GB2326520A - Erbium doped fibre amplifier - Google Patents
Erbium doped fibre amplifier Download PDFInfo
- Publication number
- GB2326520A GB2326520A GB9818554A GB9818554A GB2326520A GB 2326520 A GB2326520 A GB 2326520A GB 9818554 A GB9818554 A GB 9818554A GB 9818554 A GB9818554 A GB 9818554A GB 2326520 A GB2326520 A GB 2326520A
- Authority
- GB
- United Kingdom
- Prior art keywords
- light signal
- input
- erbium doped
- receiving
- transmitted light
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
Links
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
- H04B10/29—Repeaters
- H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
- H04B10/2912—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form characterised by the medium used for amplification or processing
-
- 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
- H04B10/29—Repeaters
- H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094003—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre
- H01S3/094011—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre with bidirectional pumping, i.e. with injection of the pump light from both two ends of the fibre
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B2210/00—Indexing scheme relating to optical transmission systems
- H04B2210/003—Devices including multiple stages, e.g., multi-stage optical amplifiers or dispersion compensators
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
- Lasers (AREA)
Description
ERBIUM DOPED FIBRE AMPLIFIER
Background to the Invention
The present invention relates to optical communications and, more particularly, to an erbium doped fibre amplifier (EDFA) which uses an excitation light source for amplifying an input light signal.
Conventionally, when an electric signal is converted into a light signal at a transmission stage and sent to an intended place via an optical fibre, that is, a transmission medium, an EDFA is used to amplify the light signal which is weakened at a predetermined distance so as to transmit it as a stable signal. An EDFA is installed at the transmission/reception stage for the purpose of power amplification and pre-amplification.
Referring to FIG. 1 in which a conventional single pumping amplifier is shown, the input connector connects an externally inserted optical fibre to the internal optical fibre of the EDFA. A separation tap 2 separates a light signal input via the optical fibre connected to the input connector and splits the input light signal in a predetermined ratio. The split signals are then input to a photodiode 12 and an optical isolator 4. Here, the photodiode monitors the magnitude of the light signal input. The optical isolator 4 has one input terminal and one output terminal so that it passes the light signal of a predetermined wavelength to the output terminal, and interrupts the light signal returning back from the output terminal to the input terminal. By doing so, the optical isolator 4 interrupts the reverse flow of amplified spontaneous emission (ASE) generated from the erbium doped fibre (EDF) 16 behind it so as to prevent the input light signal from being distorted.
The light signal output from optical isolator 4 is input to wavelength division multiplexer (WDM) 6. The WDM 6 receives two different wavelengths of light signal via two different input ports, and outputs them via one fibre end. Here, the wavelength of the light signal input is 1,550nm, the wavelength of the excitation light source being 980 or 1,480nm.
Via the output terminal of WDM 6, the excitation light source of a wavelength of 980nm and the input light signal of 1,550nm are fed to EDF 16. EDF 16 is made with erbium (element number 68), a rare-earth metal, which has been added to an optical fibre, having a high absorption rate at specific wavelengths such as 800, 980 and 1,480nm. It amplifies the input light signal, having a spectrum which diverges with a bandwidth of about 30nm at a predetermined wavelength (1,550nm).
The output end of EDF 16 is connected to optical isolator 8 which is then connected to tap 10. The tap is connected to the output stage fibre by the output connector. Here, optical isolator 8 interrupts the light signal reflected back from the tap or the connection of the output connector. Tap 10 receives the light signal output from optical isolator 8, and splits it into a light signal output to the fibre connected via the output connector and a light signal for monitoring the output light signal. The monitoring light signal is monitored by photodiode 14.
For a single pumping amplifier, two kinds of method are used which include a forward pumping structure for supplying from a light source an excitation wavelength by
WDM 6 at the front stage of EDF 16, and a reverse pumping structure for supplying from a light source an excitation wavelength via WDM 6 behind the EDF 16. Here, for EDFA, the forward pumping structure uses a pump light of 980nm with high gain and low noise, and is usually utilized for a preamplifier placed just preceding the reception stage in communication means. The reverse pumping structure is mostly used for power amplifiers placed just preceding the transmission stage in the communication means because it amplifies a large signal to increase saturation output, using reverse ASE whose intensity is relatively large compared with forward ASE.
In order to increase the magnitude of output power and gain, the two kinds of single pumping structure are mixed, which is shown in FIG. 2 as a double pumping structure.
However, the double pumping amplifier used to increase output power needs two expensive pump laser diodes, increasing the overall cost of the EDFA. In the case where two pump laser diodes are used at the same time, their service life becomes shorter than when they are used alternately. Furthermore, if they are used in a high-speed transmission network through a conventional EDFA, the gain of transmitted light signal is reduced due to dispersion loss.
Summarv of the Invention
Accordingly, an erbium doped fibre amplifier according to a first aspect of the present invention comprises:
a first erbium doped fibre for receiving an excitation light signal input from a pumping source and reversely amplifying a transmitted light signal received from an input stage;
a first wavelength division multiplexer for receiving and outputting the transmitted light signal from the erbium doped fibre and for receiving the excitation light signal from the pumping source and transmitting it in the reverse direction to the erbium doped fibre; and
a dispersion compensation fibre for receiving the transmitted light signal from the first wavelength division multiplexer and compensating for dispersion losses of the transmitted light signal;
a second wavelength division multiplexer for receiving the transmitted light signal from the dispersion compensation fibre and the excitation light signal from the pumping source at two input terminals and transmitting the two signals to an output terminal; and
a second erbium doped fibre for receiving the excitation light signal and the transmitted light signal from the second wavelength division multiplexer, amplifying the transmitted light signal and supplying the amplified light signal to an output stage.
The amplifier may further comprise an optical coupler for exciting an excitation light signal output from the pumping source at a predetermined rate in two directions and amplifying a transmitted light signal.
The amplifier may further comprise a filter located at an input stage of the dispersion compensation fibre for filtering the transmitted light signal so as to compensate the dispersion of the transmitted light signal having a specific wavelength and outputting only the transmitted light signal having a specific wavelength.
Preferably, there is provided a first optical isolator for receiving the input light signal and supplying it to the first erbium doped fibre; and
a second optical isolator for receiving the amplified light signal from the second erbium doped fibre and supplying it to the output stage.
Preferably, there is provided first and second separation taps for separating a predetermined portion of the light signals from the input stage and the second optical isolator respectively; and
first and second photodiodes for receiving the separated light signal and detecting the magnitude of the transmitted light signal input.
An erbium doped fibre amplifier according to a second aspect of the present invention comprises:
an erbium doped fibre for receiving an excitation light signal input from a pumping source and amplifying a transmitted light signal received from an input stage;
a first wavelength division multiplexer for receiving the input transmitted light signal and the excitation light signal from the pumping source at two input terminals and transmitting the two signals to the erbium doped fibre;
a second wavelength division multiplexer for receiving the transmitted light signal from the erbium doped fibre and outputting it to an output stage and for receiving the excitation light signal from the pumping source and transmitting it in the reverse direction to the erbium doped fibre; and
an optical coupler for receiving the excitation light signal input from the pumping source and outputting it to the first and second wavelength division multiplexers.
Preferably, there is provided a first optical isolator for receiving the input light signal and supplying it to the first wavelength division multiplexer; and
a second optical isolator for receiving the amplified light signal from the second wavelength division multiplexer and supplying it to the output stage.
Preferably, there is provided first and second separation taps for separating a predetermined portion of the light signals from the input stage and the second optical isolator respectively; and
first and second photodiodes for receiving the separated light signal and detecting the magnitude of the transmitted light signal input.
In either aspect of the invention two pumping sources may be provided.
Therefore, an EDFA according to one aspect of the invention is constructed arranged to amplify an input light signal to a high-output light signal using, optionally, a single pump laser diode in a double pumping amplifier structure.
In another aspect, an EDFA is constructed arranged to compensate for the reduction of gain to dispersion loss, which is a problem in high-speed transmission networks, by additionally installing a dispersion compensating optical fibre.
Brief Description of the Drawinqs The present invention will now be described by way of example with reference to the accompanying drawings.
FIG. 1 is a block diagram of a conventional single pumping amplifier.
FIG. 2 is a block diagram of a conventional double pumping amplifier.
FIG. 3 is a block diagram of one embodiment of an EDFA of the present invention.
FIG. 4 is a block diagram of EDFA having dispersion loss compensation fibre according to the present invention.
Detailed DescriPtion of the Preferred Embodiment
Referring to FIG. 3, an input connector connects an externally inserted optical fibre into an internal optical fibre of an EDFA. A separation tap 44 splits a light signal input via the optical fibre connected by the input connector and separates the transmitted light signal input into a predetermined ratio feeding it to a first photodiode 56 and a first optical isolator 46. Here, first photodiode 56 monitors the magnitude of the light signal input. First optical isolator 46 has one input terminal and one output terminal so as to interrupt the reverse flow of amplified spontaneous emission (ASE) generated from the EDF 63 behind it to prevent the light signal input from being distorted.
The transmitted light signal passes through first optical isolator 46 and is input and amplified in amplifier 64.
Amplifier 64 includes a first WDM 48, a second WDM 50, two pump laser diodes 60 and 61, optical coupler 58, and EDF 63. The first WDM 48 receives the transmitted light signal input from first isolator 46, and an excitation light signal separated by optical coupler 58, and outputs these forward via one end of EDF 62. The second WDM 50, receives a separated excitation light source from optical coupler 58, outputting it reversely via the end of EDF 63, and outputs the transmitted light signal finally amplified from the EDF.
EDF 63, located between the first and second WDMs, receives the excitation light signal pumped in two directions via the two multiplexers, amplifies the transmitted light signal, and outputs it to the second WDM. In this particular embodiment, the wavelength of the transmitted light signal input is 1,550nm and the wavelength of the excitation light source is 980 or 1,480nm.
The optical coupler 58 distributes light source pumped from pump laser diodes 60 and 61 to the first and second WDMs in the ratio of, preferably, 50:50, 40:60 or 30:70.
The output end of EDF 63 is connected to optical isolator 52 which is then connected to tap 54. The tap is connected to the output end fibre by the output connector. Here, optical isolator 52 interrupts the light signal reflected back from the tap or the connection of the output connector. Tap 54 receives the light signal output from optical isolator 52, and splits it into a light signal output to the fibre connected via the output connector and a light signal for monitoring the output light signal. The monitoring light signal is monitored by photodiode 62.
In the operation of the EDFA constructed above, the transmitted light signal of 1,550nm input via the input connector is input to optical isolator 46 via separation tap 44. Here, the intensity of the transmitted light signal separated by separation tap 44 is detected by photodiode 56. The transmitted light signal passing optical isolator 46 is input as one input of first WDM 48. The intensity of the light signal of 980 or 1,480nm alternately pumped by two pump laser diodes 60 and 61 is distributed at a predetermined ratio and fed as another input of first WDM 48. The transmitted light signal and excitation light signal input via the two input terminals of first WDM 48 are forwarded and input to the EDF 63 behind it and amplified for a first time. The transmitted light signal is amplified for a second time by the excitation light source input via the second WDM 50 connected behind the EDF, and output to the optical isolator 52 behind the WDM 50 via second WDM 50. Here, the excitation light signal input to second WDM 50 is a signal distributed at a predetermined ratio from optical coupler 58. As a result, the transmitted light signal input to optical isolator 52 is finally output via the output connector. Photodiode 62 connected behind the separation tap 54 detects the intensity of the transmitted light signal amplified and output from the amplifier.
FIG. 4 shows another embodiment of the present invention, namely, an EDFA with a dispersion compensate fibre (DCF).
The transmitted light signal of 1,550nm input via the input connector is input to optical isolator 68 via separation tap 66. Here, the intensity of the transmitted light signal separated by separation tap 66 is detected by photodiode 94. The transmitted light signal passing optical isolator 68 is input to EDF 88. Here, the transmitted light signal (i.e. a light signal output from the pump laser diode 82) is reversely first amplified by the excitation light source input via first WDM 70 connected behind the EDF, and then output to dispersion compensate fibre (DCF) 92 via first
WDM 70. The excitation light signal input to first WDM 70 is a signal that is output from the pump laser diode 82 and is distributed at a predetermined ratio from optical coupler 80. The transmitted light signal input to DCF 92 is compensated for dispersion loss, and then input as one input of second WDM 72. The other input of second wDM 72 is an excitation light signal having been distributed at a predetermined ratio by optical coupler 80. The transmitted light signal and excitation light signal input via the two input terminals of second WDM 72 are forwarded and input to the EDF 90 connected behind it so as to be amplified for a second time and output. The transmitted light signal amplified and output is input to the optical isolator 76, and finally output via the output connector. Here, the photodiode 86 connected to behind separation tap 78 monitors the intensity of the transmitted light signal amplified and output from the amplifier.
As another embodiment of the present invention, the dispersion compensation fibre (DCF) 92 in a single pumping optical amplifier as shown in FIG. 4 further includes a variable filter (not shown) at an output stage, which outputs only transmitted light having a specific wavelength, thus compensating the dispersion characteristics of the transmitted light signal.
As described above, the present invention provides an EDFA structured to amplify a light signal to a high output even with a single pump laser diode in a double pumping amplifier, enhancing output power and allowing for the design of an optical amplifier having the required performance. With a dispersion compensation fibre additionally provided, the reduction of gain by dispersion loss, a problem in high-speed transmission networks, is compensated for.
Claims (9)
1. An erbium doped fibre amplifier comprising:
an erbium doped fibre for receiving an excitation light signal input from a pumping source and amplifying a transmitted light signal received from an input stage;
a first wavelength division multiplexer for receiving the input transmitted light signal and the excitation light signal from the pumping source at two input terminals and transmitting the two signals to the erbium doped fibre;
a second wavelength division multiplexer for receiving the transmitted light signal from the erbium doped fibre and outputting it to an output stage and for receiving the excitation light signal from the pumping source and transmitting it in the reverse direction to the erbium doped fibre; and
an optical coupler for receiving the excitation light signal input from the pumping source and outputting it to the first and second wavelength division multiplexers.
2. An erbium doped fibre amplifier according to claim 1 further comprising:
a first optical isolator for receiving the input light signal and supplying it to the first wavelength division multiplexer; and
a second optical isolator for receiving the amplified light signal from the second wavelength division multiplexer and supplying it to the output stage.
3. An erbium doped fibre amplifier according to claim 2 further comprising:
first and second separation taps for separating a predetermined portion of the light signals from the input stage and the second optical isolator respectively; and
first and second photodiodes for receiving the separated light signal and detecting the magnitude of the transmitted light signal input.
4. An erbium doped fibre amplifier comprising:
a first erbium doped fibre for receiving an excitation light signal input from a pumping source and reversely amplifying a transmitted light signal received from an input stage;
a first wavelength division multiplexer for receiving and outputting the transmitted light signal from the erbium doped fibre and for receiving the excitation light signal from the pumping source and transmitting it in the reverse direction to the erbium doped fibre; and
a dispersion compensation fibre for receiving the transmitted light signal from the first wavelength division multiplexer and compensating for dispersion losses of the transmitted light signal;
a second wavelength division multiplexer for receiving the transmitted light signal from the dispersion compensation fibre and the excitation light signal from the pumping source at two input terminals and transmitting the two signals to an output terminal; and
a second erbium doped fibre for receiving the excitation light signal and the transmitted light signal from the second wavelength division multiplexer, amplifying the transmitted light signal and supplying the amplified light signal to an output stage.
5. An erbium doped fibre amplifier according to claim 4 further comprising an optical coupler for exciting an excitation light signal output from the pumping source at a predetermined rate in two directions and amplifying a transmitted light signal.
6. An erbium doped fibre amplifier according to claim 5 further comprising a filter located at an input stage of the dispersion compensation fibre for filtering the transmitted light signal so as to compensate the dispersion of the transmitted light signal having a specific wavelength and outputting only the transmitted light signal having a specific wavelength.
7. An erbium doped fibre amplifier according to any one of claims 4-6 further comprising:
a first optical isolator for receiving the input light signal and supplying it to the first erbium doped fibre; and
a second optical isolator for receiving the amplified light signal from the second erbium doped fibre and supplying it to the output stage.
8. An erbium doped fibre amplifier according to claim 7 further comprising:
first and second separation taps for separating a predetermined portion of the light signals from the input stage and the second optical isolator respectively; and
first and second photodiodes for receiving the separated light signal and detecting the magnitude of the transmitted light signal input.
9. An erbium doped fibre amplifier substantially as described herein with reference to and/or as illustrated in
FIGs. 3 or 4 of the accompanying drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019960028586A KR980013060A (en) | 1996-07-15 | 1996-07-15 | An optical fiber amplifying device for amplifying transmission light by bi-directionally exciting pump power |
| GB9714810A GB2315361B (en) | 1996-07-15 | 1997-07-15 | Erbium doped fibre amplifier |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9818554D0 GB9818554D0 (en) | 1998-10-21 |
| GB2326520A true GB2326520A (en) | 1998-12-23 |
Family
ID=26311880
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9818554A Withdrawn GB2326520A (en) | 1996-07-15 | 1997-07-15 | Erbium doped fibre amplifier |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2326520A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109462136A (en) * | 2018-12-27 | 2019-03-12 | 无锡市德科立光电子技术有限公司 | A kind of erbium-doped fiber amplifier of adjustable gain |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113992272A (en) * | 2021-10-28 | 2022-01-28 | 北京邮电大学 | A Low Noise Figure Single-Stage Bidirectional Relay System for Optical Fiber Time-Frequency Synchronization |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1994005061A1 (en) * | 1992-08-20 | 1994-03-03 | Bt&D Technologies Ltd. | Multi-stage fibre amplifier |
| EP0621663A1 (en) * | 1993-04-22 | 1994-10-26 | Sumitomo Electric Industries, Limited | Optical fiber amplifier |
| US5457568A (en) * | 1994-11-28 | 1995-10-10 | At&T Corp. | 980 NM pumped erbium fiber amplifier |
| GB2294170A (en) * | 1994-09-26 | 1996-04-17 | Fujitsu Ltd | Optical amplification of wavelength-division-multiplexed signals |
| US5561552A (en) * | 1993-04-13 | 1996-10-01 | Nec Corporation | Optical fiber amplifier unit and method for supplying excited light thereof |
-
1997
- 1997-07-15 GB GB9818554A patent/GB2326520A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1994005061A1 (en) * | 1992-08-20 | 1994-03-03 | Bt&D Technologies Ltd. | Multi-stage fibre amplifier |
| US5561552A (en) * | 1993-04-13 | 1996-10-01 | Nec Corporation | Optical fiber amplifier unit and method for supplying excited light thereof |
| EP0621663A1 (en) * | 1993-04-22 | 1994-10-26 | Sumitomo Electric Industries, Limited | Optical fiber amplifier |
| GB2294170A (en) * | 1994-09-26 | 1996-04-17 | Fujitsu Ltd | Optical amplification of wavelength-division-multiplexed signals |
| US5457568A (en) * | 1994-11-28 | 1995-10-10 | At&T Corp. | 980 NM pumped erbium fiber amplifier |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109462136A (en) * | 2018-12-27 | 2019-03-12 | 无锡市德科立光电子技术有限公司 | A kind of erbium-doped fiber amplifier of adjustable gain |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9818554D0 (en) | 1998-10-21 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3195160B2 (en) | Optical amplifier | |
| US6011645A (en) | EDFA for amplifying transmitted light by dividing an exciting pump power in two directions | |
| JP2000151507A (en) | Optical transmission system | |
| US6867912B2 (en) | Wide-band erbium-doped fiber amplifier and wavelength division multiplexing optical transmission system | |
| EP1073166A2 (en) | L-band optical fiber amplifier using feedback loop | |
| US6823107B2 (en) | Method and device for optical amplification | |
| KR100277352B1 (en) | 3-stage WDM-EDFA | |
| JP3217037B2 (en) | Multi-stage optical fiber amplifier | |
| US6813065B2 (en) | Raman amplifier and optical communication system | |
| KR100810859B1 (en) | Efficient Optical Amplification Gain Enhancement System for Elband Optical Signals | |
| EP1480359B1 (en) | Wideband optical fiber amplifier | |
| US6236777B1 (en) | Reliability of an optical communication system and of an optical amplifying system, and a method suitable to this aim | |
| US6333810B1 (en) | Two-stage erbium doped fiber amplifier using remnant pumping light | |
| EP1418690B1 (en) | Optical amplifying apparatus | |
| KR100396510B1 (en) | Dispersion-compensated optical fiber amplifier | |
| EP1345344A2 (en) | Wide band optical fiber amplifier | |
| US7081989B2 (en) | Wide-band fiber amplifier | |
| KR20040025147A (en) | Wideband optical fiber amplifier | |
| EP1122842B1 (en) | Method for optical direct amplification, and optical amplification repeater and optical transmission system using the same | |
| GB2326520A (en) | Erbium doped fibre amplifier | |
| EP1087550A1 (en) | Method and device for providing optical amplification | |
| CN101232332A (en) | Optical transmission system and signal spectrum correction method | |
| CN101268591A (en) | Raman amplifier structure | |
| EP0878927B1 (en) | Improvement in the reliability of an optical communication system and a method suitable to this aim | |
| EP0930730A2 (en) | An optical repeater |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |