectrum generator 710 in which pump light having a predetermined wavelength reflected through the AWG mirror 718 is amplified by an erbium-doped optical fiber, and a spectrum amplifier for amplifying an output signal of the spectrum generator 710. 720.

 In this case, the spectrum generator 710 includes an AWG mirror 718, a broadband filter 716 for multiplexing / demultiplexing light of the C band and the L band, a first broadband light source generator 712, and a second wideband light source. Part 714 is included.

Also, the spectrum amplifier 720 includes a first broadband light source amplifier 722 and a second broadband light source amplifier 724.

In the present exemplary embodiment, one broadband filter 716 filters an ASE spectrum having a predetermined wavelength reflected by the AWG mirror 718 to the first broadband light source generator 712 and the second broadband light source generator 714. to provide. Therefore, the configuration can be simplified and the cost can be reduced as compared with the case of FIG. 6 having an AWG mirror for each broadband light source.

The first broadband light source generator 712 and the second broadband light source generator 714 include the amplifiers 712_1 and 714_1 and the isolators 712_2 and 714_2, respectively, like the spectrum generator 610 of FIG. 6.

In addition, the first wideband light source amplifying unit 722 and the second wideband light source amplifying unit 724 included in the spectrum amplifying unit 720 are the amplifying units 722_1 and 724_1, like the spectral amplifying unit 620 of FIG. Isolators 722_2, 722_4, 724_2, and 724_3, respectively. In addition, a gain flattening filter GFF 722_3 may be further included according to a user's selection.

According to such a configuration, it is possible to generate spectra for two broadband light sources through one AWG mirror. In addition, since each broadband light source is configured by dividing the spectrum generator and the spectra amplifier, the problem mentioned in FIG. 6 can be solved.

8 is a diagram illustrating a detailed configuration of a broadband light source according to another embodiment of the present invention.

In the present embodiment, a first band light source 810 for providing a light source of the C band, a second band light source 820 for providing a light source of the L band, and a broadband filter for multiplexing / demultiplexing light of the C band and the L band ( 830, an AWG mirror 840 reflecting light transmitted from the first band light source 810 and the second band light source 820, respectively. The broadband light source shown in FIG. 7 is further embodied.

In this case, the first band light source 810 may include first and second optical couplers 812 and 816 and first and second isolators 814 and 817, according to an exemplary embodiment. In addition, it may further include a gain planarization filter (GFF, 813).

In addition, the second band light source 820 may include optical couplers 822 and 823, and first and second isolators 825 and 827, according to embodiments.

As in the previous embodiment, since only the predetermined wavelength of the light transmitted from the first band light source 810 or the light transmitted from the second band light source 820 is reflected, power consumption may be minimized. In addition, one AWG mirror can generate spectra for two broadband light sources. In addition, since each broadband light source is configured by dividing the spectrum generator and the spectra amplifier, the problem mentioned in FIG. 6 can be solved.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

1 is a diagram illustrating bidirectional communication in a wavelength division multiplex passive optical network to which the present invention is applied.

2 is a view showing a detailed configuration of a broadband light source that is commonly used.

3 is a view showing a detailed configuration of a broadband light source according to an embodiment of the present invention.

4 is a graph illustrating output light by a broadband light source according to an exemplary embodiment of the present invention.

5A and 5B are diagrams showing a detailed configuration of a broadband light source according to an embodiment of the present invention.

6 is a diagram illustrating a detailed configuration of a broadband light source according to another embodiment of the present invention.

7 is a diagram illustrating a detailed configuration of a broadband light source according to another embodiment of the present invention.

8 is a diagram illustrating a detailed configuration of a broadband light source according to another embodiment of the present invention.

Claims (14)

In a broadband light source for a wavelength division multiplexed-passive optical network (WDM-PON), Erbium Doped Fiber, which amplifies the input light, A first optical coupler for coupling a first pump light to the erbium-doped optical fiber, An arrayed waveguide grating (AWG) mirror connected to the erbium-doped optical fiber and reflecting only one or more preset wavelengths to the erbium-doped optical fiber, A first isolator for outputting light generated through the erbium-doped optical fiber, A second isolator receiving the output light output from the first isolator, An amplifier for amplifying the output of the second isolator; Third isolator for receiving and outputting the output of the amplifier Broadband light source comprising a. The method of claim 1, The AWG mirror comprises an arrayed waveguide grating having a predetermined number of output stages and A plurality of mirrors each connected to an output end of the arrayed waveguide grating to reflect light Broadband light source comprising a. delete delete delete In a broadband light source for a wavelength division multiplexed-passive optical network (WDM-PON), A spectrum generator for amplifying only pump light having a predetermined wavelength through an erbium-doped fiber to generate an ASE (Amplified Spontaneous Emission) spectrum; Including a spectral amplifier for amplifying the output of the spectrum, The spectrum generator reflects only pump light having a predetermined wavelength among the pump light beams and transmits the AWG (Array Waveguide Grating) mirror to the erbium-doped optical fiber. Broadband light source comprising a. The method of claim 6, And the spectrum generator outputs a spectrum having an output value smaller than an output value at which lasing starts to occur. The method of claim 6, The AWG mirror comprises an arrayed waveguide grating having a predetermined number of output stages and A plurality of mirrors each connected to an output end of the arrayed waveguide grating to reflect light Broadband light source comprising a. The method of claim 6, The spectral amplifier comprises: a first isolator for receiving a spectrum output from the spectrum generator; An amplifier for amplifying the output of the first isolator; A second isolator for receiving and outputting the output of the amplifier Broadband light source comprising a. The method of claim 9, The amplifying unit is a broadband light source for performing amplification through the erbium-doped optical fiber. In a broadband light source for a wavelength division multiplexed-passive optical network (WDM-PON), A first band light source providing a C band light source, A second band light source providing an L band light source, A broadband filter multiplexing the light of the C band and the L band, An arrayed waveguide grating (AWG) mirror reflecting only a predetermined wavelength among light transmitted from the first band light source and the second band light source through the broadband filter; The broadband filter demultiplexes the light reflected from the AWG mirror and transmits the demultiplexed light to the first band light source or the second band light source, respectively. Wherein each of the band light sources amplifies the demultiplexed light through an erbium-doped optical fiber to generate an ASE (Amplified Spontaneous Emission) spectrum. The method of claim 11, The AWG mirror comprises an arrayed waveguide grating having a predetermined number of output stages and A plurality of mirrors each connected to an output end of the arrayed waveguide grating to reflect light Broadband light source comprising a. The method of claim 11, Each broadband light source includes an erbium-doped fiber that amplifies the input light; An optical coupler for coupling pump light to the erbium-doped optical fiber Broadband light source comprising a. The method according to any one of claims 2, 8 and 12, And said mirror is formed by performing a gold coating on the output of said arrayed waveguide grating.

Images