Polarization-insensitive wavelength conversion up to 10 Gb/s basedon four-wave mixing in a semiconductor optical amplifier

Polarization-insensitive wavelength conversion at 2.5 and 10 Gb/s using four-wave mixing in a bulk semiconductor optical amplifier is reported. At 10 Gb/s, a conversion range from 6.4-nm wavelength downshift to 4.8-nm upshift has been demonstrated. The conversion efficiency and signal-to-noise ratio versus conversion range are also characterized     

Crosstalk characteristics of a 100 km-long splicedpolarisation-maintaining optical fibre

Crosstalk of -10.1 dB in a 100 km-long spliced polarisation-maintaining optical fibre has been achieved at 1.56 μm wavelength. The fibre has been constructed from 14 125 μm-diameter PANDA fibres, with an average modal birefringence of 4.8×10^-4 , by conventional arc-fusion splice techniques. An average transmission loss of 0.37 dB/km, including the splice loss, has been obtained at 1.56 μm wavelength     

Minimal group refractive index dispersion and gain evolution in ultra-broad-band quantum cascade lasers

The group refractive index dispersion in ultra-broad-band quantum cascade (QC) lasers has been determined using Fabry-Perot spectra obtained by operating the lasers in continuous wave mode below threshold. In the wavelength range of 5-8 /spl mu/m, the global change of the group refractive index is as small as +8.2 /spl times/ 10/sup -3/ /spl mu/m/sup -1/. Using the method of Hakki and Paoli (1975), the subthreshold gain of the lasers has furthermore been measured as a function of wavelength and current. At the wavelength of best performance, 7.4 /spl mu/m, a modal gain coefficient of 16 cm/spl middot/kA/sup -1/ at threshold and a waveguide loss of 18 cm/sup -1/ have been estimated. The gain evolution confirms an earlier assumption that cross-absorption restricted laser action to above 6 /spl mu/m wavelength.     

A new scheme for bidirectional WDM-PON using upstream and downstream channels generated by optical carrier suppression and separation technique

We propose a new bidirectional dense wavelength-division-multiplexing (DWDM)-based passive optical network using optical carrier suppression and separation technique to generate both upstream and downstream wavelength channels from a single laser. Thirty-two DWDM channels have been generated, and symmetric 10-Gb/s data transmission of a wavelength pair has been demonstrated.     

Nonlinear transmission of 20 Gbit/s optical time-division-multiplexed data, over 205 km of dispersion shifted fibre

Nonlinear pulse compression has been used to achieve transmission beyond the linear dispersion limit for 20 Gbit/s optical time-division-multiplexed data. Error free system operation has been achieved over an operating wavelength range of 10 nm above the wavelength of zero dispersion, in the anomalous dispersion regime.<>     

10-Gb/s agile wavelength conversion with nanosecond tuning timesusing a multisection widely tunable laser

Simultaneous wavelength conversion and high-speed wavelength switching has been demonstrated using a multisection grating-assisted coupler sampled reflector laser. A high-output extinction ratio (>20 dBm) over a 30-nm wavelength range was observed. The 10-Gb/s data was switched between different output wavelengths at a 2.5-Gb/s rate and transmitted over 50 km of dispersion-shifted fiber with a small measured power penalty (<2 dB)     

New low-loss liquid-core fibre waveguide

Low-loss liquid-core fibre-optical waveguides having a transmission loss of 10 dB/km has been made using commercially available glass tubing. The loss is less than 20 dB/km over a wavelength range of greater than 0.8?1.1 ?m, and, at the semiconductor laser wavelength of 0.9 ?m, has a value of 14 dB/km. This is the first low-loss fibre to be made using glass.     

Active DBR filters for 2.5 Gb/s operation: linewidth, crosstalk,noise, and saturation properties

The design of four-section distributed Bragg reflector (DBR) laser filters, for application in wavelength multiplexed systems with a 2.5 Gb/s bit rate on each wavelength channel, has been analyzed. The results of the analysis indicate that optimized filters will support at least 10 channels and will have a dynamic range exceeding 10 dB. Bit error rate (BER) measurements on three-section DBR filters in a 2.4 Gb/s system experiment support this conclusion     

Widely tunable 10 Gbit/s separate absorption and modulation Mach-Zehnder wavelength converter

A fully monolithic separate absorption and modulation region wavelength converter requiring no bias tees has been fabricated. The device consists of a transmitter comprising a sampled-grating DBR laser and series-push-pull Mach-Zehnder modulator, and a receiver composed of a linear semiconductor optical amplifier and a quantum well pin photodetector. The wavelength converter has a 13 GHz bandwidth and demonstrates error-free operation at 10 Gbit/s with unity gain     

Four channel integrated DFB laser array with tunable wavelengthspacing and 40-Gb/s signal transmission capacity

A four-channel distributed-feedback (DFB) laser array integrated with four heating filaments has been fabricated for high-density wavelength-division-multiplexing systems. The DFB lasers have a threshold current of 4 mA at room temperature. By changing the power in the heater, the wavelength of each laser can be continuously tuned by as much as 5 nm. Therefore, a tunable wavelength spacing anywhere from 1 nm to 2 nm can be achieved. Each laser can operate at 10 Gb/s. However, the bias current has to be increased to avoid the degradation of the eye pattern as the wavelength is thermally tuned over 2 nm. An electric crosstalk of 0.6 dB is measured when two adjacent lasers are modulated at 10 Gb/s simultaneously     

All-optical wavelength conversion with multicasting at 6/spl times/10 Gbit/s using electroabsorption modulator

All-optical wavelength conversion with multicasting has been demonstrated with a single electroabsorption modulator based on cross-absorption modulation. It is shown that the input signal wavelength can simultaneously convert to six different wavelengths at 10 Gbit/s, and the relation between the power penalty and the number of simultaneously operating channels is investigated.     

Widely tunable wavelength converter using a double-ring fiber laser with a semiconductor optical amplifier

Widely tunable wavelength conversion has been demonstrated using broad-band orthogonal-pump four-wave mixing in a semiconductor optical amplifier placed at the intersection of two fiber ring lasers. The all-optical wavelength converter operates without using any external pump source. A 3-dB conversion-range over 40 nm is obtained. The measured power penalty is 1.5 dB for a 2.5-Gb/s converted signal at 10/sup -9/ bit error rate.     

2×10 Gbit/s WDM 1310-nm optical transmission over 63.5-kmstandard single-mode fiber using optical preamplifiers

Twenty Gbit/s transmission over 63.5 km SMF at 1310 nm is reported by using two channel 10 Gbit/s wavelength (de)multiplexing (Δλ=1.5 nm). Two 1310 nm SL-MQW semiconductor optical amplifiers are utilized for loss compensation and sensitivity improvement. For the 1310 nm wavelength domain, a record bitrate x distance product of 1.27 Tbit/s.km has been obtained. Crosstalk penalties are identified, and the feasibility of an extension up to at least four, 10 Gbit/s channels is discussed     

560 Mbit/s transmission experiment using 1.3 ?m InGaAsP/InP LED

Using a high-speed InGaAsP/InP LED, 560 Mbit/s signal transmission over 4.4 km has been realised with a large-bandwidth graded-index fibre at 1.3 ?m wavelength and a bit-error rate of 10?9.     

Ultrahigh-Birefringent Bending-Insensitive Nonlinear Photonic Crystal Fiber With Low Losses

An ultrahigh-birefringent nonlinear photonic crystal fiber (PCF) that exhibits low losses and small effective mode area across a wide wavelength range has been presented. The effects of angular orientation on bending losses of the proposed PCFs have been thoroughly investigated by employing a full vectorial finite-element method (FEM). It has been demonstrated that it is possible to design a bending-insensitive nonlinear PCF with a birefringence $9times 10^{ - 3}$ at a 1.55-$mu$m wavelength. Significant improvements on key propagation characteristics of the proposed PCFs have been demonstrated by carefully altering the desired air hole diameters and the hole-to-hole spacing.      

Cascadability Performance Evaluation of a New NRZ SOA-MZI Wavelength Converter

We evaluate the cascadability performance of a new semiconductor optical amplifier (SOA) Mach-Zehnder interferometer-based nonreturn-to-zero wavelength converter in a loop experiment. We use the bidirectional data injection control scheme with an additional continuous-wave signal to optimize the gains and phases imparted by the SOAs. The scheme has been shown to be capable of eight cascaded, error-free wavelength conversions at 10 Gb/s.     

Eight-wavelength Er-Yb doped amplifier: combiner/splitter planarintegrated module

We report the successful operation of a pigtailed eight-wavelength planar integrated amplifying combiner. This device can be used in a splitter or in a combiner configuration. It consists in an 8×1 combiner and a 5.5-cm-long Er-Yb doped waveguide amplifier. The module provides net gain simultaneously to the eight combined wavelengths in the 1531-1546-nm optical bandwidth. This module has been incorporated in an 8×2.5 Gb/s wavelength-division-multiplexed (WDM) system. The central wavelength was 1535 nm and the channel spacing was 1 nm. Negative penalty for bit-error-rate performances (BER<10^-10) has been measured for each wavelength. The results of the system performance demonstrate the potential of the ion-exchange technology in providing cost effective integrated optic solutions for WDM networks applications     

Characteristics of Er-doped Al2O3 thin filmsdeposited by reactive co-sputtering

Er-doped Al₂O₃ thin films have been deposited by reactive co-sputtering onto thermally oxidized Si-wafers. The deposition process has been optimized with respect to the requirements originating from the application of these multilayer structures as integrated optical amplifiers for the third telecom window, i.e., the wavelength range 1.52-1.55 μm. The films obtained at a substrate temperature of only 400°C are amorphous and show a homogenous structure, without columns or grains. For slabguides, background losses smaller than 0.25 dB/cm have been obtained, even without any annealing. A relatively broad luminescence band, having an FWHM of ~55 nm around the 1.533-μm wavelength, has been measured. From gain versus pumping power curves, an upconversion coefficient lower then 20·10^-25 m³/s has been derived, being half of the values reported up to now in the literature. Simulations based on experimentally determined material parameters and assuming a channel attenuation of 0.5 dB/cm indicate, for 0.24 at.% Er channel devices with an optimal channel length of 7.7 cm, an amplification of 8 dB at 1.533 μm for a pump wavelength of 1.48 μm, and a pump power of only 8.7 mW     

Integrated optical Ti:Er:LiNbO3 soliton source

Efficient diode-pumped and harmonically mode-locked operation of a fully packaged Ti:Er:LiNbO₃ waveguide laser at 1562- (TE) and 1575-nm (TM) wavelength has been demonstrated. The mode-locked pulses have been characterized in terms of time-bandwidth product, fine tuning, and stability. Noise suppression of 42 dB at the relaxation oscillation frequency has been achieved by feedback-controlled pumping. An external amplitude modulator has been used for encoding of the mode-locked pulse train with different bit sequences. Bit error rates of 10^-10 for a 1-0-1-0-bit sequence has been observed for more than half an hour     

Photodetection using photomagnetoelectric and Dember effects in gold-doped silicon

Photodetection in the visible and near IR wavelength region using photomagneto-electric and Dember effects in gold-doped silicon has been demonstrated in this note. Response time trof 0.2 µs and noise equivalent power (NEP) of 6 × 10^-10for a photomagnetoelectric (PME) cell, and tr< 0.03 µs and NEP = 2.5 × 10^-10for a Dember cell, were obtained from the present results.