Use Of Four-wave Mixing Research Articles

Use of four-wave mixing for designing and simulating an all-optical AND logic gate in a photonic crystal semiconductor optical amplifier

A simple method has been proposed to use four-wave mixing to design and simulate the all-optical AND logic gate in a photonic crystal semiconductor optical amplifier (PC-SOA) that is integrated with an ideal optical bandpass filter. The preferred logical function could be carried out in the proposed scheme with no use of a continuous-wave signal. Nonlinearities including carrier depletion, carrier heating, and spectral hole burning have been considered in the presented simulations. Furthermore, for improvement of the AND logic gate performance, the impacts of the pattern effect of the signals propagating in the PC-SOA medium, the input signal bit rate effects, and gain recovery have been extensively investigated. The findings demonstrated that the optimal output signal featuring 3-fJ energy and 2-mA injection current could be achieved at a bit rate of 50 Gbps.

Phase detection through four-wave mixing in an optical fiber

A scheme for detecting the phase of an incoming optical signal is systematically optimized and demonstrated experimentally. It makes use of four-wave mixing in a highly nonlinear fiber but differs from a phase-sensitive amplifier by its focus on phase detection, rather than on phase-dependent noise reduction. This experimental setup combines the signal with its phase-conjugated idler at the same frequency, before sending the combination to a photodetector. Experimental results show that the ratio of maximum and minimum currents can exceed 1000 even at a relatively low pump power of 10 mW. The proposed scheme may be useful for detecting the signal phase in coherent communication systems without the need of heterodyne detection.

All Optical Signal-Processing Techniques Utilizing Four Wave Mixing

Four Wave Mixing (FWM) based optical signal-processing techniques are reviewed. The use of FWM in arithmetical operation like subtraction, wavelength conversion and pattern recognition are three key parts discussed in this paper after a brief introduction on FWM and its comparison with other nonlinear mixings. Two different approaches to achieve correlation are discussed, as well as a novel technique to realize all optical subtraction of two optical signals.

Label swapping and packet transmission of DPSK-labeled PPM signal in optical label switching

A label swapping scheme of an optical labeled signal with differential phase shift keying (DPSK) for label at 2.5 Gb/s and pulse position modulation (PPM) for payload at 40 Gb/s is demonstrated by simulation. Power penalties of ?1.8 and ?0.8 dB are achieved for both the payload and label over 80-km single mode fiber (SMF) transmission. This labeling scheme allows the use of four-wave mixing (FWM) in semiconductor optical amplifier (SOA) to perform label erasure, with advantages of transparence for bit rate, high processing rate, simple architecture, and low cost. Label swapping is demonstrated with appropriate penalties of ?3.5 and 0.8 dB for PPM payload and new DPSK label, respectively. To further prove the effectiveness of the proposed scheme, label swapping in the case of using 10-Gb/s DPSK label is also investigated with the power penalties of 6 and 2 dB for PPM payload and new DPSK label.

Bidirectional Transmission with a Single Fiber using FWM for WDM-PON

This paper investigates bidirectional transmission using four wave mixing (FWM) for wavelength division multiplex passive optical network (WDM-PON) applications. A semiconductor optical amplifier (SOA) is considered to generate FWM. A use of FWM makes it possible to convert a downstream data wavelength to a different wavelength, which is used for upstream transmission. The wavelength generated by FWM can realize bidirectional transmission with a single fiber. We assume intensity modulation (IM) for both up- and down-transmission. Both an injection locked Fabry-Perot laser diode (FP-LD) transmitter and a transmitter with an external modulator are considered for upstream transmission. In both cases, an extinction ratio (Ex) of downstream signal light is very important for both sending and receiving properties and the Ex influences the bit error rate (BER) property. This paper clarifies the relationship between the Ex of FWM and the power penalty ΔP. This paper also clarify the Ex value of FWM as a function of input signal Ex using a model SOA theoretically. Fundamental transmission experiments, 10 Gbit/s downstream and 2.5 Gbit/ s upstream, using both types of transmitters confirmed the possibilities of the bidirectional transmission using FWM.

Applications of Highly-Nonlinear Chalcogenide Glass Devices Tailored for High-Speed All-Optical Signal Processing

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Ultrahigh nonlinear tapered fiber and planar rib Chalcogenide waveguides have been developed to enable high-speed all-optical signal processing in compact, low-loss optical devices through the use of four-wave mixing (FWM) and cross-phase modulation (XPM) via the ultra fast Kerr effect. Tapering a commercial <formula formulatype="inline"><tex> $\hbox{As}_{2}\hbox{Se}_{3}$</tex> </formula> fiber is shown to reduce its effective core area and enhance the Kerr nonlinearity thereby enabling XPM wavelength conversion of a 40 Gb/s signal in a shorter 16-cm length device that allows a broader wavelength tuning range due to its smaller net chromatic dispersion. Progress toward photonic chip-scale devices is shown by fabricating <formula formulatype="inline"> <tex>$\hbox{As}_{2}\hbox{S}_{3}$</tex></formula> planar rib waveguides exhibiting nonlinearity up to <formula formulatype="inline"><tex>$2080\, {\rm W}^{-1}\cdot \hbox{km}^{-1}$</tex></formula> and losses as low as 0.05 dB/cm. The material's high refractive index, ensuring more robust confinement of the optical mode, permits a more compact serpentine-shaped rib waveguide of 22.5 cm length on a 7-cm-size chip, which is successfully applied to broadband wavelength conversion of 40–80 Gb/s signals by XPM. A shorter 5-cm length planar waveguide proves most effective for all-optical time-division demultiplexing of a 160 Gb/s signal by FWM and analysis shows its length is near optimum for maximizing FWM in consideration of its dispersion and loss. </para>

Synthesis of optical standard frequencies in the S, C and L telecommunication bands by use of four-wave mixing in semiconductor optical amplifiers

The generation of standard reference frequencies close to the ITU channels is essential for the calibration and maintenance of DWDM systems. This work describes a method to synthesize frequency references in the range from 187.1 to 205.1 THz (1462–1602 nm). The method is based on the generation of four equispaced frequencies (by the process of four-wave mixing in a semiconductor amplifier) of which two are locked to absorption lines of the acetylene 12C 2H 2 (1511–1542 nm).

Simple techniques for highly efficient wavelength conversion with low polarization sensitivity by use of semiconductor optical amplifiers

Experimental investigations of two schemes for polarization-direction-insensitive spectral conversion by use of four-wave mixing in a semiconductor optical amplifier (SOA) are reported. One scheme that utilizes an SOA with a linearly polarized signal and a single copropagating circularly polarized pump is, as far as we are aware, the simplest such scheme that has been reported to date. A theoretical analysis of this novel scheme is also presented. Experimental investigations of that scheme are compared with measurements of the performance of a previously proposed scheme, which involves the use of a single SOA and two orthogonal counterpropagating pump beams. We observe that polarization-direction-insensitive conversion is far more efficient in the new scheme described here. Within the observed detuning range, the difference in efficiency between the two schemes is found to increase from 6 to 18 dB as the detuning is increased. The corresponding increase in the difference of the signal-to-background ratio between the two schemes is from approximately 2 to 16 dB.

Depositing light in a photonic stop gap by use of Kerr nonlinear microresonators.

We show theoretically that it is possible to trap light in a microresonator structure by use of four-wave mixing. The efficiency of the parametric process is substantially increased by the high group delay of light inside the structure. The energy that is trapped has a half-life of approximately 500 ps in the presence of both linear and nonlinear loss in the channel waveguides and resonators. We also demonstrate that the energy can be extracted from the cavity with a similar process.

Full geometry dependence of index contrast in photorefractive polymer composites.

Detailed analysis of the relationship between the experimental geometry and the holographic contrast in photorefractive polymers is important for applications, such as angle multiplexing in holographic data storage. In this paper the field dependent photogeneration efficiency is introduced into the complete reorientational model to provide a full account of the electric field and geometrical dependence of the index contrast. The interaction of a local grating and the photorefractive grating is also considered. A simplification for acute angles between writing beams is described. Experimental verification by use of four-wave mixing and transmission ellipsometry reveals an excellent agreement between theory and measurement.

Origin of frequency shift and temporal instability in photorefractive self-pumped phase conjugators

The physical origin of frequency shift and dynamic instability in a photorefractive self-pumped phase conjugator is analyzed by use of four-wave mixing and multi-four-wave mixing. We show that the frequency shift and the instability result from the requirement of the maximal energy transfer between the interacting beams. Two examples of numerical results in a cat self-pumped phase conjugator are given, which are in good agreement with previous experimental results. A simple method is proposed to change an unstable phase-conjugate output to a stable one.

Wavelength conversion by use of four-wave mixing in a novel optical loop configuration

A novel loop configuration for generation of four-wave mixing (FWM) and suppression of input pump wave, signal wave, and amplified spontaneous emission is proposed and experimentally demonstrated. The novel loop configuration is very simple and functions independently of the wavelengths of the pump and the signal waves. By use of the novel loop configuration, nonreturn-to-zero wavelength conversion at 10 Gbits/s is achieved. The FWM-to-pump ratio, the FWM-to-signal ratio, and the signal-to-noise ratio are improved by 17.9, 18.8, and 8.2 dB, respectively. A principle experiment of wavelength conversion of four simultaneous channels is demonstrated.

Transient optical modulation with a disperse-red-1–doped polymer film

Transient optical modulation properties of a disperse-red-1-doped polymer film are investigated by use of four-wave mixing with two-color light. Interesting behavior is observed for the transient modulation on variation of the two-color light intensities because of competition between the two mechanisms of one-photon (reorientation) and biphoton (isomerization) gratings. Positive and negative modulation as well as double-frequency modulation relative to blue-light input is observed in the experiment. The results may have applications in optical information processing.

Phase conjugation of a speckle-inhomogeneous beam by an Nd glass oscillator based on four-wave mixing with feedback

A study is reported of a system, making use of four-wave mixing with feedback (FWMF), for high-quality phase conjugation of speckle-inhomogeneous radiation. The system includes a hologram formed on the basis of nonlinearity of gain saturation. A theoretical analysis is made of selective capabilities of a 'short' hologram, whose length is less than the longitudinal correlation lengths of the 'write' waves used to form it. The statistical-average values of the parameters of modes in an FWMF cavity are determined. The experimental results obtained for a neodymium glass system show that the fidelity of phase conjugation of speckle beams with a divergence (5 — 25) θdiffr is 80%. The maximum energy of the phase-conjugated component is 0.35 J and the maximum energy reflection coefficient of an FWMF mirror is 20.

All-optical power-controlled switching in four-wave mixing

The use of four-wave mixing as an all-optical switching device is described. The switching process involves strong pump depletion and results from large-signal interactions. Interesting relationships among the input, the optical control, and the output signals and the parameters of the nonlinear medium are identified.

Phase conjugation by four-wave mixing in inhomogeneous plasmas

The effects of density, temperature, and velocity gradients on four-wave mixing (FWM) in a plasma are investigated. A fluid model is used in which the stimulated Brillouin terms are included, but pump depletion is neglected. The steady state phase conjugate reflectivity and signal transmission coefficients are calculated and discussed for both degenerate and resonant FWM. The substantial effects of inhomogeneity on the use of FWM as a plasma diagnostic are discussed.

Quantum statistics of four-wave mixing

Photon statistics in four-wave mixing are discussed, with particular attention to antibunching of photons, their subpoissonian behaviour and to squeezing, making use of the short-length approximation or the parametric approximation. All possibilities are found to generate these non-classical optical fields with the use of four-wave mixing and the obtained results are compared with those for optical parametric processes and non-degenerate hyper-Raman scattering.