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1.
We demonstrate a new, fast, and stable all-optical fiber switch based on the TOAD principle. It utilizes a transient thermal phase shift induced by a short pump pulse to cause switching in a cobalt (Co)-doped fiber placed in a Sagnac fiber loop. Switched pulses as short as 7-ns were observed in a 2-m loop containing a 2.55-cm length of Co-doped fiber pumped with 12-ns pulses. Compared to other all-optical switches using doped fibers, this switch offers a dramatic increase in speed and stability, and a sizable reduction in fiber length requirement  相似文献   

2.
Time-resolved numerical analysis of a nonlinear Sagnac interferometer switch (NSIS) reveals that the combined effects of group velocity dispersion (GVD), self phase modulation, cross phase modulation, and pump-probe walk-off seriously degrade switching performance when the soliton number N of the pump pulse is under 5. This means that the peak power of short pump pulses cannot be reduced to less than the critical value at N>5 to prevent the effect of GVD. This restriction is more severe for pump pulses in the anomalous dispersion region than for those in the normal dispersion region because of higher-order soliton compression. System designs for time-division demultiplexers that use NSISs and picosecond pump pulses generated by a laser-diode coupled to erbium-doped fiber amplifiers are discussed. It is found that 1:32 demultiplexing from 160 to 5 Gb/s and 1:8 demultiplexing from 80 to 10 Gb/s with a switching contrast of more than 60 are possible using diode-laser-pumped 1- and 2-ps pump pulses, respectively  相似文献   

3.
A Sagnac interferometer consisting of a semiconductor laser amplifier and a 3 dB coupler monolithically integrated within a waveguide loop mirror is fabricated and its application as a 20 Gbit/s all-optical demultiplexer is demonstrated  相似文献   

4.
Nonlinear Sagnac interferometer switch and its applications   总被引:5,自引:0,他引:5  
Ultrafast all-optical switching based on the optical Kerr effect in a Sagnac interferometer which consists of a dichroic polarization-maintaining fiber coupler and dispersion-shifted polarization-maintaining fiber loop is reported. This nonlinear Sagnac interferometer switch has the advantage of high stability originating from completely balanced interfering arms. In addition, because dispersion-shifted fibers were used, increases in switching power and switching time were prevented. Moreover, polarization fluctuation was completely suppressed due to the all-polarization maintaining fiber configuration. The required switching power for complete switching was measured to be 1.8 W for a 200-m-long fiber. All-optical time division demultiplexing and logic operations, including inversion and operation, using the nonlinear Sagnac interferometer switch were successfully demonstrated at 5 Gb/s  相似文献   

5.
An ultrafast, low-power, and highly stable all-optical switch in a nonlinear Sagnac interferometer is reported. To achieve low-power, highly stable, and walkoff free switching, use is made of a small-core dispersion-shifted polarization-maintaining fiber loop (200 m in length) which has a small group delay difference between the wavelengths of the input signal and the control pulse. To achieve complete polarization stability, a wavelength-sensitive polarization-maintaining fiber coupler is employed. Highly stable and walkoff free all-optical switching is demonstrated at 5 Gb/s  相似文献   

6.
A Sagnac interferometer integrated with a parallel-amplifier structure (SIPAS) is proposed for filter-free all-optical wavelength conversion. A Mach-Zehnder interferometer with a semiconductor optical amplifier in each arm is monolithically integrated with a Sagnac interferometer. Clear eye opening and low power penalty of 0.9 dB were achieved at a bit rate of 10 Gbit/s using the fabricated SIPAS.  相似文献   

7.
Ultrafast all-optical switching with a switching power of 14 W was demonstrated in a Kerr shutter configuration using a single-mode As2S3-based glass fiber only 48 cm long. The nonlinear refractive index of the fiber was evaluated from the switching characteristics to be n2=4.2×10-14 (cm2/W), which is higher by two orders of magnitude than silica glass fiber  相似文献   

8.
All-optical signal regularizing/regeneration using a nonlinear fiber Sagnac interferometer switch (NSIS) that employs signal-clock walk-off is investigated. The NSIS realizes all-optical signal regeneration, including timing and amplitude regularizing, by switching clock pulses with amplified input signals using a walk-off-induced, wide, square switching window and intensity-dependent transmittance of the device. First, characteristics (in both the temporal and spectral domains) of the all-optical signal regeneration achieved with the NSIS are investigated theoretically and experimentally. They certify that if clock pulses are within the square switching window obtained with signal-clock walk-off, the clock pulses can be modulated according to the data that the input signals carry and retain their temporal and spectral profiles. This means that if clock pulses can be prepared that meet the system requirements, the NSIS can convert input signals that may not satisfy system requirements into high-quality output signals. Limitations on the switching contrast due to the cross-phase modulation of counterpropagating reference pulses is also discussed. Second, two possible applications of NSIS-based all-optical signal regularizing/regeneration, 1) an all-optical multiplexer with an optical clock and 2) an all-optical regenerative repeater, are discussed. Preliminary experiments with ~10-ps pulses at bit rates of ~5 Gb/s that use locally prepared optical clock pulses, show that the NSIS provides an error-free regeneration function with a certain tolerance for pulse-period irregularity if a proper optical clock is obtained  相似文献   

9.
An approach based on linearization that allows us to calculate the timing and amplitude jitter for arbitrary pulse shapes in dispersion-managed fibers is developed. We apply this approach to calculate the jitter for dispersion-managed soliton, return-to-zero (RZ), and nonreturn-to-zero (NRZ) transmission formats. We then estimate the bit error rates. The approach described here yields more precise results than Monte Carlo simulations at a fraction of the computational cost  相似文献   

10.
A routing all-optical switch in which the signal, consisting of a fundamental soliton, is directed into either of the output ports of a 2×2 nonlinear directional coupler is investigated by means of computer simulation. The routing is controlled by copropagating a controlling pulse along with the signal pulse. Four different schemes for doing this are explored where the polarization of the controlling pulse with respect to the signal soliton may be varied, or the controlling pulse may be launched into either of the input ports, or it may have a wavelength different from that of the signal. It is shown that only one of the schemes allows a high switching efficiency and enables distortionless propagation of the signal pulse through the coupler  相似文献   

11.
This paper reports on timing-jitter analysis of an all-optical clock-recovery scheme at 40 GHz using self-pulsating (SP) lasers. Based on the analogy with injection locking of oscillators, theoretical investigations on phase-noise properties of the recovered clock lead to the demonstration of a filtering function with slope that is compliant with the International Telecommunications Union (ITU) standards and allow us to underline the dependence of the cutoff frequency of the filtering transfer function on the spectral linewidth of the free running SP laser. From this phase-noise analysis, an analytical expression of the timing jitter of the recovered clock is derived, including the optical signal-to-noise ratio (OSNR) of the injected signal. A set of experiments on all-optical clock recovery at 40 GHz is then presented and demonstrates the crucial role of the spectral linewidth on the timing-jitter-filtering function of the SP laser. In good agreement with theoretical results, the impact of the OSNR degradation of the injected signal on the timing jitter is also demonstrated. Finally, the all-optical clock-recovery operation using a quantum-dot SP laser is shown to be standard compliant in terms of timing jitter, even for highly degraded OSNR.  相似文献   

12.
We demonstrate measurements of fundamental thermal induced phase fluctuations in the fiber-loop of a Sagnac interferometer. Loop lengths of 1.1 and 2.2 km are considered, showing phase noise levels between ~0.2-1.4 μrad rms/√(Hz) in the frequency range 1-100 kHz. Good agreement between theory and experiment is demonstrated. We show that the frequency dependent noise floor can have a considerable impact on threshold detection's for a Sagnac based sensor for detection of reciprocal measurands, as well as on the random walk coefficient in fiber optic gyroscopes  相似文献   

13.
Multi-wavelength fiber ring laser based on the semiconductor optical amplifier(SOA)with sampled fiber Bragg grating(SFBG)in a Sagnac loop interferometer as the wavelength-selective filter is proposed.Four lasing wavelengths with 1.8 nm spacing have been generated stably at room temperature.The proposed laser has the advan-tages such as removal of the high-cost circulator,flexibility in channel-spacing tuning,and simple all-optical fiber configuration,which has potential applications in high-capacity wavelength-division-multiplexed(WDM)systems and mechanical sensors.  相似文献   

14.
理论推导了基于光纤中四波混频效应的全光波长变换效率公式,利用OptiSystem成功模拟出了基于非线性色散光纤的全光波长变换.通过调整抽运光与信号光的频率差、抽运光功率、光纤衰减系数、光纤的有效面积等参量,获得了变换效率为15.4dB的变换光.  相似文献   

15.
A method for determining the eigenfrequencies of the fiber coils used in sensors based on a Sagnac interferometer is proposed. In this method, the fiber coil is used as the main part of an external resonator of a laser diode. The method is simple and reliable, and a high accuracy of measurements is ensured.  相似文献   

16.
本文对光纤非线性效应的物理机理做了理论分析,并在此基础上,利用optisystem仿真平台和matlab编程软件联合仿真实现了基于光纤非线性效应的几种全光再生方案,仿真结果与理论分析吻合。  相似文献   

17.
A high-speed, polarization independent, electrooptic tunable filter was built using a birefringence modulator within a Sagnac interferometer. Switching times less than 0.5 ns were achieved in our experiment for this filter. Application in highspeed wavelength routing was also demonstrated.  相似文献   

18.
The performance of current optical networks is inherently limited by the speed of electronic components and, in particular, by electronic switches. A new generation of optical networks, referred to as all-optical networks, overcomes this limitation by switching data entirely optically using all-optical crossconnects (OXCs). However, all-optical networks are prone to phenomena that are unknown to current optical networks with electrical regeneration: OXCs are subject to optical leaks, called crosstalk, resulting in unwanted components being added to transmitted signals, and this crosstalk is transmitted over very long paths without any signal regeneration. In this paper, we consider the interplay between fiber nonlinearity and crosstalk signals over long distances as the source of performance degradation, measured in terms of Q factor. We present an analytical crosstalk model for all-optical networks and give expressions for the performance degradation resulting from the joint propagation of a signal [using a continuous-wave (CW) assumption and perturbation theory] and crosstalk in large networks. Analytical calculations required by this model are shown to be much less computationally intensive than simulations. Simulations are carried out to validate our analytical model and good agreement is found between the analytical model and simulations for wide ranges of parameters.  相似文献   

19.
In this paper a novel structure based on Mach-Zehnder Interferometer (MZI) and an array of nonlinear ring resonators for all-optical switching including very low threshold, fast and all-optically tunable is presented. In this proposal, an array including N ring resonators is coupled to one arm of MZI to introduce the required nonlinear phase shift to switching. Also, two-photon absorption phenomenon is used and will be proposed as another alternative for manipulation of optical switching properties. The proposed idea needs small chip area (∝1/Ntraditional cases) for implementation. We show that the switching threshold intensity can be decreased with increase of N, decrease of the coupling coefficient and increase of the two-photon absorption coefficient. In this structure with traditional optical fibers with the low nonlinear index of refractions and using an array including 15 ring resonators with 6 mm diameter for each rings only 3 mW for the switching threshold power is required. Also, using erbium-doped fiber for implementation of the rings with the high nonlinear index of refractions and five ring resonators including 0.3 mm diameter, the switching threshold power can be reduced to μW level. If the nonzero two-photon absorption coefficient is considered, the switching threshold will be very smaller than the above-mentioned values. We show that with changing the optical amplifier gain the switching threshold can be tuned. So, the proposal can be used as a functional block for the integrated optical switch with very small and tunable threshold.  相似文献   

20.
We report on an all-optical demultiplexer based on gain-transparent operation of a semiconductor optical amplifier (SOA) in an ultrafast-nonlinear interferometer (GT-UNI). The GT-UNI comprises a robust fiber-chip setup in a folded geometry. For switching window widths of 5.2 ps and 6.0 ps, error-free demultiplexing of 160-10 Gb/s is demonstrated  相似文献   

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