L-band Erbium-doped Fiber Amplifier Research Articles

A dual pumped double-pass L-band EDFA with high gain and low noise

This paper presents an efficient pumping scheme for L-band erbium-doped fiber (EDFA) amplifier to reach high gain and low noise performance in a double-pass configuration. The main L-band amplifier is composed of two sections of EDFs. A 980nm and a 1480nm pump lasers are used to pump the first section of EDF bi-directionally. The generated backward C-band amplified spontaneous emission noise from this EDF is used to pump a subsequent un-pumped section of EDF. In the double-pass scheme, a narrow-band fiber Bragg grating at each channel wavelength is used to back-reflect the L-band signal to make it amplified twice by the pair of EDFs. Compared with its conventional counterpart, this new double-pass configuration provides a lower noise figure and a higher gain. The pump conversion efficiency can be improved by more than 50% in a 3-channel demonstration by using the proposed configuration.

All-optical gain-clamped L-band erbium-doped fiber amplifier with two feedback-loop lasing wavelengths

We experimentally investigate an optically gain-clamped (GC) L-band (1570 to 1600 nm) erbium-doped fiber amplifier (EDFA). Two lasing wavelengths in the optical feedback loop, 1568 and 1600 nm, are separately used for gain clamping with different loop attenuations. The characteristics of the EDFA with single-channel and simulated multichannel operations are examined and compared. We find that the 1568-nm lasing light is a better selection for an L-band GC EDFA to offer good channel gain with satisfactory noise figure characteristics.

장거리 광선로 감시용 1625 nm OTDR 신호 증폭을 위한 효율적인 Extended L-band Erbium-doped Fiber Amplifier

Optical Time Domain Reflectometry를 이용하여 수백 km 이상의 장거리 광통신망을 감시하기 위해서는 감시광을 증폭시켜야한다. 본 논문에서는 1625 nm OTDR 감시광을 증폭시키기 위해 fiber Bragg grating과 band pass filter를 이용하여 이득과 잡음지수를 각각 5.1 dB 그리고 0.9 dB 향상시킨 2단 구조의 Extended L-band EDFA를 제안하였다. 제안된 Extended L-band EDFA의 1625 nm 대역의 신호 이득은 16.3 dB이고 잡음지수는 7.1 dB였다. We have designed an extended L-band Erbium-doped fiber amplifier to amplify 1625 nm optical time domain reflectometry signal for a long distance monitoring system. The proposed amplifier has a dual-stage structure without an isolator. Gain improvement of 5.1 dB has been achieved by adding a fiber Bragg grating and a narrow band pass filter. As a result, the 16.3 dB gain and 7.1 dB noise figure has been successfully accomplished.

Enhancement of pump conversion efficiency in preamplified L-band erbium-doped fiber amplifiers

A new configuration of L-band erbium-doped fiber amplifiers (EDFAs) is presented here. The system contains a double-pass L-band EDFA and an optical preamplifier. Different from conventional preamplified double-pass L-band EDFA systems in which only the forward ASE of the preamplifier is re-used as an auxiliary pump, the new system recycles the backward ASE of the preamplifier as well. Two kinds of main L-band EDFAs are studied, both of which include a section of un-pumped erbium-doped fiber placed in a loop reflector. An improvement of up to 110% in pump conversion efficiency is demonstrated with the proposed recycling of the backward ASE, with respect to the system without recycling.

Signal excited-state absorption in the L-band EDFA: Simulation and measurements

Signal excited-state absorption (ESA) influences the performance of erbium-doped fiber amplifier (EDFA) in the L band. The influence is twofold: 1) ESA is responsible for signal absorption, and thus for noise figure increase in the long wavelength range of the L band and 2) ESA decreases inversion of erbium ions, and as a result, amplifier gain is decreased. Two methods of signal ESA measurement are discussed. It is shown that reliable data can be obtained through measurement and later used for accurate simulation of amplifier performance.

Reduction of temperature-dependent gain in L-band EDFA using antimony-aluminum codoped silica EDF

We report a novel technique to suppress the temperature-dependent gain (TDG) of an L-band erbium-doped fiber amplifier. The composite optical gain block consists of conventional L-band erbium-doped fiber (EDF) serially concatenated with a special EDF in a ternary glass composition, antimony-aluminum codoped silica that showed an opposite TDG coefficient in the L-band. The TDG variation of the composite gain block was suppressed to less than /spl plusmn/1.5 dB for a saturated gain of 15 dB between 1565 and 1605 nm, measured over a temperature range of -40/spl deg/C to +80/spl deg/C.

Gain enhancement in L-band loop EDFA through C-band signal injection

Gain enhancement provided in L-band erbium-doped fiber amplifier (EDFA) with loop configuration and through C-band signal injection is experimentally demonstrated and compared with conventional single-stage L-band EDFA design. Significant backward amplified spontaneous emission suppression in C-band and pump conversion efficiency increase in L-band were observed for varying C-band seed signal wavelength and power levels. Gain and noise figure (NF) performance of loop design L-EDFA is compared with the conventional bidirectionally pumped single-stage L-EDFA design. Gain and NF measurements in the loop configuration have resulted in an up to 9.5-dB increase in gain and up to 2.6-dB degradation in NF at a moderate signal wavelength of 1585 nm.

Hybrid S- to L-band fiber amplifier module with coupled structure

Erbium-doped fiber amplifiers ~EDFAs! with wide bandwidth are considerably interesting for high-capacity transmission in dense wavelength division multiplexing ~DWDM! systems. However, the transmission capacities in DWDM systems are limited by the gain bandwidth of C-band EDFAs ~1530 to 1560 nm!. Furthermore, L-band ~1560 to 1610 nm! fiber amplifier techniques have been achieved, such as EDFAs using a longer erbium-doped fiber ~EDF! than that of C-band EDFAs, fiber Raman amplifiers, or hybrid amplifiers. In addition, a wide-band EDFA from Cto L-band using a coupled structure has also been studied. In other words, two types of wide-band amplifiers with gain bandwidths of around 100 nm have been reported. The first is a coupled-structure amplifier multiplexing the gain bands, namely, the S-band thulium-doped fluoride fiber amplifier ~TDFA! or fiber Raman amplifier and the C-band and L-band erbium-doped fiber amplifiers. The other is a silica-based fiber Raman amplifier ~S-FRA! featuring a multiwavelength pump technique. Recently, a new S-band ~1450 to 1530 nm! amplification technique, which utilizes erbium-doped silica fiber with a depressed cladding design and a 980-nm pump laser to generate EDF gain extension effects, has been

Hybrid three-stage C- plus L-band optical fiber amplifier in cascade configuration

A hybrid C- plus L-band fiber amplifier module with three amplifier stages, which provides an operation range of 1540 to 1600 nm, is proposed and experimentally demonstrated. The proposed amplifier consists of two erbium-doped fiber amplifier (EDFAs) and a semiconductor optical amplifier (SOA) in cascade. Compared with a traditional L-band EDFA having longer EDF length, this amplifier can reduce the total EDF length to 44 m. As a result, 41.5 dB gain and a 3.7-dB noise figure are achieved at 1562 nm over the bandwidth of 1540 to 1600 nm, while the input signal power is –30 dBm. In addition, the behavior and performance of the proposed gain-clamping amplifier module over the C- plus L-band is investigated experimentally under different operation conditions.

Low noise-figure gain-clamped L-band double-pass erbium-doped fiber ring lasing amplifier with an interleaver

A new design of all-optical gain-clamped L-band double-pass (DP) erbium-doped fiber amplifier (EDFA) has been proposed and demonstrated, in which the input port and the odd-channel output port of an interleaver are connected with the DP configuration EDF through a circulator to form lasing ring cavity for clamping gain, and the even port is utilized to export the amplified signals. The low noise figure can be achieved because the lasing power copropagates with the signals, and it is exported separately from the amplified signal thanks to interleaver. Meanwhile, the fiber Bragg grating incorporated in DP configuration suppresses the backward amplified spontaneous emission generation, and therefore improves efficiently the gain and lowers the noise figure. In such a way, the clamped gain of 16.3 dB with a variation below 0.2 dB and noise figure below 5 dB are achieved in the new L-band all-optical gain-clamped EDFA.

Enhancement of Gain in L-Band Bismuth-Based Erbium-Doped FibreAmplifier Using an Un-pumped EDF and Midway Isolator

A hybrid L-band erbium-doped fibre amplifier (EDFA)with enhanced gain characteristic is demonstrated without a significantnoise figure penalty. It uses a backward C-band amplified stimulatedemission from both the ends of a bismuth-based EDFA system to pump anunpumped erbium-doped fibre (EDF) for gain enhancing. The maximum gainenhancement of 4.0 dB is obtained at wavelength 1604 nm with EDF lengthof 20 m. The gain spectrum is reasonably flat in this amplifiercompared with the amplifier without an EDF. The gain varies from27.4 dB to 30.2 dB at wavelength region 1564–1608 nm withincorporation of 20 m EDF. Noise figure also varies from 6.0 to7.7 dB at this wavelength region.

Optimal Design of Optically Gain-Clamped L-band Erbium-Doped Fiber Amplifier by Fiber Bragg Grating Method

We theoretically investigated the optimal design of optically gain-clamped (GC) L-band (1570–1610 nm) erbium-doped fiber amplifier (EDFA), in order to control the EDFA gain to ensure that the gain does not vary markedly in the presence of the add/drop of optical channels. It used a single fiber Bragg grating (FBG) on the input or output end of the erbium-doped fiber (EDF) to inject a portion of the amplified spontaneous emission (ASE) back into the system. The FBG center wavelengths (λB) at either 1565 or 1610 nm for optically gain-clamped operation of such L-band GC-EDFAs were examined. In addition, the different FBG bandwidths (ΔλB) for such L-band GC-EDFAs were compared. From the good gain-clamping capability point of view, the input-end FBG of 1565 nm center wavelength together with 4 nm bandwidth is the best choice for obtaining large gain-clamping dynamic ranges of good channel gain variation (ΔG) and fairly low noise figure characteristics.

Nonsplit dual‐stage EDFA operating in the C‐ plus L‐band

AbstractThe feasibility of a dual‐stage erbium‐doped fiber amplifier (EDFA) design for operation in both the C‐band and the L‐band is studied. The design is comprised of nonsplit single‐pass amplification at both bands, thus eliminating the need for band multiplexing and demultiplexing in an individual band‐amplification design. The results show that the amplifier provides continuous homogeneous gain ranging from 1530 to 1605 nm with an average gain of 19.7 dB at −30‐dBm input signal power. A minimum gain variation of 9.5 dB was achieved for this entire range, which includes the standard 1530‐nm‐region gain peak in a silica‐based EDF and without the assistance of any gain‐flattening devices. The noise figure was below 7.4 dB for the entire C‐ plus L‐band region for a minimum of 5.3 dB at 1570 nm, with signal power of −30 dBm. This C‐ plus L‐band EDFA provides an average output power of 6.1 dBm at −10 dBm input signal power. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 82–84, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20381

120-nm Bandwidth Erbium-Doped Fiber Amplifier in Parallel Configuration

A new S- to L-band erbium-doped fiber amplifier (EDFA) module, which reaches 120-nm gain bandwidth of 1480 to 1600 nm, has been experimentally investigated and demonstrated by using coupled structure. A 32.8-, 34.7-, and 38.1-dB peak gain is obtained at 1504, 1532, and 1568 nm, respectively, when the input signal power is -30 dBm. In addition, this proposed amplifier also provides a broad-band amplified spontaneous emission (ASE) light source of 1480-1606 nm with the output level above -40 dBm.

L-BAND EDFA WITH INJECTION OF C-BAND ASE

The effect of injecting of C-band amplified spontaneous emission (ASE) from C-band erbium-doped fiber amplifier (EDFA) on the performance of L-band EDFA is demonstrated using a circulator and broadband fiber Bragg grating (FBG). Injecting a large amount of ASE (VOA=0 dB) clamps the gain at 15.2 dB from -40 to -10 dBm with a gain variation of less than 0.3 dB. Injecting a small amount of ASE (attenuation of 20 dB and above) improves the small signal gain with a negligible noise figure penalty compared to that of an amplifier without the ASE injection. A maximum gain improvement of 3.5 dB is obtained at an attenuation of 20 dB. These results show that the ASE injection technique can be used either for gain improvement or gain clamping in L-band EDFA.

Structural Detuning of Absorption Rate in Doped Fiber for the Enhancement of Power Efficiency

We propose a novel doped fiber structure, for the enhancement of power conversion efficiency (PCE) in an L-band erbium-doped fiber amplifier. With proper adjustment of the doping profiles for the reduction of pump absorption rate, it becomes possible to optimize the pump evolution inside the doped fiber so as to improve the PCE, while suppressing the development of pump-depleting detrimental amplified spontaneous emission. Exemplary analysis shows significant enhancement in the saturation output power of more than 58.5%, when compared to conventional C-band erbium-doped fiber.

Effective Suppression of Signal-Wavelength Dependent Transients in a Pump-Controlled<tex>$L$</tex>-Band EDFA

Typical pump-controlled L-band erbium-doped fiber amplifiers (EDFAs) in a feed-forward scheme give significant transients due to gain difference on wavelength of input signal when only a few channels are left. The fiber Bragg grating added pump-controlled L-band EDFA eliminates the wavelength dependent gain difference and transients.

Improvement of Gain and Noise Figure in Double-Pass<tex>$L$</tex>-Band EDFA by Incorporating a Fiber Bragg Grating

An obvious improvement on both the gain and noise figure (NF) is demonstrated in the new double-pass L-band erbium-doped fiber amplifier (EDFA) with incorporating a fiber Bragg grating (FBG). Compared with the conventional L-band EDFAs, the gain is improved by about 6 dB in the new configuration for a 1580-nm signal with an input power of -30 dBm at 60 mW of 980-nm pump power. It is important that the NF is greatly reduced in the new configuration, as the FBG greatly compresses the backward amplified spontaneous emission. For the economical utility of pump power and erbium-doped fiber length, such a configuration may be a very competitive candidate in the practical applications of L-band EDFAs.

Demonstration of a highly efficient L‐band erbium‐doped fiber amplifier

AbstractA novel L‐band fiber amplifier comprised of two sections of erbium‐doped fiber (EDF) and an optical reflector is used to enhance power‐conversion efficiency (PCE). We also examine how an optical amplifier can be used without an optical reflector while nonetheless making effective use of amplified spontaneous emission in order to increase the gain. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 96–98, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20059

Use of a genetic algorithm to optimize multistage erbium-doped fiber-amplifier systems with complex structures

We propose optimizing multifunctional multistage erbiumdoped fiber amplifiers (EDFAs) with complex structures by use of a genetic algorithm. With this method, we investigated optimum configurations of C- and L-band gain-flattened multistage EDFAs containing gain-flattening filters and high-loss interstage elements for dense wavelength-division multiplexing systems in detail and compared the amplifiers with various kinds of configurations under different design criteria. With the guidance of optimization results, the roles of all the factors such as pumping schemes, pump-power allocation, component position, and insertion loss in the optimization of EDFAs have been studied, and useful guidelines for optimizations have been provided.