WO2011149122A1

WO2011149122A1 - Broadband light source using a fabry-perot filter

Info

Publication number: WO2011149122A1
Application number: PCT/KR2010/003315
Authority: WO
Inventors: 김경민
Original assignee: 주식회사 럭스퍼트
Priority date: 2010-05-25
Filing date: 2010-05-26
Publication date: 2011-12-01
Also published as: KR20110129080A

Abstract

A broadband light source using a Fabry-Perot filter comprises: an eribium doped fibre (eribium doped optical fibre); a first optical coupler for coupling a first pump beam to the eribium doped fibre; and Fabry-Perot unit which is connected to the eribium doped fibre and splits input signal light into specific wavelengths, and reflects the split signal light of specific wavelengths and transmits the same to the eribium doped fibre.

Description

Broadband Light Source with Fabry-Perot Filter

The present invention relates to a broadband light source using a Fabry-Perot filter used 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.

The wavelength division multiplexing passive optical network, which is a main field of use, will be briefly described. The network provides a 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 a subscriber terminal (subscriber terminal) each have a light source having a different wavelength. 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 by 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.

On the other hand, in the configuration using Erbium Doped Fiber (EDF), two important bands (eg, C-band and L-band) used in optical communication are amplified spontaneous due to the characteristics of erbium. Emission can be obtained easily. 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.

To this end, there is a need to efficiently use the power of the pump laser diode by separating the input light for each wavelength used in the actual optical communication and amplifying the light for the corresponding wavelengths.

One embodiment of the present invention by using the Fabry-Perot filter is to separate the input light for each wavelength used in the actual optical communication of the entire wavelength and to amplify the light for the wavelengths, it is possible to efficiently use the power of the pump laser diode The object is to provide a broadband light source using a Fabry-Perot filter.

In addition, an embodiment of the present invention is to provide a broadband light source using a high-power Fabry-Perot filter of low cost, simple structure, and smaller size using a Fabry-Perot filter. There is this.

As a technical means for achieving the above-described technical problem, a broadband light source using a Fabry-Perot filter according to the first aspect of the present invention is Erbium Doped Fiber (Aribium Doped Fiber) to amplify the input light, Erbium-added first pump light A first optical coupler coupled to the optical fiber and the signal light connected to the erbium-doped optical fiber are separated for each specific wavelength, and the Fabry-Perot unit reflects the separated signal light to a erbium-doped optical fiber.

Here, the Fabry-Perot unit includes a Fabry-Perot filter that separates the optical signal for each specific wavelength and a mirror that reflects the separated optical signal of the specific wavelength and transmits the optical signal to the erbium-doped optical fiber.

The apparatus further includes an isolator for outputting light amplified through the erbium-doped optical fiber.

And a second optical coupler for coupling the second pump light to the erbium-doped optical fiber.

In addition, the broadband light source using the Fabry-Perot filter according to the second aspect of the present invention is Erbium Doped Fiber (Aribium Doped Fiber) to amplify the input light, the first optical coupler to couple the first pump light to the Erbium-added Fiber, Erbium The circulator includes a circulator for transmitting the signal light inputted to the additive optical fiber to the Fabry-Perot filter and a Fabry-Perot filter for separating the optical signal received from the circulator by specific wavelengths and delivering the signal to the circulator. An optical signal of a specific wavelength separated from the Fabry-Perot filter is transmitted to the erbium-doped optical fiber.

Here, the first terminal of the circulator is connected to the erbium-doped optical fiber, the second terminal of the circulator is connected to the input terminal of the Fabry-Perot filter, and the third terminal of the circulator is connected to the output terminal of the Fabry-Perot filter will be.

The apparatus further includes a second optical coupler for coupling the second pump light to the erbium-doped optical fiber.

According to the above-described problem solving means of the present invention, by using the Fabry-Perot filter to separate the input light for each wavelength used for the actual optical communication and amplify the light for the wavelengths, the power of the pump laser diode Provided is a broadband light source using a Fabry-Perot filter that can be efficiently used.

In addition, the above-described problem solving means of the present invention provides a broadband light source using a Fabry-Perot filter which is inexpensive, simple in structure, and smaller in size by using a Fabry-Perot filter.

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

2 shows a configuration of a broadband light source that is commonly used.

3 illustrates a configuration of a broadband light source using a Febri-Perot filter according to an embodiment of the present invention.

FIG. 4 illustrates a configuration of a broadband light source using a Febri-Perot filter in which a traveling direction of the pump light matches a traveling direction or an output direction of the isolator according to an embodiment of the present invention.

FIG. 5 illustrates a broadband light source using a Fabry-Perot filter having a structure combining the broadband light sources of FIGS. 3 and 4 according to an embodiment of the present invention.

6 illustrates a configuration of a broadband light source using a Febri-Perot filter according to another embodiment of the present invention.

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. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 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.

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 the A band light source 111 (BLS: Broadband Light Source), the B band light source 112 (BLS), the light source distributor 113, the first 1 × N optical multiplexer / demultiplexer 114 and 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 × N optical multiplexer / demultiplexer 114 of the central base station 110. In addition, the wavelength-locked A-band optical signal is received from the first 1 × N optical multiplexer / demultiplexer 114 of the central base station 110 and transmitted 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 first 1 × N optical multiplexer / demultiplexer 114 of the central base station 110 receives the wavelength-locked B-band optical signal from the second 1 × N optical multiplexer / demultiplexer 121 of the remote node 120. To pass).

The first 1 × N 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 110.

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

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 1 × N 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 to the transmitter / receiver 131 of the subscriber device 130. Inject. As the first 1 × N optical multiplexer / demultiplexer 121, an arrayed waveguide grating (AWG) may be used, similarly to the first 1 × N optical multiplexer / demultiplexer 114.

The transmitter of the transmitter / receiver 131 is, for example, a Fabry-Perot laser diode (FP-LD) or a reflective semiconductor optical amplifier, and generates an uplink optical signal to be transmitted to the central base station 110.

In detail, when the B-band optical signal separated for each wavelength is injected into the transmitter of the transmitter / receiver 131, 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). Hereinafter, a broadband light source commonly used through FIG. 2 will be described later.

2 shows a configuration of a broadband light source that is commonly used.

As shown in FIG. 2, the broadband light source 200 combines an erbium-doped optical fiber 220 for amplifying input light and a pump coupler output from the pump laser diode Pump LD to the erbium-doped optical fiber 220. 210, a gold mirror 230 reflecting light, and an isolator 240 fixing the flow direction 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. In other words, the spectrum is generated in addition to the wavelength corresponding to the channel used in the actual WDM-PON, 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.

As shown in FIG. 3, the broadband light source 300 includes an erbium-doped optical fiber 320 for amplifying the input light, an optical coupler 310 for coupling the pump light output from the pump laser diode to the erbium-doped optical fiber 320, Fabry-Perot unit 330 for reflecting light, and isolator 340 for fixing the direction of the flow of light.

According to an embodiment of the present invention, amplification may be performed only for a specific wavelength corresponding to a channel used in an actual WDM-PON. To this end, in the present invention, the Fabry-Perot unit 330 may reflect only a specific wavelength corresponding to a predetermined number of channels.

The Fabry-Perot unit 330 separates the input light by a specific wavelength and reflects the input light to the erbium-doped optical fiber 320. To this end, it includes a Fabry-Perot Filter 332 and a mirror 334 connected to the output terminal of the Fabry-Perot Filter 332. In this case, the mirror 334 may be formed by performing gold coating on the output terminal of the Fabry-Perot filter 332.

The Fabry-Perot filter 332 is a Fabry-Perot resonator such as a solid etalon filter or a narrow pass filter. The Fabry-Perot filter 332 has a characteristic of changing wavelength and reflectance with periodic wavelength dependence. It has the same characteristics with respect to the incident angle of the incident light.

And, as an example of the Fabry-Perot filter 332, in the case of the solid etalon filter coated on both sides of the fused silica to have the same reflectance (free spectral range) in the transmission characteristics for incident light (free The magnitude of the spectral range and peak full width half maximum (FWHM) depends on the thickness of the etalon, the refractive index, the size of the coating reflectivity, the wavelength of the light and the angle of incidence.

Therefore, when the thickness of the etalon, the refractive index, and the size of the coating reflectance are determined, the transmittance and reflectance of the incident light at a specific wavelength change according to the incident angle, and at a specific incident angle, depending on the wavelength.

The Fabry-Perot filter 332 of the present invention using such a feature may separate the input light by a specific wavelength using, for example, a refractive index. For example, the natural emission light is separated by 32 specific wavelengths used for actual optical communication among the entire wavelengths, and the mirror 334 reflects the original path to the filtered light through the Fabry-Perot filter 332. The mirror 334 may be connected to or integrally formed with the output terminal of the Fabry Perot filter 330 by a continuous process.

The signal light of the reflected wavelength is amplified again through the erbium-doped optical fiber 320. Therefore, the signal light of the wavelength actually used is amplified, and the power consumption of the pump laser diode for amplifying a relatively unnecessary wavelength can be prevented.

In addition, the Fabry-Perot filter 332 can be used to provide a high power broadband light source of low cost, simple structure, and smaller size. 4 and 5 show an example in which the basic configuration of the broadband light source 300 is applied.

As shown in FIG. 4, the broadband light source 300 may be configured such that the advancing direction of the pump light coincides with the advancing direction or output direction of the isolator. Here, in the case of the broadband light source 300 of FIG. 3 described above, the advancing direction of the pump light is different from the output direction and is referred to as a counter-pumping structure, and the broadband light source 300 of FIG. 4 is co-pumping. It is called structure.

The broadband light source 300 of FIG. 4 includes an erbium-doped optical fiber 320 for amplifying the input light, an optical coupler 312 for coupling the pump light output from the pump laser diode to the erbium-doped optical fiber 320, and a light reflecting light. Bree-Perot unit 330, isolator 340 for fixing the direction of the flow of light. In this embodiment, the Fabry-Perot unit 330 separates the input light by a specific wavelength and reflects the input light to the erbium-doped optical fiber 320.

As shown in FIG. 5, the broadband light source 300 may be configured to combine the broadband light sources of FIGS. 3 and 4, which is referred to as a bidirectional pumping structure.

Here, the broadband light source 300 includes an erbium-doped optical fiber 320 for amplifying the input light, first and second

optical couplers

312 and 314 for coupling the pump light output from the pump laser diode to the erbium-doped optical fiber 320, Fabry-Perot unit 330 for reflecting light, and isolator 340 for fixing the direction of the flow of light. In this embodiment, the Fabry-Perot unit 330 separates the input light by a specific wavelength and reflects the input light to the erbium-doped optical fiber 320. Meanwhile, the configuration of the broadband light source 300 using the Fabry-Perot filter 332 and the circulator 336 will be described below with reference to FIG. 6.

As shown in FIG. 6, the broadband light source 300 includes an erbium-doped optical fiber 320 for amplifying the input light, an optical coupler 310 for coupling the pump light output from the pump laser diode to the erbium-doped optical fiber 320, The Fabry-Perot filter 332 which separates the light by a specific wavelength, and receives the input light amplified from the erbium-doped optical fiber 320 to be transmitted to the Fabry-Perot filter 332, the Fabry-Perot filter 332 And a circulator 336 for transmitting a specific wavelength received from the erbium-doped optical fiber 320 and an isolator 340 for fixing the direction of light flow.

Here, the first terminal of the circulator 336 is connected to the erbium-doped optical fiber 320, the second terminal of the circulator 336 is connected to the input terminal of the Fabry-Perot filter 332, and the circulator 336 Terminal 3) is connected to the output terminal of the Fabry-Perot filter 332.

Accordingly, the first terminal of the circulator 336 receives the input light amplified from the erbium-doped optical fiber 320, and the second terminal of the circulator 336 is received to the input terminal of the Fabry-Perot filter 332. The input light is transmitted, and the third terminal of the circulator 336 receives the light separated by the specific wavelength from the output terminal of the Fabry-Perot filter 332 and transmits the light to the erbium-doped optical fiber 320.

The Fabry-Perot filter 332 and the circulator 336 as described above may be used in a nasal pumping structure and a bidirectional pumping structure, as described above with reference to FIGS. 4 and 5. See 5.

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. Therefore, it should be understood that the embodiments described above are exemplary in all respects 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.

Claims

In a broadband light source using a Fabry-Perot filter,

Erbium Doped Fiber, which amplifies the input light,

A first optical coupler for coupling a first pump light to the erbium-doped optical fiber, and

A Febri-Perot unit, which is connected to the erbium-doped optical fiber and separates the signal light input by a specific wavelength, reflects the separated signal light of the specific wavelength, and transmits the signal light to the erbium-doped optical fiber.

Broadband light source using a Fabry-Perot filter comprising a.
The method of claim 1,

The Fabry-Perot unit

A Febri-Perot filter for separating the signal light by the specific wavelength and

Broadband light source using a Fabry-Perot filter including a mirror for reflecting the separated signal light of the particular wavelength and transmitting to the erbium-doped optical fiber.
The method according to claim 1 or 2,

A broadband light source using a Febri-Perot filter further comprises an isolator for outputting the light amplified through the erbium-doped optical fiber.
The method of claim 1,

And a second optical coupler for coupling a second pump light to the erbium-doped optical fiber.
In a broadband light source using a Fabry-Perot filter,

Erbium Doped Fiber, which amplifies the input light,

A first optical coupler for coupling a first pump light to the erbium-doped optical fiber,

A circulator for transmitting the signal light connected to the erbium-doped optical fiber to a Febri-Perot filter;

It includes a Fabry-Perot filter that separates the signal light received from the circulator for each specific wavelength and delivers it to the circulator,

The circulator is

The wideband light source using the Fabry-Perot filter is to transmit the signal light of the separated specific wavelength received from the Fabry-Perot filter to the erbium-doped optical fiber.
The method of claim 5,

Terminal 1 of the circulator is connected to the erbium-doped optical fiber, terminal 2 of the circulator is connected to an input terminal of the Febri-Perot filter, and terminal 3 of the circulator is Broadband light source using a Fabry-Perot filter connected to the output.
The method according to claim 5 or 6,

A broadband light source using a Febri-Perot filter further comprises an isolator for outputting the light amplified through the erbium-doped optical fiber.
The method of claim 5,

And a second optical coupler for coupling a second pump light to the erbium-doped optical fiber.