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     

Analysis of basic four-wave mixing characteristics in asemiconductor optical amplifier by the finite-difference beampropagation method

We have numerically analyzed nondegenerate four-wave mixing (FWM) among short optical pulses in a semiconductor optical amplifier (SOA) by the finite-difference beam propagation method (FD-BPM). We used the nonlinear propagation equation taking into account gain spectrum dynamic gain saturation which depends on carrier depression, carrier heating, and spectral hole-burning, group velocity dispersion, self-phase modulation, and two-photon absorption. To analyze FWM in an SOA, the evolution in time and spectral domain of two input optical pulses with different frequencies during propagation was calculated. From this simulation, it has become clear that the method me used here is a very useful technique for simulating FWM characteristics in SOA's. We also found that the wavelength dependence of the gain is crucial if the detuning is larger than 1 THz     

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.     

160-Gb/s polarization insensitive all-optical demultiplexing usinga gain-transparent ultrafast nonlinear interferometer (GT-UNI)

We report on a polarization-insensitive all-optical demultiplexer based on gain-transparent operation of a semiconductor optical amplifier in an ultrafast nonlinear interferometer (GT-UNI) using polarization diversity. Error-free demultiplexing from 160 to 10 Gb/s is demonstrated     

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.<>     

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.     

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.     

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     

160-Gb/s optical networking: a prospective techno-economical analysis

This paper reports on a network dimensioning analysis of N /spl times/ 160-Gb/s wavelength-division-multiplexed (WDM) networks based on the optical time-division-multiplexing (OTDM) technique. The need for different transmission and networking functions based on innovative circuit-switched scenarios for optical core networks is quantified, and the economical interest of such high-wavelength channel bit rates in the chosen scenarios is evaluated.     

300-Gb/s eye-diagram measurement by optical sampling usingfiber-based parametric amplification

In this letter, we report on up to 300-Gb/s real-time all-fiber-based optical eye-diagram measurements with 1.6-ps temporal resolution and 5-Hz refresh rate by all-optical sampling using parametric amplification in a short (50 m) highly nonlinear fiber. This represents, to the best of our knowledge, the highest bit-rate eye-diagram measurement so far, as well as the first demonstration of a fiber-based eye analyzer. The sensitivity and operational optical bandwidth is comparable to previously reported state-of-the-art nonlinear crystal-based sampling systems. We believe our results show that fiber-based optical sampling is indeed a potential candidate for characterization of future ultrahigh bit-rate optical communication systems     

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     

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.     

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     

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.     

Long-haul high-speed optical communication systems using asemiconductor laser amplifier

High-speed long-haul systems using semiconductor laser amplifiers, which eliminate the need for high-speed electronics in repeaters and are transparent to the transmission speed are considered for application in undersea high-speed transmission systems. The potential of laser-amplifier-repeated transmission systems has been explored by transmission experiments, showing that a high-speed system above 2 Gb is possible by filtering out the spontaneous emission power of the laser amplifier. A theoretical estimation of SNR degradation due to noise accumulation of chained laser amplifiers shows that systems are possible, using 30 to 40 laser amplifier repeaters, if narrow-bandwidth optical filters are used     

Polarization-independent all-optical clock division using asemiconductor optical amplifier/grating filter switch

We propose and experimentally demonstrate, for the first time to our knowledge, polarization-independent all-optical clock division (CD) of an optical pulse train at 2.88 GHz. This is achieved using a semiconductor optical amplifier (SOA)/grating filter switch, where the SOA acts as a spectral shifter by a self phase modulation and the grating filter acts as a spectral shutter. The proposed scheme is very insensitive to the polarization of input pulses and requires very low switching energy (~102 fJ). After the all-optical CD operation, we have obtained the output pulse train at 1.44 GHz, which is half the input repetition rate, with high extinction ratio (>20 dB)