KR20120054373A - Optic transmitter using wavelength division multiplexing - Google Patents

Abstract

An optical transmitter according to an embodiment of the present invention injects a plurality of optical signals having different wavelengths output from a plurality of laser diodes into a single optical path through a plurality of wavelength division multiplex filters, and the plurality of wavelength division multiplexes. A multi-channel optical transmission module, wherein a part of the multi-wavelength optical signal combined through the filters is incident to one monitor receiving element through an optical splitter, and the remaining multi-wavelength optical signal is incident to the optical fiber through a collimator, and the multi-channel optical transmission module And a light output control module configured to control the driving currents input to the plurality of laser diodes by receiving the remaining multi-wavelength optical signal fed back to the monitor light receiving element in order to stably output the multi-wavelength optical signal. The optical receiver according to the present invention is advantageous in integration and cost reduction by using one monitor light receiving element for monitoring an optical signal.

Description

Optical transmitter using wavelength division multiplexing {OPTIC TRANSMITTER USING WAVELENGTH DIVISION MULTIPLEXING}

The present invention relates to an optical transmitter using wavelength division multiplexing.

Wavelength Division Multiplexing (WDM) is a method of transmitting and receiving light of different wavelengths output from multiple optical transceivers through one optical fiber. The wavelength division multiplexing method can transmit a large amount of data at a time, thereby increasing the bandwidth between transmission sections, and instead of using multiple optical fibers, the cost of leasing the optical path by transmitting data using one optical fiber And there is an advantage that can save the maintenance cost.

An object of the present invention is to provide an optical transmitter that is advantageous for integration and cost reduction.

An optical transmitter according to an embodiment of the present invention injects a plurality of optical signals having different wavelengths output from a plurality of laser diodes into a single optical path through a plurality of wavelength division multiplex filters, and the plurality of wavelength division multiplexes. A multi-channel optical transmission module, wherein a part of the multi-wavelength optical signal combined through the filters is incident to one monitor receiving element through an optical splitter, and the remaining multi-wavelength optical signal is incident to the optical fiber through a collimator, and the multi-channel optical transmission module And a light output control module configured to control the driving currents input to the plurality of laser diodes by receiving the remaining multi-wavelength optical signal fed back to the monitor light receiving element in order to stably output the multi-wavelength optical signal.

As described above, the optical receiver according to the present invention is advantageous in integration and cost reduction by using one monitor light receiving element for monitoring the optical signal.

1 is a block diagram of an optical transmitter according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a light output control method of the light output control module illustrated in FIG. 1.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention.

1 is a block diagram of an optical transmitter 100 according to an embodiment of the present invention. Referring to FIG. 1, the optical transmitter 100 includes a multichannel optical transmitter module 120 and an optical power control module 140.

The multi-channel optical transmission module 120 according to the present invention divides a plurality of wavelengths of a plurality of optical signals λ 1, λ 2, λ 3, and λ 4 having different wavelengths output from the plurality of laser diodes LD1 to LD4. Through a plurality of filters (Wavelength Division Multiplexing Filters, 121 ~ 124) is incident to a single optical path. In this case, a part of the multi-wavelength optical signal λ 1 + λ 2 + λ 3 + λ 4 combined through the plurality of wavelength division multiple filters 121 ˜ 124 may be a monitor photo diode through a splitter 125. 126 is incident, and the remaining optical signal is incident on the optical fiber 128 through the collimator 127.

Each of the laser diodes LD1 to LD4 generates optical signals λ1, λ2, λ3, and λ4 having the same wavelength as the light injected from the outside of the input driving currents i1 to i4. The light injected may be injected from a wavelength-locked Fabric-Perot Laser Diode (FP-LD), a Semiconductor Optical Amplifier (SOA), a Reflective Semiconductor Optical Amplifier (RSOA), or the like.

In some embodiments, each of the laser diodes LD1 to LD4 may be an edge emitting laser diode.

Although there are four laser diodes shown in FIG. 1, the present invention is not necessarily limited thereto. The number of laser diodes according to the present invention is two or more.

Each of the wavelength division multiplex filters 121 ˜ 124 selects the optical signals λ 1, λ 2, λ 3, and λ 4 output from each of the laser diodes LD 1 to LD 2 and enters a single path.

The optical separator 125 transmits a part of the incident multi-wavelength optical signal λ 1 + λ 2 + λ 3 + λ 4 to the monitor light receiving element 126, and collimates the remaining multi wavelength optical signal λ 1 + λ 2 + λ 3 + λ 4. Forward to 127.

The monitor light receiving element 126 converts the incident multi-wavelength optical signal lambda 1 + lambda 2 + lambda 3 + lambda 4 into a current.

The collimator 127 adjusts the divergence angle of the multi-wavelength optical signal λ 1 + λ 2 + λ 3 + λ 4 to enter the optical fiber 128.

As described above, the multiple optical transmission module 120 of the present invention includes a plurality of laser diodes LD1 to LD4 for generating a plurality of optical signals and one monitor light receiving element 126 for monitoring the generated optical signals. It includes.

The light output control module 140 according to the present invention has a multi-wavelength incident on the monitor light receiving element 126 in order to stably output optical signals λ 1 + λ 2 + λ 3 + λ 4 in the multi-channel optical transmission module 120. The optical signal is fed back to control driving currents i1 to i4 input to the plurality of laser diodes LD1 to LD4.

The transimpedance amplifier 141 is configured to convert the monitor current input from the monitor light receiving element 126 of the multi-channel optical transmission module 120 into a voltage (hereinafter, the monitor signals P _mPD = f (P _{λ 1} , P _{λ 2} , P). _λ3 , P _λ4 )) and amplify.

The automatic power controller 142 generates control signals P1 to P4 for controlling the laser diode drivers LDD1 to LDD4 using the monitor signal P _mPD of the transimpedance amplifier 141. That is, the automatic power controller 142 receives the multi-wavelength optical signal λ 1 + λ 2 + λ 3 + λ 4 incident on the monitor light receiving element 126 and feeds back the laser diodes LD 1 to LD 4. Drive currents i1 to i4 of the < RTI ID = 0.0 >

In an embodiment, the automatic power controller 142 may increase all driving currents i1 to i4 equally in response to the monitor signal P _mPD . In other words, the automatic power controller 142 may increase the current in batches for all channels.

In another embodiment, the automatic power controller 142 may monitor the optical signal of each channel through one monitor light receiving element 126.

Each of the laser diode drivers LDD1 to LDD4 outputs driving currents i1 to i4 to the laser diodes LD1 to LD4 in response to each of the control signals P1 to P4.

As described above, the optical output control module 140 of the present invention feeds back the optical signal incident to the monitor light receiving element 126, thereby collectively aligning the laser diodes LD1 to LD4 of the multi-channel optical transmission module 120. Control or individual control.

In summary, the optical transmitter 100 according to the present invention has one monitor light receiving element 126 to monitor the generated optical signal, which is advantageous for integration. Therefore, even if the optical transmitter 100 according to the present invention is implemented as a low cost surface emitting laser diode, it is possible to monitor the light output.

In addition, the optical transmitter 100 according to the present invention may reduce the processing cost by using one monitor light receiving element 126 and simplify the structure of the multi-channel optical transmitter module 120.

Furthermore, the optical transmitter 100 according to the present invention can monitor for each channel, thereby increasing the optical alignment margin by an active optical alignment method.

In addition, the optical transmitter 100 according to the present invention may reduce the tracking error due to temperature change by placing the monitor light-receiving grandson 126 in front of the laser diodes LD1 to LD4.

FIG. 2 is a diagram illustrating a light output control method of the light output control module 140 shown in FIG. 1. Referring to FIG. 2, the optical output control module 140 may monitor the optical signal output of the laser diodes LD1 to LD4 for each wavelength by selecting a time point at which the power output is turned on in the communication protocol.

For example, the monitor current of the monitor light receiving element 126 is fed back only when the control signals P1 to P4 are independently powered on for each time frame, so that the control signals P1 to P4 may be identified. Can be.

In addition, the monitor current of the monitor light receiving element 126 is fed back at regular time intervals, and the power-on information of the laser diodes LD1 to LD4 is supplied to the control signals P1 to P4 as shown in FIG. 2. By calculating the result, the control signals P1 to P4 can be grasped.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by the equivalents of the claims of the present invention as well as the claims of the following.

100: optical transmitter
120: multi-channel optical transmission module
140: light output control module
LD1 to LD4: laser diodes
126: monitor receiving element
121 ~ 124: wavelength division multiple filter
125: optical separator
127: collimator
128: optical fiber
LDD1 to LDD4: laser diode drivers
141: transimpedance amplifier
142: automatic power controller

Claims (1)

A plurality of optical signals having different wavelengths output from a plurality of laser diodes are incident to a single optical path through a plurality of wavelength division multiple filters, and a part of the multi-wavelength optical signals combined through the plurality of wavelength division multiple filters is A multi-channel optical transmission module incident to one monitor light receiving element through an optical splitter, and the remaining multi-wavelength optical signal incident on an optical fiber through a collimator; And
An optical output for controlling the driving currents input to the plurality of laser diodes by receiving the remaining multi-wavelength optical signal fed back to the monitor light receiving element in order to stably output the multi-wavelength optical signal in the multi-channel optical transmission module An optical transmitter comprising a control module.

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