Four-wave Mixing In Semiconductor Optical Amplifier Research Articles

A ROF system based on 18-tuple frequency millimeter wave generation using external modulator and SOA

In this paper, we have reported a radio-over-fiber (ROF) system with 18-tuple frequency optical millimeter-wave using external modulator and four-wave mixing (FWM) in semiconductor optical amplifier (SOA). Signal lightwave and pump with frequency interval of 6fRF are generated by adjusting the parameters of the Mach-Zehnder modulator (MZM). After FWM in SOA and filtering, 18-tuple frequency millimeter-wave signal is generated. Based on the proposed scheme, a 90 GHz optical millimeter-wave is generated only using 5 GHz RF by numerical simulation. The simulation results show that our proposed scheme can provide 20 km single-mode fiber (SMF) transmission. In addition, the impact of SOA’s current on the sideband ratio (SR) and the system performance are also studied.

Cost-efficient, polarization-insensitive and widely-tunable AOWC of OFDM signal based on FWM in SOA.

In this paper, we propose a cost-efficient, polarization-insensitive and widely-tunable wavelength conversion scheme for orthogonal frequency division multiplexing (OFDM) signal based on four-wave mixing (FWM) in semiconductor optical amplifier (SOA). In this scheme, electrical OFDM signal directly drives directly modulated laser (DML) to achieve intensity modulation, then the modulated signal lightwave and pump are coupled and injected into a polarization-diversity structure for performing FWM in SOA. The analytical results show that the proposed scheme is polarization-insensitive and has a wider conversion range compared with the parallel pump scheme and orthogonal pump scheme. We have also numerically demonstrated wavelength conversion of 16QAM-OFDM signal by employing the proposed scheme. The results can be agreed with the theoretical analyses. In addition, the impact of input optical power, line-width of external cavity laser (ECL) and injection current of SOA on the system performance are also studied.

Microwave Photonic Harmonic Down-Conversion Based on Cascaded Four-Wave Mixing in a Semiconductor Optical Amplifier

A reconfigurable and wideband photonic method is proposed for microwave photonic harmonic down-conversion based on cascaded four-wave mixing in a semiconductor optical amplifier (SOA). The cascaded four-wave mixing in SOA triggers high-order harmonics generation of local oscillator (LO) in the optical domain, and enables microwave down-conversion in the electrical domain with a low-frequency electrical LO. Compared with the conventional photonic method, ours allows microwave down-conversion operation for wide frequency range RF signal with a low-frequency electrical LO, and at the same time it avoids the requirement of complex phase control and heavy driving for the electrical LO. Moreover, it enables reconfigurable down-conversion with frequency tunability. In the demonstration, the 3~40 GHz RF signals are experimentally down-converted to IF signals below 2 GHz with a low-frequency electrical LO within the range of 5 GHz.

Polarization insensitive all-optical wavelength conversion of polarization multiplexed signals using co-polarized pumps.

We study and experimentally validate the vector theory of four-wave mixing (FWM) in semiconductor optical amplifiers (SOA). We use the vector theory of FWM to design a polarization insensitive all-optical wavelength converter, suitable for advanced modulation formats, using non-degenerate FWM in SOAs and parallelly polarized pumps. We demonstrate the wavelength conversion of polarization-multiplexed (PM)-QPSK, PM-16QAM and a Nyquist WDM super-channel modulated with PM-QPSK signals at a baud rate of 12.5 GBaud, with total data rates of 50 Gbps, 100 Gbps and 200 Gbps respectively.

All Optical Wavelength Conversion of Nyquist-WDM Superchannels Using FWM in SOAs

In this paper, the performance of all-optical wavelength conversion (WC) of Nyquist-WDM superchannels is investigated for future implementation in optical networks. We consider advanced modulation formats of DQPSK and 16-QAM for the subchannel modulation format achieving raw bit rates of 448 and 896 Gb/s, respectively. We demonstrate through simulations the WC of Nyquist-WDM superchannel using degenerate and nondegenerate four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). We consider the effects of raised cosine (RC) and root raised cosine (RRC) signal pulse shaping within the wavelength conversion process. We find that the performance of the converted superchannel is severely impaired by crosstalk due to cross-gain modulation of the pump by the superchannel. Optimum performance of the converted superchannel is achieved by setting the detuning between the continuous-wave pump and the central wavelength of the superchannel to be around 200 GHz and using pumps of double the gain saturation power of the SOA with 23 dB pump to signal power ratio.

Multichannel wavelength multicasting for two QPSK signals based on FWM in SOA

We experimentally demonstrate multichannel wavelength multicasting for two nonreturn-to-zero quadrature phase-shift keying (NRZ-QPSK) channels based on four-wave mixing (FWM) in semiconductor optical amplifier (SOA). Through the interaction with the two pumps in SOA, the input two 25 Gb/s NRZ-QPSK channels are successfully simultaneously multicast to five and two new wavelengths, respectively. All the multicast channels are with a power penalty less than 2.5 dB at a bit error rate (BER) of 10-3. A characterization of the system performance using conversion efficiency and BER as figures-of-merit in terms of pump and signal powers is also presented. The results indicate that the pump and signal powers can be optimized to eliminate the introduced deleterious nonlinear components. The wavelengths of the two NRZ-QPSK channels and the two pumps need to be specified to avoid the crosstalk induced by high-order FWM.

A wavelength conversion scheme based on SPM and FWM for distributed satellites system with multiple wavelength channels

Aiming at the characteristics of distributed satellites system that the information exchanging and wavelength conversion are frequent but the payload is limited, a wavelength conversion scheme based on the self-phase modulation (SPM) and the four-wave mixing (FWM) is put forward, which can substitute several pump lasers in case of multiple wavelength channels. By utilizing the SPM in high nonlinear fiber to broaden the spectrum of initial signal, a pre-conversion signal is obtained as the pump light for wavelength conversion through an offset filtering. Then the wavelength conversion is realized based on the FWM in semiconductor optical amplifier. The principle of the scheme is deduced theoretically, and the relationship between conversion properties and structural parameters is analyzed. The simulation results show that the scheme can improve the quality of signal to some extent when completing a wavelength conversion, the Q factor improvement can be of 3 dB at most, while the conversion efficiency can reach to 20 dB.

Gigahertz to terahertz tunable all-optical single-side-band microwave generation via semiconductor optical amplifier gain engineering

We propose and demonstrate a technique to generate low-noise broadly tunable single-side-band microwaves using cascaded semiconductor optical amplifiers (SOAs) using no RF bias. The proposed technique uses no RF components and is based on polarization-state controlled gain-induced four-wave mixing in SOAs. Microwave generation from 40 to 875 GHz with a line-width ~22 KHz is experimentally demonstrated.

Novel anti-jamming technique for OCDMA network through FWM in SOA based wavelength converter

In this paper, we propose a novel anti-jamming technique for optical code division multiple access (OCDMA) network through four wave mixing (FWM) in semiconductor optical amplifier (SOA) based wavelength converter. OCDMA signal can be easily jammed with high power jamming signal. It is shown that wavelength conversion through four wave mixing in SOA has improved capability of jamming resistance. It is observed that jammer has no effect on OCDMA network even at high jamming powers by using the proposed technique.

Wired/wireless access integrated RoF-PON with scalable generation of multi-frequency MMWs enabled by polarization multiplexed FWM in SOA

In this paper, we propose and demonstrate a novel integrated radio-over-fiber passive optical network (RoF-PON) system for both wired and wireless access. By utilizing the polarization multiplexed four-wave mixing (FWM) effect in a semiconductor optical amplifier (SOA), scalable generation of multi-frequency millimeter-waves (MMWs) can be provided so as to assist the configuration of multi-frequency wireless access for the wire/wireless access integrated ROF-PON system. In order to obtain a better performance, the polarization multiplexed FWM effect is investigated in detail. Simulation results successfully verify the feasibility of our proposed scheme.

All optical single module phase encoded half-adder and halfsubtractor exploiting four wave mixing in semiconductor optical amplifier

The development of all optical super fast arithmetic logic unit (ALU) is one of the most important requirement for construction of super fast all optical processor. All optical half-adder and half-subtractor have performed most of the essential functions of the arithmetic logic unit. Here in this paper the author has proposed a scheme of single module for phase encoded simultaneous operation of half-addition and half- subtraction for the same input bits using four wave mixing (FWM) in semiconductor optical amplifier (SOA). This type of single module for simultaneous operations using phase encoding based on the difference of phase with the reference signal one through FWM in SOA will gives fast response to accomplish the demand of super fast all optical processing. Keywords - ALU, FWM, SOA, half-adder and half-subtractor.

Multiple-frequency basestation RoF system based on polarization multiplexed FWM in SOA

An approach of multiple-frequency millimeter-wave (mm-wave) signal generation is proposed for radio-over-fiber (RoF) system with multiple-frequency basestations (MFBSs). Two groups of orthogonally polarized signals are injected into a semiconductor optical amplifier (SOA), and subsequently ten new different wavelengths are generated via four-wave mixing (FWM) effect. At each MFBS, different wavelengths are filtered out using demultiplexer and then input to a photodiode (PD) to generate the mm-wave signals with the frequencies from 52 GHz to 68 GHz at the interval of 2 GHz. Simulation results verify that the proposed multiple-frequency generation for MFBS RoF system can work properly.

Proposal for all-optical generation of multiple-frequency millimeter-wave signals for RoF system with multiple base stations using FWM in SOA

An approach for the multiple-frequency millimeter-wave (mm-wave) signals generation is proposed and demonstrated, specifically, which can be applied to a radio-over-fiber (RoF) system with multiple base stations (BSs). In this scheme, optical double sideband (ODSB) modulation is achieved using a Mach-Zehnder modulator (MZM) to generate the two-sideband signals. New frequencies of the optical signals are obtained by using four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). At the BSs, two different frequencies are achieved using a comb optical filter (COF), and which then input a photodiode (PD) to generate the mm-wave signals with the frequencies of 20, 40 or 60 GHz for different BSs, by mixing of these frequencies components. Experimental results verify that the proposed multiple-frequency mm-wave signals generation scheme for a RoF system with multiple base stations can work properly.

Experimental verification of the existence of optically induced carrier pulsations in SOAs

Experimental investigation of the role of interband effects in four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) is reported. Carrier density pulsations (CDP) in SOAs, caused by optical wave beating, are measured in the RF domain. This gives strong experimental confirmation of the link between CDP and wave mixing, as usually assumed in theory of FWM in SOAs. The dependence of CDP amplitude on bias current and optical power is also established.

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 0.40 ns 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 conversion for 10-Gb/s NRZ payload and 2.5-Gb/s OFDM label in optical-packet-switched network

Simultaneous wavelength conversion based on four-wave mixing (FWM) for 10-Gb/s NRZ payload and 2.5-Gb/s OFDM label signals in optical switching network is experimentally demonstrated. The dual-pump scheme based on FWM in semiconductor optical amplifier (SOA) is employed and simultaneous wavelength conversion for optical packet with one optical payload of 10-Gb/s non-return-to-zero (NRZ) on-off keying (OOK) signals and one optical label of 2.5-Gb/s OFDM signals are realized. The bit-error-rate performance is evaluated for both payload and label after wavelength conversion.

Transmission performance of 10-Gb/s DPSK WDM signals due to phase-error and four-wave mixing in SOAs

We present a complete dynamic model of semiconductor optical amplifiers (SOAs) including the inter-channel four-wave mixing (FWM). The model has been implemented using the time-dependent transfer matrix method (TMM) and applying the discretization scheme in both the spatial and spectral domains. In SOA-based wavelength division multiplexing transmission systems using 10-Gb/s differential phase shift keyed (DPSK) signals, the system performance due to the SOA-induced phase-error and the FWM effect has been analyzed. By the injection of a reservoir channel into SOAs, the transmission performance of non-return-to-zero (NRZ) DPSK signals can be improved through the phase-error reduction. Both the NRZ-DPSK and return-to-zero (RZ) DPSK signals are found to be suffered from the FWM-induced crosstalk. The overall nonlinear tolerance of RZ-DPSK is shown to be better than that of NRZ-DPSK.

Amplitude Regenerative Characteristics of RZ-DPSK Wavelength Converter Based on Four-Wave Mixing in SOA

We investigate the phase-preserving amplitude regenerative characteristics of the return-to-zero (RZ) differential-phase-shift-keying (DPSK) wavelength conversion based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). The Q-factor and the optical signal-to-noise ratio (OSNR) before and after conversion are experimentally obtained and analysed in different input noise power levels. In both the continuous-wave and synchronous clock pumping cases, we find that there is amplitude clamping in the FWM conversion due to the gain saturation of SOA, which can suppress the amplitude fluctuation of the converted DPSK signal before and after demodulation. We have achieved 2-dB Q penalty improvement in our experiment demonstration of 10Gbit/s RZ-DPSK signal with OSNR lower than 19dB.

Concatenation performance of optical packet switches that incorporate wavelength converters based on four-wave mixing in semiconductor optical amplifiers

Four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) has been acknowledged as a useful wavelength conversion technique especially due to its ability to convert sequences of ultra fast pulses but also simultaneously a number of wavelengths. An analysis is used to investigate the concatenation performance of optical packet switch that incorporate wavelength or waveband converters based on FWM in SOAs.

An all-optical XOR logic gate for high-speed RZ-DPSK signals by FWM in semiconductor optical amplifier

All-optical exclusive-OR (XOR) logic gate is a basic and crucial element for optical signal processing. We propose and demonstrate a novel high-speed all-optical XOR gate based on four-wave mixing (FWM) in a semiconductor optical amplifier, with optical return-to-zero differential phase-shift keying (RZ-DPSK) input signals. With this constant-envelope modulation format, the patterning effect-induced signal degradation in semiconductor optical amplifier (SOA) is alleviated. The proposed XOR gate can accommodate both two-input and three-input logic operations, which offer better flexibility for cascaded all-optical processing. Experimental demonstrations at 10- and 20-Gb/s verified the logic integrity of the proposed XOR gate. In addition, the XOR output tolerance against temporal misalignment among the data inputs is also experimentally investigated