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Integrated waveguide amplifiers based on high concentration Er3+ doped BaY2F8 crystals are numerically studied by combining a full-vectorial finite element based modal analysis and propagation-rate equations. Using realistic input data, such as the absorption/emission cross sections and Er level lifetimes measured on grown crystal samples, we investigate the amplifier performance by optimizing the total Er concentration. We predict optimum gain coefficient up to 5 dB/cm and broad amplification bandwidth exceeding 80 nm with 1480 nm pumping. [ABSTRACT FROM AUTHOR]

A full-vectorial finite element based modal analysis and propagation-rate equations are used to study the integrated waveguide amplifiers based on high concentration [Er.sup.3+] doped Ba[Y.sub.2][F.sub.8] crystals. The numerical results have predicted optimum gain coefficient up to 5 dB/cm and broad amplification bandwidth exceeding 80 nm with 1480 nm pumping.

We present the experimental results of thermally tunable double microring resonator devices for integrated wavelength division multiplexing applications. The devices demonstrated a free-spectral range up to 2.4 THz (19.2 nm) around 1550 nm and a channel rejection higher than 35 dB. Using Ti/TiN metal heaters, a power consumption of 20 mW per FSR per ring is achieved, which outperformed analogous devices fabricated using the standard silicon process. A thermal tuning efficiency of 0.95 nm/mW is accomplished, and a symmetric tuning is obtained with less than 1% of electrical compensation. [ABSTRACT FROM AUTHOR]

We present the design procedure and experimental results of thermally tunable double ring resonators for integrated wavelength division multiplexing applications. A detailed analytical model specific for double rings is described, and a modified racetrack geometry using Bezier bends is used to reduce bending loss. We demonstrate devices with a free-spectral-range up to 2.4 THz (19 nm) around 1550 nm and nonadjacent channel rejection higher than 35 dB. The experimental results of thermally tunable double ring resonators is also presented with doped silicon integrated heaters, allowing the device to be used as a tunable filter or a switch. [ABSTRACT FROM PUBLISHER]

We present a theoretical and experimental analysis of the sensing capabilities of Raman-based distributed temperature optical fiber sensor (RDTS) systems using only the anti-Stokes (AS) component in loop configuration. In particular, the effects of time- and wavelength-dependent losses on the sensor performance are thoroughly investigated under different experimental conditions. As expected from the developed theory, experimental results demonstrate that using the loop AS-light only approach in RDTS systems can correct the impact of local and wavelength-dependent losses on the final temperature measurements, with the simple use of an internal calibration fiber spool at a known temperature value. Signal-to-noise ratio and temperature resolution analyses of the AS-only RDTS point out an improved temperature resolution in comparison to standard RDTS systems in loop configuration. [ABSTRACT FROM PUBLISHER]

We numerically investigate the potential of Al2O3:Er^3+ active slot waveguides for realizing small-form factor lasers on silicon on insulator at 2.8 \mum. Based on recent technological improvements in the reliable and low-cost fabrication of alumina doped with high Er^3 + concentration and exploiting the extremely high field intensity achievable in optimized active slot waveguides, we point out the possibility of realizing silicon-compatible emitters at 2.8 \mum, optically pumped at 1480 nm with a few milliwatts threshold pump power. A strong potential impact can be envisaged for chemical sensing, biosensing and lab-on-a-chip applications. [ABSTRACT FROM PUBLISHER]

We present a multimode longitudinal pumping scheme for integrated rare-earth-doped waveguide amplifiers which allows an efficient use of low cost multimode pump sources. The scheme is based on evanescent pump light coupling from a multimode low loss waveguide to a single mode active core. Multimode pump light is gradually coupled to the active waveguide, which is single mode at the signal wavelengths, providing population inversion along the whole amplifier length and overcoming the main limitation of conventional single mode pump butt-coupling in case of strongly absorbing active materials. We propose this pumping scheme at 477 nm for Si-nanocluster sensitized Erbium doped waveguide amplifiers, in which conventional butt-coupling is inefficient due to the strong pump absorption by the Si- nanoclusters , and top pumping by LED arrays is limited by the low pump intensity values achievable within the active region. The coupling between the multimode waveguide and the active core has been numerically studied for slab waveguide structures using a 2-D split-step finite element method. [ABSTRACT FROM PUBLISHER]

We compare standard fiber Raman laser and new high-power- and low relative-intensity-noise (RIN)-copumping technologies for long-span unrepeated wavelength-division-multiplexing (WDM) transmission systems. We show that, by using enhanced forward-error-correction techniques and by optimizing the transmission-system parameters in terms of signal power per channel, dispersion map, and copropagating on- off Raman gain, both copumping technologies allow successful transmission of 8 10-Gb/s WDM channels over more than 70 dB of standard single-mode fiber. However, transmission experiments point out that only the newly proposed high-power and low-RIN lasers can guarantee realistic system margins and can potentially provide further span-reach enhancement when used in optimized higher order copumping configurations. [ABSTRACT FROM PUBLISHER]

Benefits provided by higher order bidirectional Raman pumping schemes in 10-Gb/s unrepeated wavelength-division-multiplexing transmission systems are experimentally quantified in terms of BER performances at 10 Gb/s. By keeping under control double-Rayleigh-scattering-noise-induced transmission penalties, which can degrade system performance at very high ON-OFF Raman gain, as well as nonlinear propagation effects such as Brillouin scattering, self- and cross-phase modulations, four-wave-mixing, and Raman-induced crosstalks, we show a total unrepeated system reach enhancement up to 3.5 dB with respect to first-order bidirectional pumping. As confirmed by theory, the maximum reach enhancement is mainly limited by pump-to-signal relative intensity noise transfer induced by higher order copumping. [ABSTRACT FROM PUBLISHER]

Measurements of the microwave Hall mobility of semiconductors have been performed by an improved contactless method at 20 GHz by using a bimodal cavity resonator and a two-channel vector network analyzer. Data analysis was performed by using generalized expressions for the mobility, taking into account different coupling values on the two ports and a nonlinear response due to high magnetic fields in samples with mobility from thousands of cm[SUP2]/V s. For several samples, Hall microwave and dc measurements have been compared, confirming the reliability of the proposed method; the characterization of bulk n-ZnSe and modulation-doped n-Al[SUB0.33]Ga[SUB0.67]As/GaAs two-dimensional electron gas samples is in particular presented. This method appears particularly suitable for the experimental determination of magnetotransport properties of semiconductor materials, especially when good electric contacts are difficult to be realized. [ABSTRACT FROM AUTHOR]

We numerically investigate the potential of Al2O3 : Er^3+ active slot waveguides for realizing small-form factor lasers on silicon-on-insulator. Based on recent technological improvements in the reliable and low-cost fabrication of alumina doped with high Er^3+ concentration, we point out the possibility of realizing silicon compatible emitters at 1.55 \mum, optically pumped at 1480 nm with a few milliwatts threshold pump power. [ABSTRACT FROM PUBLISHER]

We experimentally investigate dynamic bit-error rate (BER) performance impairments induced by add-drop operations in semiconductor-optical amplifer (SOA)-based wavelength-division-multiplexing (WDM) metro-ring networks. Link control techniques in short-medium span networks provide effective performance improvement and significant BER transient reduction during add-drop operation, with respect to SOA linear operating condition (low input signal power). This behavior is confirmed by dynamic BER measurements and optical signal-to-noise penalty analysis. [ABSTRACT FROM PUBLISHER]

We present a longitudinal multimode pumping scheme which allows Yb-sensitized Er-doped silica waveguide amplifiers to be effectively pumped by high-power and low-cost broad-area lasers. The proposed configuration is based on evanescent pump light coupling from a multimode low-loss waveguide to a Er-Yb codoped active core. Theoretical predictions, based on propagation and population-rate equations for the coupled Er-Yb system, show that longitudinal multimode pumping by high-power broad-area lasers at around 980 nm can provide up to 4-dB gain per centimeter, suggesting possible integration of low-cost amplifiers with important applications in wavelength-division-multiplexing metro and access optical networks. [ABSTRACT FROM PUBLISHER]

We experimentally study the performance of wavelength-division-multiplexing (WDM) metro/access ring networks, based on semiconductor optical amplifiers (SOAs), considering several gain control techniques. We show that gain control through link-control (LC) channel or amplified spontaneous emission (ASE) power recirculation, effectively used in erbium-doped fiber amplifier-based WDM ring networks, introduces serious penalties due to intensity noise transfer, and cannot be used in short-span SOA-based WDM rings. On the other hand, we observe a net benefit using LC channel and ASE extraction for short span rings and a limited WDM channel number, compared with linear operating conditions. An effective optical signal-to-noise ratio improvement of 2.1 dB has been achieved with LC channel extraction with respect to linear operation, for a 4 x 13.5 dB span ring with eight WDM channels. For spans longer than 15 dB, system performance in gain-controlled rings is found to be similar to noncontrolled ones. [ABSTRACT FROM PUBLISHER]

A distributed sensor system employing spontaneous Raman scattering with use of correlation-coding techniques and a single-detector scheme is discussed and experimentally characterised. A sensing distance of up to 8 km is achieved with high spatial and temperature resolutions; use of correlation-coding significantly reduces measurement time and allows use of low-power laser sources. [ABSTRACT FROM AUTHOR]

We propose a novel high-power (up to 1.9 W) and low relative intensity noise (RIN) laser structure for effective first- and higher order distributed Raman copumping. RIN characterization and bit-error-rate measurements at 10 Gb/s point out RIN-penalty free transmission up to 25 dB of on-off copropagating Raman gain. This new copumping technology can provide sensible span reach enhancement in long-span unrepeated WDM transmission systems in a simple and effective way [ABSTRACT FROM PUBLISHER]

We propose a second-order counterpumped Raman ring fiber oscillator for high gain and low noise discrete Raman amplification with enhanced robustness to wavelength-division-multiplexing channels add-drop operations. Bit-error-rate measurement at 10 Gb/s shows negligible penalties up to 20-dB net gain. [ABSTRACT FROM PUBLISHER]

We discuss penalties induced by pump intensity noise transfer and parametric nonlinear interactions in counterpumped distributed Raman amplifiers based on nonzero dispersion shifted fibers. An effective suppression of penalties induced by parametric nonlinear interaction is experimentally demonstrated by a new Raman pump module, based on cascaded fiber Raman lasers. [ABSTRACT FROM PUBLISHER]