160-Gb/s optical sampling by gain-transparent four-wave mixing in asemiconductor optical amplifier

We report on a broad-band all-optical switch that exhibits high linearity (>30 dB), high switching contrast (>25 dB), and large data wavelength tunability (100 nm). The switching principle is based on four-wave mixing. Two control pulse trains are placed in the gain wavelength region of a 1300-nm semiconductor-optical amplifier. The data signal, however, is at 1550 nm in the transparent wavelength region where four-wave mixing sidebands are generated due to index modulations. The switch is used to sample a 160-Gb/s data signal with a temporal resolution of approximately 1.7 ps     

Optical sampling using nondegenerate four-wave mixing in asemiconductor laser amplifier

Picosecond optical sampling using nondegenerate four-wave mixing in a semiconductor laser amplifier (SLA) is demonstrated for the first time. High-peak-power pulses and electrical gating of the SLA produce an optical sampling signal with a high signal-to-noise ratio     

Time-delay characteristics of four-wave mixing among subpicosecondoptical pulses in a semiconductor optical amplifier

We have studied four-wave mixing (FWM) characteristics among subpicosecond optical pulses in a semiconductor optical amplifier for different time-delays between pump and probe beams, for the first time. Our experimental results have shown that an optimum time-delay shifted from the perfect pump-probe overlap condition with an increase in input probe beam energy. An optimum intensity of the pump beam has also been obtained to generate the maximum FWM signal     

Theory of nondegenerate four-wave mixing between pulses in asemiconductor waveguide

We develop a perturbation theory for calculating the effects of saturation on nondegenerate four-wave mixing between short optical pulses in a semiconductor optical amplifier. Saturation due to ultrafast intraband dynamics like carrier heating and spectral hole burning is found to be important for pulses on the order of 10-20 ps or less     

Highly nondegenerate four-wave mixing among subpicosecond opticalpulses in a semiconductor optical amplifier

We have demonstrated, for the first time, the highly nondegenerate four-wave mixing (FWM) among subpicosecond optical pulses in a 1.3-μm multiple-quantum-well (MQW) semiconductor optical amplifier (SOA). We could directly measure the FWM signal in the output spectrum by current pulse pumping of the device. We achieved a high conversion efficiency of over 10% at a frequency conversion range of less than 1 THz. The limitation of conversion efficiency due to the gain saturation of the SOA was effectively overcome by using the short optical pulses     

A simple method to determine carrier recombinations in asemiconductor laser optical amplifier

The contribution of nonradiative carrier recombinations to the characteristics of long-wavelength InGaAsP/InP semiconductor laser devices is verified by measuring the amplified spontaneous emission (ASE) power from a 1.5-μm semiconductor laser amplifier (SLA) against the bias current. This method provides a simple and straightforward way to determine the mathematical form of recombination rate in a long-wavelength semiconductor laser, provided that the structural parameters of the laser are known     

Experimental investigation on slow light via four-wave mixing in semiconductor optical amplifier

Optical buffer is a key component in all optical information processing systems.Slow light at room temperature via four-wave mixing (FWM) in semiconductor optical amplifier (SOA) is experimentally investigated.Time delay of 0.40ns is achieved for a sinusoidal modulation signal at 0.1 GHz, corresponding to a delay bandwidth product (DBP) of 0.04.Factors that affect the experimental results are discussed.It is found out that the variable optical delay via FWM in SOA can be controlled either electrically by changing the SOA bias or optically by varying the pump power or pump-probe detuning.     

All-optical wavelength shifting of microwave subcarriers by using four-wave mixing in a semiconductor optical amplifier

We demonstrate all-optical wavelength shifting over 9 nm for two microwave subcarriers by using four-wave mixing in a semiconductor optical amplifier. In our experiment, the RF spectrum is relatively unaffected by wavelength shifting and the resultant system power penalty is /spl sim/0.5 dB. Such a transparent wavelength shifter may be a critical component in WDM networks supporting both subcarrier multiplexed (SCM) and high speed digital transmission.     

Folded-path self-pumped wavelength converter based on four-wave mixing in a semiconductor optical amplifier

A four-wave mixing wavelength converter with no external pump laser and very low input signal power requirements is characterized. The wavelength conversion occurs inside a high-reflection/antireflection coated semiconductor optical amplifier pigtailed with a fiber Bragg grating. The pump signal is provided by the lasing mode at the Bragg wavelength. A 1-mW optical signal modulated at 2.5 Gb/s is converted over 9 mm with error rates below 10/sup -9/.     

Ultrahigh-speed reconfigurable logic gates based on four-wave mixing in a semiconductor optical amplifier

We have demonstrated simple reconfigurable all-optical logic operations based on four-wave mixing in semiconductor optical amplifier and encoding information in the polarization of the input signals. Experimental implementation of six logic functions (including XOR, XNOR, AND, NOR, etc.) operating at 10 Gb/s were realized by simply adjusting two polarization controllers in the setup.     

Laser mirror by degenerate four-wave mixing in a saturable amplifier

A phase conjugate mirror by degenerate four-wave mixing in a saturable gain medium has been successfully operated in a pulsed laser cavity. This mirror works with low-intensity pump beams when they are resonant with the nonlinear medium. The pump beams can thus be delivered by a continuous-wave, frequency stable laser of low power. In such a device, the pulsed laser emission displays automatic frequency locking to the pump waves without cavity length stabilization.     

Isolas in four-wave mixing optical bistability

Optical bistability based on the cross-interaction of two counterpropagating plane waves in a Kerr-like medium is considered. It is shown that the "input-output" characteristics of such a system have not only multivalued hysteretic response (which was demonstrated by Winful and Marburger in 1980), but also multiple isolated branches (so called isolas) with nonhysteretic jumps from these branches to the main curve (but not vice versa). The isolas were found both in the case in which the problem can be solved analytically (particularly for electrostriction mechanism of optical nonlinearity) and in the general case of arbitrary light-induced anisotropy.     

Cascaded wavelength conversion by four-wave mixing in a strained semiconductor optical amplifier at 10 Gb/s

We demonstrate for the first time cascaded wavelength conversion by four-wave mixing in a semiconductor optical amplifier. Bit-error-rate performance of <10/sup -9/ at 10 Gb/s is achieved for two conversions of up to 9 nm down and up in wavelength. For two wavelength conversions of 5 nm down and up, a power penalty of 1.3 dB is measured. A system of two wavelength converters spanning 40 km of single-mode fiber is also demonstrated.     

Quaternary optical packets generated by fiber four-wave mixing

Recent work suggests that fiber four-wave mixing may be used to merge two wavelength multiplexed binary channels into a single quaternary signal. In this letter, we investigate the application of this technique to the optical packets generation considering that a 10-Gb/s payload is optically multiplexed to a 2.5-Gb/s label. Computer simulations are used to analyze the propagation of the generated quaternary optical packet in the dominance of amplified spontaneous emission noise. Results suggest that the optical packet may be propagated through metropolitan area networks length scales and that an average power around 0 dBm should be used to minimize the packet bit-error rate.     

同向泵浦拉曼放大器中泵浦-信号间四波混频研究

研究了同向泵浦分布式拉曼放大器(DRA)中泵浦-信号间的四波混频(FWM)效应.基于分段求和法,导出了不同零色散波长光纤组成的前向泵浦DRA中FWM功率的计算公式.考虑受激拉曼放大的情况下,数值模拟了DRA中FWM引起的信道串扰随光纤传输距离的演变,以及FWM与光纤零色散波长之间的关系.理论分析了色散补偿光纤(DCF)对FWM串扰的抑制效应.计算结果表明,在采用非零色散位移光纤(NZDSF)作为传输介质的DRA中,泵浦-信号间存在着较强的FWM效应,严重影响了密集波分复用(DWDM)系统的传输性能.引入适量DCF,不仅能降低DRA中FWM引起的信道串扰,还可有效消除色散导致的波形失真.     

Investigation of 3D semivectorial finite-difference beampropagation method for bent waveguides

A three dimensions of semivectorial finite difference beam propagation method (FD-BPM) in cylindrical coordinates is investigated in order to analyze the optical wave propagation in the bent waveguides with the strong lateral confinement which will keep low radiation loss. The three dimensional (3D) semivectorial wave propagation equation is programmed in the quick and unconditionally stable procedure by using the alternating direction implicit method. This version of FD-BPM could well express the polarization characteristics of modal field near the dielectric interfaces and accurately simulate the wave propagation in bent waveguides even at a very small radius (<100 μm). Moreover, it is pointed out that the numerical precision of the algorithm is intensively affected by the propagation loss of bent waveguides along with the propagation step length of beam propagation method     

Polarization-independent wavelength conversion at 2.5 Gb/s by dual-pump four-wave mixing in a strained semiconductor optical amplifier

We give a general expression for the polarization dependence of the four-wave mixing (FWM) efficiency in the dual-pump configuration. This expression, along with some general properties of the FWM susceptibility tensor, is used to propose a simple scheme to generate a nearly (1.5-dB variation) polarization independent FWM converted signal. The viability of this scheme is verified in a wavelength conversion experiment at 2.5 Gb/s.     

A novel method for polarization insensitive four-wave mixing in semiconductor optical amplifiers

A new method for obtaining polarization insensitive four-wave mixing with phase inversion in a semiconductor optical amplifier is proposed. The method uses the simplest configuration with co-propagating pump and signal waves. The possibility of polarization insensitive four-wave mixing is shown for a tensile quantum well. Polarization insensitivity can be obtained by the right detuning of the pump wavelength from the gain peak.     

Wavelength conversion up to 18 nm at 10 Gb/s by four-wave mixing in a semiconductor optical amplifier

We characterize the conversion bandwidth of a four-wave mixing semiconductor optical amplifier wavelength converter. Conversion of 10-Gb/s signals with bit-error-rate (BER) performance of <10/sup -9/ is demonstrated for wavelength down-shifts of up to 18 nm and upshifts of up to 10 nm.     

Picosecond optical sampling using four-wave mixing in fibre

An all-optical sampling system with 20 ps resolution realised by employing four-wave mixing in a fibre is demonstrated. Using only semiconductor laser sources, picosecond pulses are displayed on a microsecond time scale with a low speed receiver.<>