Noise Figure Spectra Research Articles

Theoretical study on ultra-broadband gain and low noise characteristics of PbS quantum dots-doped silica fiber amplifier

To study the performance of the PbS quantum dots (QDs)-doped silica fiber amplifier (PQDFA), here, a model of PQDFA with ultra-broadband gain and low noise is theoretically proposed. Based on this model, the impact of fiber structure, pump/signal power, and PbS QDs properties on the noise figure (NF) of PQDFA is investigated. The simulation results show that pump/signal light power changes the NF of PQDFA by affecting the population inversion level. Besides, the Stokes-shift and doping concentration proportion of QDs also affect the performance of fiber amplifiers. In addition, the gain and NF spectrum of single- and multi-sized PQDFA are simulated and compared. The simulation results show that the working band of PQDFA is determined by the QDs’ emission spectra, and wavelength tunability can be achieved by changing the QDs’ distribution in fiber. For the multi-sized PQDFA proposed in this paper, under −10 dBm input signal power, the 3 dB bandwidth, highest gain, and lowest NF in 1300–1500 nm band are 107 nm, 29 dB, and 3.84 dB, respectively.

Quantum noise spectrum in fiber-based nondegenerate phase-sensitive amplification considering phase mismatch and Raman scattering

Wavelength dependence of quantum noise in nondegenerate phase-sensitive amplification in an optical fiber, where signal and its phase-conjugated idler lights are incident into a fiber together with pump light, is theoretically investigated. An analytical formula of the quantum-limited noise figure, that takes Raman scattering into account as well as parametric amplification, is derived based on full quantum mechanical treatment. Using the obtained formula, a calculation example of the noise figure spectrum is also presented, where the pump light phase is adjusted so that the signal gain is maximum at a phase-matched wavelength, supposing multichannel amplification.

Gain and Noise Figure Characteristic of EDFA by Four Stage Method

loss is a fundamental limitation in realizing long haul point-to-point fiber optical communication links and optical networks. One of the advanced technologies achieved in recent years is the advent of erbium doped fiber amplifiers (EDFAs) that has enabled the optical signals in an optical fiber to be amplified directly in high bit rate systems beyond Terabits. In this paper, an EDFA simulation program has been written in opt system to characterize Gain, Noise Figure and optical signal to noise ratio (OSNR). The four stage enhancement circuit has been designed and simulation studies for different types of pump power. Further, for the EDFA with comparatively better gain and noise figure spectrum, the pump powers are varied and a comparison of gain and noise figure with respect to wavelength is carried out.

Design and Performance Investigation of a New Distributed Amplifier Architecture for 40 and 100 Gb/s Optical Receivers

The design of distributed amplifiers (DAs) is one of the challenging aspects in emerging ultra high bit rate optical communication systems. This is especially important when implementation in submicron silicon complementary metal oxide semiconductor (CMOS) process is considered. This work presents a novel design scheme for DAs suitable for frontend amplification in 40 and 100 Gb/s optical receivers. The goal is to achieve high flat gain and low noise figure (NF) over the ultra wideband operating bandwidth (BW). The design scheme combines shifted second tire (SST) matrix configuration with cascode amplification cell configuration and uses m-derived technique. Performance investigation of the proposed DA architecture is carried out and the results are compared with that of other DA architectures reported in the literature. The investigation covers the gain and NF spectra when the DAs are implemented in 180, 130, 90, 65 and 45 CMOS standards.The simulation results reveal that the proposed DA architecture offers the highest gain with highest degree of flatness and low NF when compared with other DA configurations. Gain-BW products of 42772 and 21137 GHz are achieved when the amplifier is designed for 40 and 100 Gb/s operation, respectively, using 45 nm CMOS standard. Thesimulation is performed using AWR Microwave Office (version 10).

Measurement of the Internal Loss Coefficient of Semiconductor Optical Amplifiers

The internal optical loss in semiconductor optical amplifiers (SOAs) is investigated experimentally and theoretically over a wide injection current range. A new measurement method is proposed without noise figure spectra. Theoretically, considering the internal loss in an SOA, a modified formula of the input-output characteristics is deduced. Based on the practically measured input-output characteristic curves, the internal loss coefficient of an SOA is measured at different injection currents. The results demonstrate that the internal loss coefficient of SOAs decreases with increasing injection current.

Experimental analysis of internal optical losses in polarization-insensitive semiconductor optical amplifiers

We experimentally investigated the internal optical loss of a polarization-insensitive multiple quantum well semiconductor optical amplifier (SOA) over a wide injection current range. The precise fitting of noise figure spectra using gain spectra and transparent wavelengths enabled a direct estimation of internal optical loss inside gain bandwidth. The internal optical loss of the SOA exhibited large dependencies on injection current and the optical confinement factor of the active layer. A large difference in optical losses between polarization modes and operating wavelengths of the SOA indicates a strong influence of intervalence band absorption.

Full characterization of the signal and idler noise figure spectra in single-pumped fiber optical parametric amplifiers

For the first time, four different noise sources, which are amplified quantum noise, Raman phonon seeded excess noise, pump transferred noise (PTN), and pump residual noise, are considered simultaneously to model the wavelength-dependent noise figure in a single-pumped fiber optical parametric amplifier. An asymmetric signal NF spectrum induced by both Raman phonon seeded excess noise and Raman gain modified PTN is measured in the electrical domain. Theoretical results agree very well with the experimental data. The idler NF spectrum is also analyzed and measured, which shows a more symmetric profile.

Gain and noise figure spectrum control algorithm for fiber Raman amplifiers

In this letter, a fiber Raman amplifier (FRA) design method enabling the simultaneous control of the gain and noise figure (NF) spectra, is proposed. By constructing the FRA with predetermined target forward/backward gain spectra, the spectral error function of NF is calculated, to determine the pump power combination satisfying both the targeting gain and NF spectra. The FRA gain/NF design within 0.1 dB of accuracy is demonstrated for various shapes of target spectra.

Design and spectral characteristics of gain-flattened tellurite-based fiber Raman amplifiers

The design and the spectral gain and noise figure (NF) characteristics of tellurite-based fiber Raman amplifiers (FRAs), which are tellurite FRAs (T-FRAs) or hybrid tellurite/silica FRAs (hybrid FRAs), are described. Propagation equations for a multiwavelength (multi-/spl lambda/)-pumped T-FRA that include the pump interaction terms are presented, with which the gain and NF of the T-FRA can be calculated. Tellurite fiber (TF) length dependences of gain and NF of a T-FRA are clarified experimentally and theoretically. Numerical calculations on the gain and NF spectra of the tellurite-based FRAs show that a T-FRA with a two-stage configuration and a hybrid FRA with a three-stage configuration can provide seamless gain bands with widths of more than 130 nm over the S-, C-, and L-bands. The two-stage T-FRA has a couple of two-/spl lambda/-pumped T-FRA stages, and a gain equalizer (GEQ) and a dispersion-compensation fiber (DCF) between the T-FRA stages, while the three-stage hybrid FRA has a couple of two-/spl lambda/-pumped T-FRA stages, and a GEQ and a two-/spl lambda/-pumped DCF Raman amplifier (DCF-RA) stage between the T-FRA stages. The numerical calculations also show that the two-stage T-FRA and the three-stage hybrid FRA achieve top gains with regard to their flattened gain spectra of 9.7 and 24 dB, and maximum NFs in their gain bands of 11.8 and 8.2 dB, respectively. Measured gain and NF spectra of the tellurite-based FRAs coincide well with the corresponding calculated spectra.

A Novel Bi-wavelength Method for Accurately Measuring Gain andNoise Characteristics of an Erbium-Doped Fibre Amplifier forMulti-Channel Wavelength Division Multiplexing Transmission

Gain and noise figure (NF) are the most important two parameters of anerbium-doped fibre amplifier (EDFA) for a multi-channel wavelengthdivision multiplexing (WDM) transmission system. A simple bi-wavelengthmethod for accurate gain and NF spectrum measurement of EDFA for WDMapplications is proposed. A saturating input signal, whose power equalsto the sum of all the WDM signal power and whose wavelength isdetermined by the channel numbers, and the wavelength of the WDM inputsignals saturates the EDFA in a degree as the same as the WDM signalsinput. Meanwhile, a small power probe signal scans and measures thegain and the NF value at every wavelength of the WDM input signals.Investigative results by numerical simulation show that the gain andthe NF spectra measured by this method have good agreement with thereal spectra of the WDM signal input in a large total input powerrange. The maximum errors of the gain and the NF are less than 0.2 dBand 0.16 dB, respectively, for a 50-channel input case. The method iscompetent for the accurate gain and the NF spectrum measurement of thefibre preamplifier and the line-amplifier for WDM applications and hasthe advantages of simplicity, convenience and easy implement.

Pump Power Dependent black Box EDFA Model

An explicit pump and signal power dependent black box model for the erbium doped fiber amplifier (EDFA) is presented. The model predicts the EDFA spectral gain and noise figure under arbitrary pump and saturating conditions. The prediction is based on only two measured reference spectra for the gain and two for the noise figure. Calculated gain and noise figure spectra show excellent agreement with experiments to within 0.5 dB for 1535 nm < λ < 1575 nm for two amplifiers with and without 1530 nm amplified spontaneous emission (ASE) noise filtering. The amplifier with 1530 nm filtering even displays agreement to within 0.8 dB for 1525 nm < λ < 1575 nm.

Gain and noise characterisation of erbium doped fibre amplifiers

A technique for computer-controlled measurement of the gain and noise figure spectra of erbium doped fibre amplifiers (EDFA) is reported. The technique has been used to confirm homogeneous gain saturation in a broadband EDFA for output powers up to +10 dBm.

Spectral noise figure of Er/sup 3+/-doped fiber amplifiers

The erbium-doped fiber amplifier noise figure spectrum and its evolution under various pumping regimes is analyzed. The analysis shows that noise figures in the range +or-0.15 dB around the 3-dB quantum limit are possible within a spectral band of 50 nm. This demonstrates the possibility of quantum-limited amplification for broadband wavelength-division multiplexed (WDM) signals. >