Amplified spontaneous emission

An erbium-doped (Er-doped) fiber amplifier operating in the C-band is gain clamped, at about 26 dB with noise figures below 6 dB by multiple fiber Bragg gratings. These gratings are placed at the amplifier output with center wavelengths in between communication channels so that unwanted amplified spontaneous emission is removed but put to good use. A 0.5-dB gain compression point at -15 dBm of input signal powers for two simultaneous signal channels is also demonstrated.

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Using a modified version of the split-step Fourier method, we analyze the effect of noise on soliton propagation inside erbium-doped fiber amplifiers. In fact, noise from forward-propagating amplified spontaneous emission, associated with a Markov immigration process, is included in the analysis of soliton amplification. Moreover, this algorithm accounts for the real spectral gain profile of the fiber amplifier. The frequency jitter, induced during soliton amplification, is compared with the Gordon-Haus effect where optical amplifiers are considered as noisy point-like devices

L-band gain improvement through usage of secondary pumping sources in the form of amplified spontaneous emission (ASE) was conducted. Gain improvement as high as 6 dB was achieved. However, pumping the system directly with ASE would inevitably incur a noise figure penalty; in this case as much as 1 dB. For a system utilising ASE to improve L-band amplification, pumping the system counter-directionally with ASE while a 980 or 1480 nm pump is used in a co-propagating manner would yield the best overall system performance

A SiO2/SiOx/SiO2 strip-loaded waveguide with buried Si quantum dots is optically pumped to provide amplified spontaneous emission centered at 805 nm with spectral linewidth of 140 nm. By top-pumping the 350-nm-thick SiOx with He–Cd laser of 40 mW at 325 nm, the optical gain of 65 cm−1 and loss coefficient of 5 cm−1 are determined. Under a 785 nm small-signal

A diode-pumped laser amplifier model is derived from first principles and applied to a Nd:YAG amplifier operating on the 4F 3/2 to 4I 9/2 transition at 0.946 mum. The effects of amplified spontaneous emission are included in the model and the addition of this effect is shown to produce better agreement with the data. The amplifier model includes effects of the transverse and longitudinal variation of the pump beam, transverse and longitudinal variation of the probe beam, and multiple passes of the probe beam. Experimental results obtained with a quasi four-level Nd:YAG amplifier operating at 0.946 mum are used to validate the model. The amplifier was evaluated as a function of the pump energy, the probe energy, the probe beam radius, the pulse repetition frequency and the temperature. For all of the experimental conditions, the experimental results and the model agree.

A new, simple method for the generation of Xe6s3/2 1 and Xe6s1/2 1 atoms is described. The method involves resonant two-photon excitation of Xe6 p1/2 0 and 6 p3/2 2 states followed by amplified spontaneous emission ASE to the Xe6s3/2 1 and 6s1/2 1 states. The vacuum ultraviolet transitions, Xe(6s[3/2] 1 →5p 6 (1 S 0)) at 147 nm and Xe(6s[1/2] 1 →5 p 6 (1 S 0)) at 129.6 nm, were used to monitor the time dependence of the resonance state atom concentrations. The quenching rate constants of these resonance atoms with ten molecules were measured at 300 K. The quenching cross-sections of the Xe6s and 6s resonance atoms are compared to the cross-sections of the metastable Xe6s3/2 2 atoms and Xe6p3/2 2 atoms. The correlation between quenching cross-sections and photoabsorption cross-section of the molecules predicted by the resonance dipole–dipole energy transfer model is discussed. The applicability of the two-photon driven ASE method for the generation of other resonance state atoms is considered.

An optical preamplifier system consisting of a 27dB-gain erbium-doped fiber amplifier, a three-port circulator and a 47GHz bandwidth in-fiber grating has improved receiver sensitivity and consequently sensor range of a spontaneous Brillouin-based fiber-optic distributed temperature single-ended sensor. Optical signal-to-noise has improved by 17dB. Using this system and operating at 1533nm, a sensor with a range of 23km, spatial resolution of 1.8m, measurement time of 9 minutes and temperature resolution of 6K was implemented. The temperature resolution was attributed to contamination of the backscattered spontaneous Brillouin signal by the residual Rayleigh signal after optical filtering. The optical signal-to-noise is supported theoretically by considering associated noise sources.