L-band Erbium-doped Fiber Amplifier Research Articles

Weak signal ultrafast interrogation of a micro-nano FBG probe sensor based on the hybrid amplified dispersion Fourier-transform method

To elucidate the thermal transport mechanisms at interfaces in micro- and nanoscale electronic devices, real-time monitoring of temperature variations at the microscopic and nanoscopic levels is crucial. Micro-nano fiber Bragg grating (FBG) sensors have been demonstrated as effective in-situ optical temperature probes for measuring local temperatures. Time-stretch dispersion Fourier transform (TS-DFT) that enables fast, continuous, single-shot measurements in optical sensing has been integrated with a micro-nano FBG probe (FBGP) for local temperature sensing. However, its temperature sensitivity and interrogation resolution are limited by the detection sensitivity. In this paper, we propose a hybrid amplified dispersion Fourier transform (ADFT) method to achieve ultrafast interrogation of FBGP’s weak signal. Thanks to the combined effect of TS-DFT and hybrid optical amplification, the reflection signal of the FBGP is amplified, and the wavelength shift of the FBGP sensor is converted to a temporal spacing change between two dispersed pulses through dispersion-induced wavelength-to-time mapping. The proposed method uses a homemade dissipative soliton mode-locked laser as the light source. The hybrid optical amplification technique comprises a L-band erbium-doped fiber amplifier and a distributed Raman amplifier. Their noise figure and net gain for the FBGP are 4.81 dB and 15.93 dB, respectively. In addition, the temperature calibration experiments show that a sampling rate of 51.43 MHz and the maximum temperature measurement error of 1.98°C are achieved within the temperature range of 20.3°C to 97°C. The stability of the net gain provided by the hybrid ADFT system is demonstrated by the coefficient of variation, which ranges from 2.22% to 2.95% in the peak voltage signal of the FBGP. This approach applies to scenarios requiring the handling of weak optical signals, particularly in temperature measurement at the micro-nano scale.

Analysis of signal excited-state absorption for improving extended L-band erbium-doped fibers.

The precise characterization of signal excited-state absorption (ESA) in erbium-doped fibers (EDFs) is achieved through an ON/OFF pumping scheme, using a supercontinuum source in conjunction with a bandpass tunable filter to generate the input signal. Normalizing the ESA profile, by the value of the ESA peak, allows sample comparisons independent of their erbium concentration. This method directly assesses the impact of ESA on the net gain within the 1600-1730 nm range, providing a significant means to study how to expand the gain bandwidth toward longer wavelengths. As an illustrative application, we investigate the effect of chemical elements, such as Er, Al, and Ba, and their concentrations on ESA. We then optimize the Al content to enhance erbium solubility without inadvertently inducing detrimental ESA effects. This advancement in the ESA characterization presents substantial advantages for the pursuit of efficient extended L-band erbium-doped fiber amplifiers (EDFAs).

Tunable gain clamping L-band erbium-doped fiber amplifier based on FBG and BBM

An improved structure for the L-band Erbium-doped fiber amplifier (EDFA) with gain clamping is suggested to address gain instability resulting from variations in the number of optical channels and the compromised gain clamping performance due to misalignment in the center wavelength of the grating. Here, a linear resonant cavity is formed by a broad-band mirror (BBM) and fiber Bragg grating (FBG), and a variable optical attenuator (VOA) is used for cavity loss adjustment. Experimental results show that the L-band EDFA solves the problem that the center wavelength of the narrowband grating pairs needs to be consistent. The 20 dB gain bandwidth is 42 nm(1582 ∼ 1623 nm). For signal at 1605 nm, the gain can be tuned from 28.8 to 34.8 dB, and a 40 dB (−50 to −10 dBm) gain clamped dynamic range is obtained at the gain of 28.8 dB, with stability of ± 0.25 dB, for which noise figure (NF) is less than 5.3 dB.

Multi-pulse random fiber laser with wide tuning range in L-band based on tunable band-pass filter and electro-optic modulator

In this paper, a L-band random fiber laser (RFL) with wide tuning range based on tunable band-pass filter (TBF) and electro-optic modulator (EOM) is proposed and studied. The L-band erbium-doped fiber amplifier (L-EDFA) is added to output L-band laser, and a wavelength tunable band-pass filter is used to generate tunable wavelength output. When the pump power is increased from 50mW to 350mW, the output spectra are all chaotic multi-wavelengths. After the filter being added, a stable narrow-band single-wavelength laser can be output in the range of 1564–1618 nm. An EOM is added to introduce actively Q-switched. When the pump power is 50mW, a stable single pulse output can be observed on the oscilloscope. When the pump power is 100mW, the output pulse is double pulse. When the pump power exceeds 100mW, three pulses or four pulses phenomenon appears. The adjustable multi-pulse laser has a wide application prospect in pulse coding, secure communication and other fields.

Dual-Stage Double-Pass Extended L-Band Erbium-Doped Fiber Amplifier with Improved Gain Performance

Extended L-band erbium-doped fiber amplifiers (EDFAs) have attracted much attention in recent years despite their relatively low gain levels. In this paper, a dual-stage extended L-band EDFA with improved gain level is demonstrated by using an Er/Yb/P co-doped fiber-based double-pass structure assisted by a low noise pre-amplifier. High gain levels of up to 48.79 dB at 1566 nm and 20.05 dB at 1621.4 nm are achieved with saturated output power at 1605 nm of 20.58 dBm under a total pump power of only 400 mW. Bandwidths with the gain of more than 20 and 30 dB are reached up to 66 nm (1555.4–1621.4 nm) and 58.4 nm (1557.5–1615.9 nm), respectively. The noise figure benefited by using the low noise pre-amplifier is 5.40 ± 1.55 dB in the 1565–1610 nm range. The wide gain bandwidth, high gain level and relatively low pump power give it great potential for future high-capacity optical fiber communication systems.

Flat-gain L-band amplifier containing AlPO4 units in aluminophosphosilicate erbium-doped fibers.

We present a flat-gain single-stage L-band erbium-doped fiber amplifier (EDFA) with a gain ripple of ±0.7 dB from 1580 to 1615 nm, by using aluminophosphosilicate erbium-doped fiber (APS-EDF) with an estimated AlPO4 composition of 13.3 mol%. A series of APS-EDFs were fabricated with increasing AlPO4 and Er concentrations, while maintaining a low background loss of 0.031 ± 0.005 dB/m and preventing Er ion clustering. The spectroscopic study shows a slightly narrowing Er cross section and flattened emission cross-section spectrum in the L-band with more AlPO4, thus favoring the L-band amplification with an improved gain flatness. Also, the gain coefficient, gain saturation, and temperature-dependent gain characteristics were reported. A better temperature tolerance was observed with increasing AlPO4.

Extended L-Band Erbium-Doped Fiber Amplifier with High Gain Using Two-Stage Double-Pass Configuration

Extended L-Band Erbium-Doped Fiber Amplifier with High Gain Using Two-Stage Double-Pass Configuration

Wide and stabilized erbium laser with single-mode and kHz linewidth output

In the work, to reach the broad tunability, narrow linewidth and stable single-longitudinal-mode (SLM) output of erbium-doped fiber (EDF) based laser, the dual-ring configuration with a unpumped EDF saturable absorber (SA) is designed. Here, the C- and l-band erbium-doped fiber amplifiers (EDFAs) are used in parallel acting as gain medium inside the laser cavity to increase the available bandwidth for tuning wavelength. Moreover, the achieved output power, wavelength linewidth, optical signal to noise ratio (OSNR), tunability and stability of the proposed EDF laser are also executed and discussed.

Gain and Noise Figure Analysis of Erbium Doped Fiber Amplifier Based on Double Pass Configuration Using Forward Pumping

In this paper, gain and noise figure of Erbium Doped Fiber Amplifier (EDFA) is analyzed based on double pass with Wave Selective Coupler (WSC). The main contribution in this study the use of a (WSC) to eliminate the residual pump power out of the signal and attain optimal result in L-band. This method decreases the self-saturation effect of ASE. Also, the study shows the effect on input and output signal power in L-band Erbium Doped Fiber Amplifiers with pump power using forward pumping. Moreover, the researchers analyzed the high-yield behavior and characterization details of the new double-pass EDFA with WSC. Finally, the study shows the effects of pump power on gain and noise figure with input and output signal power in L-band at 1590 nm.

Investigation of Bi-Directionally, Dual-Wavelength Pumped Extended L-Band EDFAs

We present numerical and experimental analysis of bi-directionally, dual-wavelength pumped extended L-band erbium-doped fiber amplifiers (EDFAs) that use a standard 1480 nm laser diode as the forward pump source and a high-power C-band light source as the backward pump source. When using a ~1535 nm backward pump, efficient amplification can be obtained over the extended L-band with no penalty to the noise figure. Experimentally, a bi-directionally pumped L-band EDFA achieves a wideband 20 dB-gain, covering 1570–1619 nm, with a noise figure lower than 5.6 dB. With either 1530.7 nm or 1537.8 nm as the backward pump wavelength, and 1480 nm as the forward pump wavelength, the power conversion efficiency is 40% higher compared to a configuration using 1480 nm pumping for both directions. To our best knowledge, it is the first time that C-band light has been used as the backward pump source for extended bandwidth of L-band EDFAs operating beyond 1610 nm.

Investigation of C-band pumping for extended L-band EDFAs

In this study, we present systematic numerical and experimental analysis of high-power C-band light pumping in extended L-band erbium-doped fiber amplifiers (EDFAs). We investigate, for the first time to the best of our knowledge, how C-band light sources can be used as pump sources to extend the bandwidth of L-band EDFAs beyond 1610 nm. Results show that, when using a C-band light source as the sole pump, efficient amplification is obtained over the extended L-band, but at the expense of a higher noise figure. However, the advantage of C-band pumping in terms of power conversion efficiency can be exploited when using a two-stage EDFA, with a first stage pumped by 1480 nm to maintain good noise figure performance and a high-power C-band light source (up to several hundred mW) as the pump source for the second stage. Thus, a 20 dB gain covering 1570–1618 nm with a maximum noise figure of 5.7 dB is demonstrated.

Double pass remotely pumped L-band EDFA with the integration of Raman amplification using multiwavelength dispersion compensator

We demonstrate a remotely pumped L-band erbium-doped fiber amplifier for long-haul transmission system that consists of a multiwavelength dispersion compensator. In this proposed amplifier, the L-band signals experience double pass amplification using the multiwavelength dispersion compensator as signal reflector. In addition, the distributed Raman amplification helps to improve the gain flatness of the propagated signals that is pumped by a 1497 nm fiber laser. High average transmission gain of 20.64 dB with low gain flatness of 2.64 dB is attained when the input signal power is at 0 dB m with wavelength ranging from 1570.45 to 1604.92 nm. The proposed amplifier structure offers better transmission gain flatness for multiwavelength systems.

Stability improvement in a gain-clamped L-band erbium-doped fiber amplifier through hybrid gain control

The stability of gain-clamped erbium-doped fiber amplifiers (EDFAs) may be affected by the parameter drift of active and passive devices. We propose a hybrid gain-control scheme to enhance the working stability, which consists of an optical dual-fiber-Bragg-grating (FBG)-based linear cavity and an electrical fuzzy-based controller. The principle of optical gain clamping is then depicted and a detailed design about dual-channel fuzzy controller is given. The experimental results show that, in the dual-FBG configuration, with 20.2-dB mean gain, the designed L-band EDFA simultaneously guarantees the ±0.1-dB stability (with 30-dB dynamic range) and the ∼0.4-dB flatness in the range of 1570 to 1610 nm. In addition, under the electrical feedback control, the flatness stability of gain spectrum reaches ±0.18 dB within 60 min and the mean gain stability is about ±0.34 dB within 10-h continuous operation.

The effect of ASE reinjection configuration through FBGs on the gain and noise figure performance of L-Band EDFA

In this study, we present the gain and noise figure performance improvement in L-band erbium-doped fiber amplifier (L-EDFA) provided by amplified spontaneous emission (ASE) reinjection through different configurations of 1533nm band FBGs. The experimental results are compared with a single-stage bidirectionally pumped conventional L-EDFA design. It is shown that when the forward and/or the backward ASE noise is partly reinjected to L-EDFA using a double/single 1533nm fiber Bragg gratings (FBG), the gain and noise figure performance of L-EDFA increases depending on the FBG configuration. The best gain and NF performance in our L-EDFA was achieved by reinjection of forward and backward ASE through FBG1 and FBG2 leading to an 4.5dB increase in gain and 1dB decrease in NF at 1585nm and −30dBm input signal power. The results show that both FBGs must be used at the same time to improve gain and NF performance in L-band EDFAs.

Four-fold increase in users of time-wavelength division multiplexing (TWDM) passive optical network (PON) by delayed optical amplitude modulation (AM) upstream

Abstract In this paper, we have proposed and simulated optical time division multiplexed passive optical network (TDM-PON) using delayed optical amplitude modulation (AM). Eight upstream wavelengths are demonstrated to show optical time wavelength division multiplexed (TWDM) by combining optical network units (ONU) users data at the remote node (RN). Each ONU generates 2.5 Gb/s user data, and it is modulated using novel return to zero (RZ) delayed AM. Optical TDM aggregates 10 Gb/s data per wavelength from four 2.5 Gb/s upstream user data, which facilitates four different ONU data on the same wavelength as 10 Gb/s per upstream wavelength and, simplify the laser requirements (2.5 Gb/s) at each optical network unit (ONU) transmitter. Upstream optical TWDM-PON is investigated for eight wavelengths with wavelength spacing of 100 GHz. Novel optical TDM for upstream increased the number of the simultaneous user to fourfold from conventional TWDM-PON using delayed AM with a high-quality-factor of received signal. Despite performance degradation due to different fiber reach and dispersion compensation technique, Optical TWDM link shows significant improvement regarding receiver sensitivity when compared with common TWDM link. Hence, it offers optimistic thinking to show optical TDM at this phase as one of the future direction, where complex digital signal processing (DSP) and coherent optical communication are frequently demonstrated to serve the access network. Downstream side conventional TWDM eight wavelengths are multiplexed at the OLT and sent downstream to serve distributed tunable ONU receivers through an optical distribution network (ODN). Each downstream wavelengths are modulated at the peak rate of 10 Gb/s using non-return to zero external modulation (NRZ-EM). The proposed architecture is cost efficient and supports high data rates as well as “pay as you grow” network for both service providers and the users perspectives. Users are classified into two categories viz home-user and business-user, with an option for easy up-gradation. Proposed architecture operates on next generation passive optical network stage 2 (NG-PON2) wavelength plan, with symmetrical data rate. Downstream performance is investigated by comparing, high power laser source with a conventional laser source and the L-band Erbium-doped fiber amplifier (EDFA) of gain 10 dB and 20 dB. Downstream eight wavelengths perform error-free up to 40 Km fiber reach and 1024 splitting points. Power budget of the proposed architecture incorporates the N1, N2, E1 and E2 optical path loss class.

Bidirectional EDFAs That Support E2-Class Power Budget of TWDM-PON Without Using Gain-Clamped Light Source

This paper introduces an Erbium-doped fiber amplifier (EDFA)-based solution to support the maximum link budget class (E2) of the time- and wavelength-division multiplexed passive optical network (TWDM-PON). Bidirectional EDFAs, each consisting of an L-band EDFA as the downstream WDM signal booster and a C-band EDFA as the upstream WDM signal preamplifier, are utilized to reduce the number of EDFAs required. Technical challenges are how to widen the input dynamic range of upstream burst signal detection using a preamplifier, and how to reduce the number of optical components. To resolve these issues, a novel device configuration is proposed, where a very short C-band EDF is pumped by a high-power pump light and the pump power unused by the C-band EDF is reused to pump the L-band EDF. A prototype integrated in an MSA-size package is developed, and its effectiveness in supporting the E2-class power budget is experimentally confirmed.

Wavelength control of erbium-doped fiber ring lasers by means of π-shifted variable long-period fiber gratings

In this paper, fiber ring resonators are composed of an erbium-doped fiber amplifier (EDFA) with a π-shifted long-period fiber grating (PS-LPFG) to control the lasing wavelength. The PS-LPFG forms the passband inside the rejection band in the transmission spectrum, and the passband is shifted to longer wavelengths by stretching a coil spring that presses the fiber with an electromagnet. The oscillation wavelength is shifted from 1532.8 to 1565.1 nm depending on the variable grating period by using the C-band EDFA. By replacing to the L-band EDFA, the tunable wavelength range is moved to the range from 1586.8 to 1613.8 nm. The laser emission spectra exhibit the 3 dB spectral bandwidth of ~0.1 nm with a side-mode suppression ratio of ~40 dB.

Optimization with genetic algorithm of temperature-dependent fiber length of L-band EDFA gain

Erbium-doped fiber amplifiers (EDFAs) have great importance in long-distance communication. It is required to have equal gain for all signals that are transferred and to avoid loss in the receiver of long-distance communication systems. However, temperature dependence changes the output spectrum of the designed gain-flattening systems. In this study, each erbium-doped fiber (EDF) length of a two-stage L-band EDFA has been optimized using a genetic algorithm method; because of the temperature dependence of EDFAs, there is no general rule. Thus, a simple, fast, dynamic, and highly accurate model has been developed and obtained for different EDF lengths that will fix gain along the L-band. The results have been shown to be very compatible with the previously obtained numerical values.

Accurately control and flatten gain spectrum of L-band erbium doped fiber amplifier based on suitable gain-clamping

The increasing traffic with dynamic nature requires the applications of gain-clamped L-band erbium-doped fiber amplifier (EDFA). However, the weak or over clamping may lead the unexpected gain-compression and flatness-worsening. In this article, to enhance practicality, we modify the partly gain-clamping configuration and utilize a pair of C-band fiber Bragg gratings (FBGs) to non-uniformly compress the gain spectrum of L-band. Through a comprehensive test and comparison, the suitable gain-clamping region for the amplified signals is found, and the gain in L-band is accurately controlled and flattened under the matched central wavelength of FBGs. The experimental results show that, our designed L-band EDFA achieves a trade-off among the output gain, flatness and stability. The ±0.44dB flatness and 20.2dB average gain are together obtained in the range of 1570–1610nm, with the ±0.1dB stability of signals in over 30dBm dynamic range.

Ultrawide broadband photonic source based on a new design of mode-locked erbium-doped fibre laser

Pulses with a spectral width of 134 nm at −6 dBm nm−1 and 223 nm at −20 dBm nm−1, covering L-band and U-band and longer wavelengths (even beyond 1700 nm), are achieved by means of a new design of passive mode-locked erbium-doped fibre laser. This source includes a C/L-band filter inside a ring cavity with an L-band erbium-doped fibre amplifier as active medium and its output pulses are amplified by means of a second L-band amplifier. It is demonstrated that output spectra are clearly broadened due to the presence of the C/L band filter.