KR101741039B1 - Bi-directional optical module - Google Patents

Bi-directional optical module Download PDF

Info

Publication number
KR101741039B1
KR101741039B1 KR1020150099254A KR20150099254A KR101741039B1 KR 101741039 B1 KR101741039 B1 KR 101741039B1 KR 1020150099254 A KR1020150099254 A KR 1020150099254A KR 20150099254 A KR20150099254 A KR 20150099254A KR 101741039 B1 KR101741039 B1 KR 101741039B1
Authority
KR
South Korea
Prior art keywords
optical
optical filter
disposed
light receiving
holder
Prior art date
Application number
KR1020150099254A
Other languages
Korean (ko)
Other versions
KR20170008360A (en
Inventor
신동진
황미희
한세희
Original Assignee
주식회사 오이솔루션
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 주식회사 오이솔루션 filed Critical 주식회사 오이솔루션
Priority to KR1020150099254A priority Critical patent/KR101741039B1/en
Publication of KR20170008360A publication Critical patent/KR20170008360A/en
Application granted granted Critical
Publication of KR101741039B1 publication Critical patent/KR101741039B1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/40—Transceivers
    • H04B10/43—Transceivers using a single component as both light source and receiver, e.g. using a photoemitter as a photoreceiver
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters

Abstract

An embodiment includes a holder including an optical interface; An optical transmitter for outputting a transmission signal; A light receiving unit for receiving a received signal; A first optical filter disposed between the holder and the optical transmission unit, the first optical filter transmitting the transmission signal and reflecting the reception signal; A second optical filter disposed between the first optical filter and the light receiving portion; And a parallel optical lens disposed between the first optical filter and the second optical filter, wherein the holder includes a first coupling portion in which the first optical filter is disposed, and a second coupling portion in which the parallel optical lens is disposed Receiving module.

Description

Bi-directional optical module < RTI ID = 0.0 >

An embodiment relates to an optical transceiver module for use in optical communication.

Generally, an optical transmission / reception module refers to a module in which various optical communication functions are accommodated in one package and connected to an optical fiber. 2. Description of the Related Art In recent years, a bidirectional optical module in which an optical transmitter using a laser diode that can be used for a long distance with a low power consumption as a light source, and an optical receiver that performs optical communication using a photodiode as a module is mainly used.

The bidirectional optical module includes an optical transmitter, an optical receiver, a splitter, and a stub. The transmission signal output from the optical transmitter passes through the splitter and is incident on the stub. The received signal output from the stub is reflected by the splitter and is incident on the optical receiver.

The optical receiver may further include a bandpass filter and a parallel optical lens to filter only the wavelength band of the received signal. According to this structure, since the divergent light is converted into the parallel light by the parallel optical lens, the band pass filter can pass only the wavelength band of the received signal.

However, when the incident angle of light incident on the band-pass filter changes, there is a problem that the transmission band characteristic of the band-pass filter changes and communication sensitivity deteriorates.

The embodiment provides an optical transceiver module capable of maintaining the same transmission band characteristics even when the incident angle of light incident on the band pass filter changes.

The problems to be solved by the technical idea of the present invention are not limited to the above description, but can be more easily understood in the course of describing the specific embodiments of the present invention.

An embodiment of the present invention provides a light emitting device comprising: a holder including an optical interface; An optical transmitter for outputting a transmission signal; A light receiving unit for receiving a received signal; A first optical filter disposed between the holder and the optical transmission unit, the first optical filter transmitting the transmission signal and reflecting the reception signal; A second optical filter disposed between the first optical filter and the light receiving portion; And a parallel optical lens disposed between the first optical filter and the second optical filter, wherein the holder includes a first coupling portion in which the first optical filter is disposed, and a second coupling portion in which the parallel optical lens is disposed Receiving module.

According to an embodiment of the present invention, even when the incident angle of light incident on the band-pass filter changes, the same transmission band characteristic is maintained, and the communication sensitivity is not degraded.

The various and advantageous advantages and effects of the present invention are not limited to the above description, and can be more easily understood in the course of describing a specific embodiment of the present invention.

1 is a diagram illustrating a schematic configuration of an optical T / R module according to an embodiment of the present invention,
FIG. 2 is a view for explaining a process in which light is incident on a light receiving element in an optical T / R module according to an embodiment of the present invention,
3A is a view illustrating a configuration in which a first optical filter and an isolator are mounted on a holder of an optical T / R module according to an embodiment of the present invention,
3B is a view illustrating a configuration in which a second optical filter is mounted on a holder of an optical T / R module according to an embodiment of the present invention,
4 is a view for explaining a state in which an angle of a second optical filter is adjusted according to an incident angle incident on a second optical filter in an optical T / R module according to an embodiment of the present invention,
5 is an enlarged view of a portion A in Fig. 1,
FIG. 6 is a view for explaining the transmission band characteristic in a state where the slope of the second optical filter is adjusted according to the incident angle change,
7 is a view for explaining a transmission band characteristic according to a change in an incident angle in a state where the optical axes of the parallel optical lens and the second optical filter coincide with each other.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present invention, the terms "comprising" or "having ", and the like, specify that the presence of a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

It is to be understood that the drawings are to be construed as illustrative and not restrictive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the drawings, wherein like or corresponding elements are denoted by the same reference numerals, and redundant description thereof will be omitted.

FIG. 1 is a diagram illustrating a schematic configuration of an optical T / R module according to an embodiment of the present invention.

1, the optical T / R module according to the present invention includes a case 100, a holder 310 including an optical interface, an optical transmitter 200 for outputting a transmission signal, a light receiver 200 for receiving a reception signal, A first optical filter 510, a second optical filter 450, and a parallel optical lens 530. The first optical filter 510, the second optical filter 450,

The optical transmission / reception module may be of the SFP (Small Form Factor Pluggable) type, but is not limited thereto and may be various types of optical modules satisfying the MSA (Multiple Source Agreement).

The case 100 is formed with a plurality of insertion holes into which the holder 310, the optical transmission unit 200, and the light reception unit 400 are inserted. The stub 320 inserted into the holder 310 and the optical transmitter 200 are arranged to face each other in the case 100 and the optical receiver 400 is disposed in a direction perpendicular to the direction in which the holder 310 is inserted As shown in FIG. However, the present invention is not limited to this, and the optical transmitter 200 may be disposed in a direction perpendicular to the direction in which the holder 310 is inserted according to the characteristics of the first optical filter 510.

The receptacle 400 is disposed on one side of the case 100. The receptacle 400 includes a holder 310 having an optical interface. More specifically, the optical fiber of the stub 320 may be optically connected to an external optical connector to transmit a transmission signal to the outside or to output a reception signal received from the outside. The other side of the holder 310 may be provided with a connector housing 330 to which the optical connector is coupled. The optical interface may include at least one of a stub and a connector housing.

The optical transmitter 200 transmits a transmission signal to the outside through the stub 320. The transmission signal may be the same as or different from the wavelength of the reception signal output from the optical fiber. The wavelength interval between the transmission signal and the reception signal can be adjusted according to the optical communication system in which the optical T / R module is mounted. The optical transmission unit 200 may be applied to all structures of a general TiO can including a light source 210, a header 220, and a lens 230. And a temperature control unit (TEC) for stabilizing the wavelength of the transmission signal.

The light reception unit 400 converts the reception signal output from the stub 320 into an electrical signal. The light receiving unit 400 includes a light receiving element 410 such as a photodiode. When the optical signal is incident on the photodiode, a reverse current proportional to the incident light amount flows. That is, the light receiving unit 400 can convert an optical signal into an electrical signal by changing the output current according to the amount of incident light.

The isolator 520 blocks optical signals that are reflected by optical fibers or optical components contained within the optical module. Since the received signal normally received from the outside has a wavelength different from that of the transmitted signal, it can be reflected by the first optical filter 510 and transmitted to the optical receiver 400. However, the transmission signal may be reflected by the optical fiber or other optical component, and the reflected transmission signal may be transmitted to the optical transmitter 200 again. Accordingly, the isolator 520 can block the optical signal reflected by the optical fiber or the optical component, thereby removing the reflected noise.

The first optical filter 510 is an optical filter and may be mounted on the holder 310 and disposed between the optical transmitter 200 and the stub 320. The first optical filter 510 can be designed to pass only optical signals of a specific wavelength. For example, the first optical filter 510 may pass the transmitted signal and reflect the received signal.

The second optical filter 450 is a band pass filter that allows only the wavelength band of the received signal to pass through the light reflected by the first optical filter 510. The received signal having passed through the second optical filter 450 is converted into an electric signal by the light receiving element 410.

2 is a view for explaining a process in which light is incident on a light receiving element in an optical T / R module according to an embodiment of the present invention.

Referring to FIG. 2, the received signal emitted from the stub 320 is reflected by the first optical filter 510. At this time, the reception signal includes the main light L11 and divergent light L12 and L13. The main light L11 can be defined as light traveling along the main path (optical axis) of light, and the divergent lights L12 and L13 can be defined as light traveling at a predetermined angle with the main path.

The divergent lights L12 and L13 pass through the parallel optical lens 530 and are converted into parallel light. That is, the main light L11 and the divergent lights L12 and L13 are all converted into parallel light while passing through the parallel optical lens 530. [

The second optical filter 450 may be designed to pass only the wavelength band of the received signal and block the remaining wavelength band based on a predetermined incident angle. Accordingly, the light passing through the parallel optical lens 530 is converted into substantially parallel light, so that the second optical filter 450 passes only the wavelength band of the received signal. Then, the collimated light can be condensed by the condenser lens 440 and transmitted to the light receiving element 410.

If the divergent light L12 or L13 is not converted into parallel light and is incident on the second optical filter 450 with a predetermined slope, the transmission band characteristic of the second optical filter 450 changes, Reflection problems may occur.

FIG. 3A is a view illustrating a configuration in which a first optical filter and an isolator are mounted on a holder of an optical T / R module according to an embodiment of the present invention. FIG. In which the second optical filter is mounted.

3A, the holder 310 may have a cylindrical shape and may include a space 312 through which the isolator 520 is inserted at the front end thereof. The first optical filter 510 may be mounted on the first coupling part 311 inclined toward the space part 312. 3B, a second coupling part 313 on which the parallel optical lens 530 is mounted may be formed on the opposite side of the first coupling part 311. A through hole 314 is formed between the first fastening part 311 and the second fastening part 313 to form a channel through which a received signal passes.

The first optical filter 510 and the parallel optical lens 530 are mounted on the holder 310 so that the parallel optical lens 530 is separately disposed between the holder 310 and the light receiving portion 400 The miniaturization can be made as compared with the configuration. In addition, the first optical filter 510 and the parallel optical lens 530 can be mounted at the correct positions.

4 is a view for explaining a state in which an angle of a second optical filter is adjusted according to an incident angle incident on a second optical filter in an optical T / R module according to an embodiment of the present invention.

4, the ideal received signal L1 output from the stub 320 is reflected by the first optical filter 510, and then is incident on the light receiving element 410. At this time, the reflected reception signal is incident on the second optical filter 450 almost perpendicularly. Here, the concept of divergent light is omitted and the main light is mainly described.

The angle of the light emitted from the stub 320 can be changed by the tolerance of the stub 320 and the holder 310. [ The tolerance between the stub 320 and the holder 310 that may occur in actual production may be +/- 0.5 degrees. Generally, the angle of light emitted from the stub 320 is about 3 degrees to 4 degrees with respect to the optical axis (extension direction of the optical fiber), but an error of +/- 0.5 degrees may occur depending on the coupling tolerance between the stub 320 and the holder 310 have.

The incident angle of the second optical filter 450 may change depending on the changed output angle. That is, when the light output angle changes by? 1, the incident angle of the second optical filter 450 changes by? 3. Here, the incident angle [theta] 3 of the second optical filter 450 is defined as an angle tilted with respect to the normal of the second optical filter 450 (or the central axis of the parallel optical lens).

The transmission wavelength band of the second optical filter 450 may change as the incident angle of the second optical filter 450 changes. Therefore, the received signal L2 can be reflected by the second optical filter 450 and become in a communication disabled state.

For example, in the case of a 100G DWDM system, the channel bandwidth can be allocated to 0.8 nm, and the center wavelength of the transmission signal and the reception signal can be located within 0.8 nm. That is, the wavelength of the received signal and the wavelength of the transmitted signal are allocated very close to each other. Therefore, even if the incident angle of the second optical filter 450 is slightly changed, the received signal can be reflected.

The incident angle 3 of the second optical filter 450 and the error angle 1 of the stub 320 and the holder 310 can satisfy the following relational expression (1).

[Relation 1]

? 3 = a (? 1)

Here, a is a constant satisfying 0.45? A? 0.5.

For example, when the angle of the light emitted from the stub 320 changes by 0.5 degrees from a predetermined angle (about 3 degrees to 4 degrees), the incident angle 3 of the second optical filter 450 actually has an error of 0.23 to 0.25 degrees Lt; / RTI >

Further, even when an error occurs in the second optical filter 450 based on the predetermined reflection angle 2, the incident angle 3 of the second optical filter 450 may change. For example, when the reflection angle 2 of the first optical filter 510 changes by 0.5 degrees from a predetermined angle (e.g., 45 degrees), the change in the incident angle 3 has an error of about 1 degree. Therefore, the incident angle [theta] 3 of the second optical filter 450 can be inclined by a maximum of ± 1.25 degrees.

Therefore, the incident angle 3 of the second optical filter 450, the error angle 1 of the stub 320 and the holder 310, and the error angle 2 'of the first optical filter 510 satisfy the following relational expression 2 Can be satisfied. The error angle 2 'of the first optical filter 510 is an error angle of a predetermined reflection angle.

[Relation 2]

? 3 = a (? 1) + b (? 2 ')

Here, a is a constant satisfying 0.45? A? 0.5 and b is a constant satisfying 0.8? B? 1.2.

According to the embodiment, the second optical filter 450 may be disposed in the light receiving portion 400. Accordingly, the second optical filter 450 can be tilted by the changed incident angle [theta] 3 to adjust the incident angle to be 0 [deg.]. As a result, the second optical filter 450 can maintain the transmission wavelength band as it is.

5, the light receiving portion 400 includes a substrate 420 on which a light receiving element 410 is disposed, and a cover 430 on which the second optical filter 450 is disposed. Specifically, the cover 430 includes a first cover 431 on which the second optical filter 450 is disposed, and a second cover 432 on which the condenser lens 440 is disposed.

The central axis P1 of the light receiving element 410 and the central axis P1 of the second optical filter 450 and the central axis P1 of the condensing lens are arranged to coincide with each other. The center axis P1 of the parallel optical lens 530 is arranged so as to be offset from the center axis P2 of the parallel optical lens 530 by a predetermined angle. Here, the central axes P1 and P2 can be defined as normal lines passing through the center of each object.

According to the present invention, a fixing member 460 may be disposed between the case 100 and the light receiving portion 400. The fixing member 460 is an empty hollow cylindrical member and the light receiving portion 400 is coupled to the inside thereof. At this time, the center axis P2 of the fixing member 460 and the center axis P1 of the light receiving portion 400 are arranged to be shifted from each other. Therefore, the center axis P1 of the second optical filter 450 and the center axis P2 of the parallel optical lens 530 do not coincide.

The angle between the central axis P2 of the fixing member 460 and the central axis P1 of the light receiving portion 400 may be the same as the above-mentioned? 3. The adjustment of the angle? 3 can be performed by first experimentally measuring the error angle, and then tilting the light receiving portion 400 by the changed angle to couple the fixing member 460.

However, the method of tilting the light receiving portion 400 is not necessarily limited thereto. For example, the light receiving portion 400 may be fixed to the case 100 using an adhesive resin. In this case, the light receiving portion 400 can be fixed at a desired angle, and insulation between the case 100 and the light receiving portion 400 can be maintained.

Specifically, the adhesive resin can be cured after the light receiving portion 400 is tilted at a desired angle. The adhesive resin may be an epoxy resin, but is not limited thereto.

FIG. 6 is a view for explaining the transmission band characteristic in a state in which the slope of the second optical filter is adjusted in accordance with the incident angle change. FIG. 7 is a graph showing the transmission band characteristics when the optical axis of the parallel optical lens and the optical axis of the second optical filter coincide with each other. And FIG.

6, when the angle of the light receiving portion 400 is adjusted according to the tilted angle of the reflected light reflected by the second optical filter 450, the transmission band characteristic and the incident angle when the incident angle is 0 degree are 0.75 It can be seen that the transmission band characteristics are the same.

That is, since the second optical filter 450 and the light receiving portion 400 are integrated, it is possible to obtain the effect of canceling the change of the incident angle by adjusting the angle of the light receiving portion 400.

7, when the optical axes of the parallel optical lens 530 and the second optical filter 450 are fixed to coincide with each other, when the incident angle of the second optical filter 450 is inclined by 0.75 degrees, the second optical filter 450 ) Changes in the transmission band characteristic.

For example, when the ideal transmission band characteristic is 1304.5 to 1308 nm, when the incident angle of light incident on the second optical filter 450 is tilted, the transmission band characteristic is shifted to 1306.5 to 1308 nm. Therefore, the reception signal is not received by the light reception unit, resulting in a communication failure.

Particularly, when the transmission signal and the reception signal are allocated in the same channel in order to expand the channel in the CWDM system and the DWDM system, the reception element 410 can not receive the reception signal, resulting in a communication disabled state.

100: Case
200: Optical transmitter
300: Receptacle
400:
410: Light receiving element
450: second optical filter
510: first optical filter
530: Parallel optical lens

Claims (8)

A holder including an optical interface;
An optical transmitter for outputting a transmission signal;
A light receiving unit for receiving a received signal;
A first optical filter disposed between the holder and the optical transmission unit, the first optical filter transmitting the transmission signal and reflecting the reception signal;
A second optical filter disposed between the first optical filter and the light receiving portion; And
And a parallel optical lens disposed between the first optical filter and the second optical filter,
Wherein the holder includes a first coupling portion in which the first optical filter is disposed and a second coupling portion in which the parallel optical lens is disposed,
The light receiving portion includes a substrate on which a light receiving element is disposed, and a cover on which the second optical filter is disposed,
The central axis of the light receiving element and the central axis of the second optical filter coincide with each other,
Wherein the central axis of the second optical filter and the central axis of the parallel optical lens cross at a predetermined angle.
delete The method according to claim 1,
Wherein the cover includes a first cover on which a second optical filter is disposed, and a second cover on which a condensing lens is disposed.
delete The method according to claim 1,
Wherein the holder comprises a stub for outputting a received signal,
Wherein an angle of incidence (? 1) between the stub and the holder and an incident angle (? 3) between the central axis of the second optical filter and the central axis of the parallel optical lens satisfy the following relational expression (1).
[Relation 1]
? 3 = a (? 1)
Here, a is a constant satisfying 0.45? A? 0.5.
The method according to claim 1,
Receiving module including the holder, the optical transmitter, and the optical receiver.
The method according to claim 6,
And the case includes a light absorbing portion disposed on a surface facing the light receiving portion.
The method according to claim 6,
And an adhesive resin for fixing the case and the light receiving portion.
KR1020150099254A 2015-07-13 2015-07-13 Bi-directional optical module KR101741039B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020150099254A KR101741039B1 (en) 2015-07-13 2015-07-13 Bi-directional optical module

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020150099254A KR101741039B1 (en) 2015-07-13 2015-07-13 Bi-directional optical module

Publications (2)

Publication Number Publication Date
KR20170008360A KR20170008360A (en) 2017-01-24
KR101741039B1 true KR101741039B1 (en) 2017-06-01

Family

ID=57993324

Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020150099254A KR101741039B1 (en) 2015-07-13 2015-07-13 Bi-directional optical module

Country Status (1)

Country Link
KR (1) KR101741039B1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20210031949A (en) * 2018-07-23 2021-03-23 후아웨이 테크놀러지 컴퍼니 리미티드 Optical components, optical modules, and communication devices

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102041589B1 (en) * 2018-07-26 2019-11-27 (주)코셋 Apparatus for transmitting and receiving wavelength multiplexing optical signal bidirectionally

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101127633B1 (en) * 2010-12-14 2012-03-22 주식회사 오이솔루션 Bidirectional optical sub assembly having structure to reduce reflection noise
KR101285766B1 (en) * 2012-05-18 2013-07-19 에스케이텔레콤 주식회사 Bidirectional optical transmitting/receiving module

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101127633B1 (en) * 2010-12-14 2012-03-22 주식회사 오이솔루션 Bidirectional optical sub assembly having structure to reduce reflection noise
KR101285766B1 (en) * 2012-05-18 2013-07-19 에스케이텔레콤 주식회사 Bidirectional optical transmitting/receiving module

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20210031949A (en) * 2018-07-23 2021-03-23 후아웨이 테크놀러지 컴퍼니 리미티드 Optical components, optical modules, and communication devices
KR102471480B1 (en) 2018-07-23 2022-11-28 후아웨이 테크놀러지 컴퍼니 리미티드 Optical Components, Optical Modules, and Communication Devices

Also Published As

Publication number Publication date
KR20170008360A (en) 2017-01-24

Similar Documents

Publication Publication Date Title
US9350454B2 (en) Multi-laser transmitter optical subassembly
US8625989B2 (en) Multi-laser transmitter optical subassemblies for optoelectronic modules
US8380075B2 (en) Optical transceiver module
WO2017118271A1 (en) Parallel transmission and reception optical module for dual-link transmission, and preparation method
US20120189323A1 (en) Multi-laser transmitter optical subassembly
WO2014190900A1 (en) Micro bi-directional optical sub-assembly
US7597486B2 (en) Managing backreflection
US9709759B2 (en) NxN parallel optical transceiver
US8995845B2 (en) Multi-laser transmitter optical subassembly for optoelectronic modules
TWI760468B (en) Optical communication module and bidi optical communication module
US9383528B2 (en) Light-receiving module
KR20150138558A (en) Bi-directional optical module
WO2015076469A1 (en) Optical module package structure for narrow wavelength spacing bidirectional communication
KR101741039B1 (en) Bi-directional optical module
KR101723135B1 (en) Bi-directional optical module
US9274294B2 (en) Optical communication module and method for producing the same
KR101115463B1 (en) Bidirectional optical transceiver module
US10921535B1 (en) Optical sub-assembly and telescopic-shaped core cylinder module thereof
US20090279894A1 (en) Triple wavelength bidirectional optical communication system
US20150346432A1 (en) Optical Communication Module
JP2005134803A (en) Ferrule with optical isolator and optical transmission/reception module equipped with the same
US20020191917A1 (en) Transceiver device for transmitting and receiving optical signals
US10811839B1 (en) TO can laser assembly with off-center lens cap and an optical transceiver or transmitter implementing same
EP2078219B1 (en) Managing backreflection
JP2006119464A (en) Single core bidirectional optical transceiver

Legal Events

Date Code Title Description
A201 Request for examination
E902 Notification of reason for refusal
E701 Decision to grant or registration of patent right
GRNT Written decision to grant