AU750467B2 - Optical amplifier with gain adjustment - Google Patents
Optical amplifier with gain adjustment Download PDFInfo
- Publication number
- AU750467B2 AU750467B2 AU10208/99A AU1020899A AU750467B2 AU 750467 B2 AU750467 B2 AU 750467B2 AU 10208/99 A AU10208/99 A AU 10208/99A AU 1020899 A AU1020899 A AU 1020899A AU 750467 B2 AU750467 B2 AU 750467B2
- Authority
- AU
- Australia
- Prior art keywords
- amplifier
- optical
- optical amplifier
- signal
- circulator
- 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.)
- Ceased
Links
- 230000003287 optical effect Effects 0.000 title claims description 40
- 239000000835 fiber Substances 0.000 claims description 18
- 239000004065 semiconductor Substances 0.000 claims description 3
- 230000008878 coupling Effects 0.000 claims description 2
- 238000010168 coupling process Methods 0.000 claims description 2
- 238000005859 coupling reaction Methods 0.000 claims description 2
- 230000005540 biological transmission Effects 0.000 description 7
- 230000010355 oscillation Effects 0.000 description 6
- 230000003321 amplification Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3084—Automatic control in amplifiers having semiconductor devices in receivers or transmitters for electromagnetic waves other than radiowaves, e.g. lightwaves
-
- 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
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
- H01S3/1301—Stabilisation of laser output parameters, e.g. frequency or amplitude in optical amplifiers
- H01S3/1302—Stabilisation of laser output parameters, e.g. frequency or amplitude in optical amplifiers by all-optical means, e.g. gain-clamping
-
- 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
- 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
- H04B10/293—Signal power control
- H04B10/294—Signal power control in a multiwavelength system, e.g. gain equalisation
- H04B10/296—Transient power control, e.g. due to channel add/drop or rapid fluctuations in the input power
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0221—Power control, e.g. to keep the total optical power constant
- H04J14/02216—Power control, e.g. to keep the total optical power constant by gain equalization
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Lasers (AREA)
- Optical Communication System (AREA)
- Semiconductor Lasers (AREA)
Description
GR 97 P 2350 1 Description Optical amplifier with gain control The invention relates to an optical amplifier according to the preamble of patent claim 1.
Digital signals are transmitted using wavelength division multiplexing operation in modern optical transmission systems. This method makes it possible to increase the transmission capacity without having to increase the bit rate in the individual transmission channels. This affords considerable advantages with regard to the delay distortions (dispersion) that occur, and makes it possible to use less complicated transmitter circuits.
Conversions carried out on the transmission system or faults lead to channels being connected up or disconnected. Since the optical amplifiers of a transmission link usually operate in the saturation mode, without additional measures the output levels of the signals transmitted in the active channels would change in the event of channels being disconnected or connected up.
A control circuit which counteracts this effect is described in "Conference on Optical Amplifiers and their Applications", Technical Digest, July 11-13, 1996, Monterey, California, USA; PDP 4-1 to 4-5. A detector measures the output level and controls the pump power.
A further possibility for providing gain control is described on pages FB 2-1 to FB 2-4. This involves clamping of the inversion (amplification) due to laser oscillation. With the aid of fiber gratings serving as reflectors upstream and downstream of an amplifier, a longitudinal resonator is constructed for a wavelength within the transmitted wavelength spectrum. The oscillation build-up of a laser line GR 97 P 2350 2 results given a sufficiently high pump power in the gain being kept constant.
One disadvantage of this solution is that the amplifier has to be transmissive for the laser wavelength in both directions. This condition cannot readily be fulfilled if the amplifier contains optical isolators.
OFC' 97 Technical, pages 130 and 131, discloses an amplifier whose output signal is fed back via a wavelength division demultiplexer, a bandpass filter and an attenuation element being arranged in the feedback path. The signal fed back is fed to the amplifying elements again after having been combined with the input signal via a wavelength division multiplexer.
This circuit requires the use of a plurality of wavelength-dependent components.
A ring resonator is used, therefore, in "Electronics Letters", 28 th March 1991, Vol. 27, No. 7, pages 560 and 561. A fiber coupler taps off part of the output power of the amplifier. With the aid of an optical bandpass filter, a narrow spectral component is selected, attenuated in an attenuation element and fed via a further fiber coupler to the input of the amplifier.
One disadvantage of this amplifier is the occurrence of the wavelength used for the control, the so-called laser line, in the output signal.
The object of the invention is to specify an amplifier having a constant gain in which the laser line is formed only weakly in the output signal.
AAMENDED SHEET 1-
TC
-2a- According to one aspect of the present invention there is provided an optical amplifier configured for gain control, said optical amplifier comprising: at least one amplifier element, wherein a narrowband signal is fed back from an output of said amplifier element, via an attenuation element and a coupling element, to an input of said amplifier element; and an optical circulator and at least one narrowband reflector for reflecting the narrowband signal, said optical circulator and said narrowband reflector being connected in series with the amplifier element to be controlled, wherein the optical circulator has a second output connected to the attenuation element, said second output being adapted to 0o receive said narrowband signal and an input signal.
By means of the invention, interfering effects, such as crosstalk caused by nonlinearities in the transmission fiber and in the receiver, are precluded to a very great extent. The gain is kept constant for all the channels using different wavelengths. The amplifier can, of course, also be used for amplifying just one signal.
In the case of a multistage amplifier, in order to optimize the noise behavior, it is advantageous to insert the coupler for feeding in *g *oo *o o [R:\LIBPP]02431 .doc:iad GR 97 P 2350 3 the laser signal coupled out by the circulator between the first amplifier stage and the amplifier stages to be stabilized.
If different signal bands are intended to be processed, it is expedient to connect two or more fiber gratings downstream of the circulator. The reflection wavelengths of the gratings should be chosen such that each one falls within the passband of a signal band filter. As a result, the laser line reflected by the corresponding fiber grating will build up oscillations.
When a changeover is made to a further signal band filter, the corresponding laser line reflected by another fiber grating will then automatically build up oscillations.
The invention is explained in more detail using two exemplary embodiments.
In the figures, Figure 1 shows a basic circuit diagram of the amplifier according to the invention, and Figure 2 shows a multistage amplifier for different wavelengths.
The basic circuit diagram, illustrated in Figure 1, of a controlled amplifier contains a fiber amplifier or semiconductor laser amplifier as amplifier element V. An optical circulator OZ is connected to the output of said amplifier. The circulator forwards the signal present at a first input to a first output and outputs a signal fed in at said output to a second output. These components can be procured for example from E-TEK DYNAMIKS, INC.
An optical coupler may also be regarded as a special embodiment of the circulator, said optical coupler having a higher degree of attenuation, however.
GR 97 P 2350 4 The output signal of the amplifier is passed from the circulator to the amplifier output A. A reflector FG is incorporated between the output of the optical circulator for the amplifier element output signal and the amplifier output A, which reflector reflects in a very narrow waveband and is realized as a fiber grating or as a dielectric filter.
The reflected narrowband signal having a specific wavelength, the laser line LL, is output via a further output of the optical circulator and is fed back via a variable attenuation element VA and a coupler, realized as a fiber coupler FK in this case, together with the input signal ES, present at the amplifier input E, to the input of the amplifier element V. The signal component, designated as the laser line LL, which is fed back and does not belong to the input signal is generated in the ring resonator and serves alone to control the gain and thus also determines the gain within the wavelength range to be processed, the wavelength range of the input signal ES.
The gain is adjusted by the variable attenuation element. The laser line is practically not present in the output signal AS.
The useful signal and the laser line are illustrated as arrow tips which are filled in and arrow tips which are not filled in.
A fiber amplifier may be used as the amplifier element, in which case a corresponding pump power has to be fed to said fiber amplifier via further couplers, as is disclosed in the prior art described. It is likewise possible to use a semiconductor laser.
Figure 2 shows a two-stage amplifier. If the first amplifier stage Vl operates in the small-signal mode, then it is not necessary to stabilize its gain (amplification). In order to obtain an amplifier which is as free as possible from noise, it is advantageous to insert the coupler FK for feeding in the GR 97 P 2350 5 fed-back signal between the first amplifier stage and the stages to be stabilized, in this case the amplifier stage 2.
Optical bandpass filters are often used, which suppress the transmission of unrequired wavelength ranges, for example components of the amplified spontaneous emission ASE, and only pass signals in the desired wavelength range. If the intention is for the amplifier to be able to process a plurality of signal bands, then a changeover must be made between different filters FII, FI2. As a rule, this also affects the laser line which is used for the control and lies within the signal bands or at the edges thereof.
Therefore, the amplifier illustrated in Figure 2 has a plurality of series-connected reflectors, the fiber gratings FG1 and FG2. The fiber gratings each reflect only one wavelength. In the case of operation with a first signal band filter FII, the laser line LLI reflected by the first fiber grating FG1 will build up oscillations, and the laser line LL2 reflected by the second fiber grating FG2 will automatically build up oscillations when a changeover is made to a second signal band filter FI2. The filters can be arranged at the input and/or output or in the region of the amplifier.
The amplifier was realized for two signal bands in the range of from 1536 nn to 1546 nn and from 1548 nn to 1558 nn. The signal band filters have corresponding pass bands of from 1534 nn to 1547 nn and 1547 nn to 1560 nn. The wavelengths reflected by the two fiber gratings are 1535 nn and 1559 nn. The amplifier was realized for a gain of 25 db with 2 amplifier stages.
It is also possible for a plurality of amplifier stages which are controlled independently of one another to be connected in series.
Claims (12)
1. An optical amplifier configured for gain control, said optical amplifier comprising: at least one amplifier element, wherein a narrowband signal is fed back from an output of said amplifier element, via an attenuation element and a coupling element, to an input of said amplifier element; and an optical circulator and at least one narrowband reflector for reflecting the narrowband signal, said optical circulator and said narrowband reflector being connected in series with the amplifier element to be controlled, wherein the optical circulator has a second output connected to the attenuation element, said second output being adapted to receive said narrowband signal and an input signal.
2. The optical amplifier as claimed in claim 1, wherein said optical amplifier is configured as a ring resonator.
3. The optical amplifier as claimed in claim 1, wherein the circulator is an optical coupler.
4. The optical amplifier as claimed in any one of claims 1 to 3, wherein a plurality of amplifier stages are provided.
The optical amplifier as claimed in claim 4, wherein the narrowband signal is coupled in between said amplifier element to be controlled and any remaining amplifier *e 25 elements.
6. The optical amplifier as claimed in any one of the preceding claims, wherein optical filters are connected into the signal path.
7. The optical amplifier as claimed in claim 6, wherein a plurality of optical reflectors are connected downstream of the circulator.
8. The optical amplifier as claimed in any one of the preceding claims, wherein a T b er grating is provided as the reflector. [R:\LIBPP]02431.doc:iad
9. The optical amplifier as claimed in any one of the preceding claims, wherein a fiber amplifier or a semiconductor amplifier is provided as the amplifier element.
The optical amplifier as claimed in any one of the preceding claims, wherein the attenuation element is adjustable in order to change the giin.
11. The optical amplifier as claimed in any one of the preceding claims, wherein said optical amplifier is provided for wavelength division multiplex signals.
12. An optical amplifier substantially as hereinbefore described with reference to any one of the embodiments as illustrated in Figs. 1 and 2. DATED this twenty eighth Day of May 2002 Siemens Aktiengesellschaft Patent Attorneys for the Applicant SPRUSON FERGUSON .e *o [R:\LIBPP]02431.doc:iad
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19740743A DE19740743C1 (en) | 1997-09-16 | 1997-09-16 | Optical amplifier with gain control |
| DE19740743 | 1997-09-16 | ||
| PCT/DE1998/002539 WO1999014873A1 (en) | 1997-09-16 | 1998-08-27 | Optical amplifier with gain adjustment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU1020899A AU1020899A (en) | 1999-04-05 |
| AU750467B2 true AU750467B2 (en) | 2002-07-18 |
Family
ID=7842550
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU10208/99A Ceased AU750467B2 (en) | 1997-09-16 | 1998-08-27 | Optical amplifier with gain adjustment |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP1016229B1 (en) |
| JP (1) | JP2001517016A (en) |
| CN (1) | CN1332519C (en) |
| AU (1) | AU750467B2 (en) |
| BR (1) | BR9812314A (en) |
| DE (2) | DE19740743C1 (en) |
| HK (1) | HK1031053A1 (en) |
| RU (1) | RU2191478C2 (en) |
| WO (1) | WO1999014873A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101236253B (en) * | 2008-03-07 | 2010-07-07 | 中国科学院上海光学精密机械研究所 | High-precision speed and distance measuring laser radar system and speed and distance measuring method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0497491A2 (en) * | 1991-01-31 | 1992-08-05 | AT&T Corp. | Gain stabilized fiber amplifier |
| EP0707224A1 (en) * | 1994-10-11 | 1996-04-17 | Alcatel N.V. | Wavelength selective optical coupler |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1037735C (en) * | 1993-11-11 | 1998-03-11 | 深圳大学新技术研究中心 | Optical fibre amplifier with dual rasters |
-
1997
- 1997-09-16 DE DE19740743A patent/DE19740743C1/en not_active Expired - Fee Related
-
1998
- 1998-08-27 BR BR9812314-9A patent/BR9812314A/en not_active IP Right Cessation
- 1998-08-27 DE DE59803458T patent/DE59803458D1/en not_active Expired - Lifetime
- 1998-08-27 CN CNB988091917A patent/CN1332519C/en not_active Expired - Fee Related
- 1998-08-27 AU AU10208/99A patent/AU750467B2/en not_active Ceased
- 1998-08-27 WO PCT/DE1998/002539 patent/WO1999014873A1/en active IP Right Grant
- 1998-08-27 RU RU2000109571/09A patent/RU2191478C2/en not_active IP Right Cessation
- 1998-08-27 EP EP98952526A patent/EP1016229B1/en not_active Expired - Lifetime
- 1998-08-27 JP JP2000512298A patent/JP2001517016A/en not_active Withdrawn
-
2001
- 2001-03-12 HK HK01101772A patent/HK1031053A1/en not_active IP Right Cessation
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0497491A2 (en) * | 1991-01-31 | 1992-08-05 | AT&T Corp. | Gain stabilized fiber amplifier |
| EP0707224A1 (en) * | 1994-10-11 | 1996-04-17 | Alcatel N.V. | Wavelength selective optical coupler |
Also Published As
| Publication number | Publication date |
|---|---|
| WO1999014873A1 (en) | 1999-03-25 |
| DE19740743C1 (en) | 1999-01-21 |
| AU1020899A (en) | 1999-04-05 |
| EP1016229B1 (en) | 2002-03-20 |
| HK1031053A1 (en) | 2001-05-25 |
| CN1270719A (en) | 2000-10-18 |
| RU2191478C2 (en) | 2002-10-20 |
| DE59803458D1 (en) | 2002-04-25 |
| BR9812314A (en) | 2000-08-29 |
| CN1332519C (en) | 2007-08-15 |
| EP1016229A1 (en) | 2000-07-05 |
| JP2001517016A (en) | 2001-10-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FGA | Letters patent sealed or granted (standard patent) |