Four-wave Mixing Wavelength Conversion Research Articles

Fully spectrum-sliced four-wave mixing wavelength conversion in a Semiconductor Optical Amplifier

Fully spectrum-sliced four-wave mixing wavelength conversion in a Semiconductor Optical Amplifier

Ultrahigh Efficiency Four-Wave Mixing Wavelength Conversion in Packaged Silica Microrod Resonator

Whispering-gallery-mode (WGM) resonator with high-quality factor ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> ) is a key platform for a wide range of fields including nonlinear optics, biosensing and quantum photonics. In this work, a packaged silica microrod resonator (PSMR) with ultrahigh- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\bf 9.0\times 10^{8}$</tex-math></inline-formula> is experimentally demonstrated. Ultrahigh four-wave mixing conversion efficiency of −8.6 dB at a pump power of 27 mW is achieved within this ultrahigh- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> PSMR. Furthermore, this PSMR shows high stability of resonant wavelength shift within 0.032 pm. This work suggests that the PSMR may be a promising platform for optical signal processing and quantum photonics.

Efficient four-wave mixing wavelength conversion in a hybrid silicon slot and polymer microring resonator.

We present a silicon slot microring resonator for efficient frequency conversion via four-wave mixing (FWM). The slot consists of a narrow silicon waveguide pair with a gap of 80 nm, which is filled with a nonlinear optical polymer. The group velocity dispersion for the microring is controlled by engineering the geometry of the slot structure. Because of the large buildup factor of the slot microring, an FWM conversion efficiency of -27.4 dB is achieved with an optical pump power of less than 1.0 mW. From the measured power dependence of FWM generation, a nonlinear refractive index coefficient of 1.31 × 10-17 m2 W-1 is obtained at a wavelength of 1562 nm. This work presents a hybrid silicon slot and polymer microring as a potential nonlinear device for applications in integrated photonic devices.

Ultra-low-power four-wave mixing wavelength conversion in high-Q chalcogenide microring resonators.

A compact Ge11.5As24Se64.5 chalcogenide microring resonator is fabricated with an intrinsic quality factor of 3.0×105 in the telecom band. By taking advantage of the strong nonlinearity and cavity enhancement, highly efficient wavelength conversion via four-wave mixing is demonstrated using a microring resonator. Conversion efficiency of -33.7dB is obtained by using an ultra-low pump power of 63.8 µW. This work shows that Ge11.5As24Se64.5 chalcogenide microring devices are promising for quantum photonics.

Optimization of four-wave mixing wavelength conversion in a quantum-dot semiconductor optical amplifier based on the genetic algorithm

A novel approach based on the artificial neural network (ANN) and the genetic algorithm (GA) is presented for optimization of four-wave mixing (FWM) wavelength conversion in a quantum dot semiconductor optical amplifier (QD-SOA). First of all, we propose a simple, accurate, and fast model based on the feedforward ANN for the characteristics of FWM in a QD-SOA. To train the ANN, we collect the required data from a numerical model. In this model, the efficiency of FWM is obtained numerically taken into account the effect of pump/probe and the occupation probability of energy levels by using the slice technique. Then, the optimal design of QD-SOA as the FWM wavelength converter is performed using the GA.

Silicon/silicon-rich nitride hybrid-core waveguide for nonlinear optics.

A silicon/silicon-rich nitride hybrid-core waveguide has been proposed and experimentally demonstrated for nonlinear applications to fill the gap between the pure silicon waveguide and the pure silicon nitride waveguide with respect to the nonlinear properties. The hybrid-core waveguide presented here leverages the advantages of the silicon and the silicon-rich nitride waveguide platforms, showing a large nonlinearity γ of 72 ± 5 W-1 m-1 for energy-efficient four-wave mixing wavelength conversion. At the same time, the drawbacks of the material platforms are dramatically mitigated, exhibiting a reduced two-photon absorption coefficient βTPA of 0.023 cm/GW resulting in an increased nonlinear figure-of-merit as large as 21.6. A four-wave-mixing conversion efficiency as large as -5.3 dB has been achieved with the promise to be larger than 0 dB. These findings are strong arguments supporting the silicon/silicon-rich nitride hybrid-core waveguide to be used for energy-efficient nonlinear photonic applications.

Four-wave mixing in Ar-filled hollow core bandgap photonic crystal fiber.

To study the four-wave mixing (FWM) effect and wavelength conversion in a hollow core bandgap photonic crystal fiber filled with Ar, we conducted an experiment using a femtosecond laser with the pulse width of 120fs, a repetition rate of 76MHz, and tunable central wavelength from 760 to 980nm. It is observed that new spectra are generated in both sides of the pump at a special wavelength, which can exactly satisfy the phase matching conditions of FWM. Combining experimental results with theoretical analysis, we find that the experimental phenomenon is mainly caused by FWM, and some other nonlinear phase effects, such as self-phase modulation, stimulated Raman scattering, and the soliton effect, have also occurred in this nonlinear process.

Temperature sensitivity of chromatic dispersion in nonlinear silica and heavy metal oxide glass photonic crystal fibers

In this paper we report on the examination of the temperature influence of the effective refractive index and on the dispersion characteristics in air-hole lattice photonic crystal fibers. We use an original method to measure the temperature influence on chromatic dispersion in an optical fiber, where both the thermal expansion of the fiber and its effective group refractive index are taken into account. We present the experimental and modeling results of dispersion characteristics for two types of non-linear fibers, a silica glass fiber and a soft glass fiber in the temperature range from 20°C to 420°C. We measured the zero dispersion wavelength shift of + 0.020 nm/°C for the fused silica fiber and + 0.045 nm/°C for the heavy metal oxide soft glass fiber. Experimental results are in agreement with numerical modeling. Finally, the influence of the temperature-induced change of the dispersion profile on nonlinear performance of the studied fiber structures is investigated numerically. Notable change of parametric gain maxima locations is observed even for small changes of the zero dispersion wavelength in relation to the pump laser wavelength in a four-wave mixing fiber-based wavelength conversion scenario.

Phase Conjugated and Transparent Wavelength Conversions of Nyquist 16-QAM Signals Employing a Single-Layer Graphene Coated Fiber Device.

We fabricate a nonlinear optical device based on a fiber pigtail cross-section coated with a single-layer graphene grown by chemical vapor deposition (CVD) method. Using the fabricated graphene-assisted nonlinear optical device and employing Nyquist 16-ary quadrature amplitude modulation (16-QAM) signal, we experimentally demonstrate phase conjugated wavelength conversion by degenerate four-wave mixing (FWM) and transparent wavelength conversion by non-degenerate FWM in graphene. We study the conversion efficiency as functions of the pump power and pump wavelength and evaluate the bit-error rate (BER) performance. We also compare the time-varying symbol sequence for graphene-assisted phase conjugated and transparent wavelength conversions of Nyquist 16-QAM signal.

Recent Advances in Graphene-Assisted Nonlinear Optical Signal Processing

Possessing a variety of remarkable optical, electronic, and mechanical properties, graphene has emerged as an attractive material for a myriad of optoelectronic applications. The wonderful optical properties of graphene afford multiple functions of graphene based polarizers, modulators, transistors, and photodetectors. So far, the main focus has been on graphene based photonics and optoelectronics devices. Due to the linear band structure allowing interband optical transitions at all photon energies, graphene has remarkably large third-order optical susceptibilityχ(3), which is only weakly dependent on the wavelength in the near-infrared frequency range. The graphene-assisted four-wave mixing (FWM) based wavelength conversions have been experimentally demonstrated. So, we believe that the potential applications of graphene also lie in nonlinear optical signal processing, where the combination of its unique largeχ(3)nonlinearities and dispersionless over the wavelength can be fully exploited. In this review article, we give a brief overview of our recent progress in graphene-assisted nonlinear optical device and their applications, including degenerate FWM based wavelength conversion of quadrature phase-shift keying (QPSK) signal, phase conjugated wavelength conversion by degenerate FWM and transparent wavelength conversion by nondegenerate FWM, two-input and three-input high-base optical computing, and high-speed gate-tunable terahertz coherent perfect absorption (CPA) using a split-ring graphene.

All-optical multi-channel wavelength conversion of Nyquist 16 QAM signal using a silicon waveguide.

We experimentally demonstrate on-chip all-optical multi-channel wavelength conversion of Nyquist 16 ary quadrature amplitude modulation (16 QAM) signal in a silicon waveguide. The measured optical signal-to-noise ratio (OSNR) penalties of wavelength conversion are ∼2 dB. The observed constellations of converted idlers indicate favorable performance of silicon-waveguide-based multi-channel wavelength conversion. We also experimentally study and compare the phase-conjugated wavelength conversion by degenerate four-wave mixing (FWM) and transparent wavelength conversion by non-degenerate FWM in the silicon waveguide.

Low-power continuous-wave four-wave mixing wavelength conversion in AlGaAs-nanowaveguide microresonators.

We experimentally demonstrate enhanced wavelength conversion in a Q∼7500 deeply etched AlGaAs-nanowaveguide microresonator via degenerate continuous-wave four-wave mixing with a pump power of 24mW. The maximum conversion efficiency is -43 dB and accounts for 12dB enhancement compared to that of a straight nanowaveguide. The experimental results and theoretical predictions agree very well and show optimized conversion efficiency of -15 dB. This work represents a step toward realizing a fully integrated optical devices for generating new optical frequencies.

All-optical manipulation of non-degenerate FWM conversion bandwidth by gain-transparent SBS

We demonstrate all-optical manipulation of non-degenerate four-wave mixing (FWM) wavelength conversion bandwidth based on phase-matching control through gain-transparent stimulated Brillouin scattering (SBS). A 3-dB bandwidth of 26nm is achieved when the conversion efficiency is maximized, corresponding to 44% increase from the original value. The bandwidth can also be shrunk to a minimum of 15nm. The spectral dependence of conversion efficiency can potentially be synthesized randomly, leading to a large tunability in the bandwidth. The performance in bandwidth manipulation is also evaluated in the wavelength conversion of 10Gbit/s non-return-to-zero (NRZ) on-off-keying (OOK) signal.

All-incoherent wavelength conversion in highly nonlinear fiber using four-wave mixing

This work describes efficient and polarization insensitive, all-incoherent four-wave mixing wavelength conversion achieved within a short length of highly nonlinear fiber medium, created by using both spectrally sliced pump and probe channels from a single-amplified spontaneous emission source coupled to two narrowband Fiber Bragg grating (FBG) filters. This simple and cost-effective scheme is capable of generating a down-converted probe channel across a 17.2-nm wavelength span, while still maintaining a high conversion efficiency of around −22 dB and an optical-signal-to-noise ratio of ∼21 dB. The effects of pump power, FBG detuning, and polarization are also reported.

Extended tunable optical delay using gain-transparent stimulated Brillouin scattering control in four-wave-mixing wavelength conversion

We propose and experimentally demonstrate an extended range of tunable optical delay obtained from four-wave mixing wavelength conversion and dispersion. The conversion bandwidth and the maximum delay are enlarged through dynamic control of the optical phase by gain-transparent stimulated Brillouin scattering. The delay range is increased by 37%. Bit-error-rate measurements show a maximum power penalty of 2.0 dB with reference to back-to-back performance. The technique can be applied to different configurations of tunable delay lines constructed with a fiber parametric process and dispersion.

Dynamic Control of Phase Matching in Four-Wave Mixing Wavelength Conversion of Amplitude- and Phase- Modulated Signals

We propose and experimentally demonstrate dynamic control of phase-matching in fiber-based four-wave mixing (FWM) for wavelength conversion of communication signals. By introducing self-compensation of optical gain/loss with stimulated Brillouin scattering (SBS) pump and Stokes waves, the FWM phase-matching condition and hence the conversion efficiency (CE) can be flexibly controlled. The phase difference between the interplaying fields is manipulated by modifying the refractive index through SBS without disturbing the initial parameters of the FWM process. The scheme is first applied to wavelength conversion of 10 Gbit/s non-return-to-zero (NRZ) on-off-keying (OOK) signal. Its performance on phase-transparent wavelength conversion is subsequently examined using 10 Gbit/s NRZ differential-phase-shift-keying (DPSK) signal. Eye diagrams, FWM spectra and bit-error rate (BER) performances for the converted signals without SBS, with gain-transparent SBS for maximum CE and for minimum CE are analyzed. In the OOK/DPSK wavelength conversion with gain-transparent SBS, the CE has been reduced by 10.7/11.4 dB at a signal-pump spectral spacing of 1.9/1.94 nm; while it has been enhanced by 8.8/7.4 dB at a signal-pump spectral spacing of 4.1/4.07 nm. The pronounced enhancement of the CE at large signal-pump spectral spacing results in enlargement of the 3-dB FWM conversion bandwidth. Limitations in the extent of bandwidth enlargement and noise performance are discussed. Potential use of the scheme in other applications is also described.

High‐Optical‐Quality Blends of Anionic Polymethine Salts and Polycarbonate with Enhanced Third‐Order Non‐linearities for Silicon‐Organic Hybrid Devices

A series of anionic polymethine dyes with different aromatic counterions are prepared to improve their compatibility as guests in an amorphous polycarbonate host. When they are used as the cladding material for silicon hybrid slot waveguides, four-wave mixing wavelength conversion and two-photon absorption-based optical-power modulation are observed. Such guest-host materials may be attractive candidates for all-optical signal-processing applications.

Widely Tunable Polarization-Insensitive Nondegenerate Four-Wave Mixing Wavelength Conversion for DPSK Signal

We demonstrate all-optical wavelength conversion for return-to-zero differential phase-shift keying (RZ-DPSK) signal by dual-pump four-wave mixing in a highly nonlinear photonic crystal fiber. By exploiting the residual birefringence in the fiber, the polarization of the first pump can be adjusted to achieve polarization-insensitive operation. The wavelength of the second pump is free to tune to broaden the conversion bandwidth. Open eyes of the converted signals are obtained for polarization-scrambled 10-Gb/s RZ-DPSK signal over a down-conversion bandwidth of 27 nm. Bit-error measurement shows a maximum power penalty of 4.5 dB at the error-free detection level.

Frequency conversion over two-thirds of an octave in silicon nanowaveguides

We demonstrate ultrabroad-bandwidth low-power frequency conversion of continuous-wave light in a dispersion engineered silicon nanowaveguide via four-wave mixing. Our process produces continuously tunable four-wave mixing wavelength conversion over two-thirds of an octave from 1241-nm to 2078-nm wavelength light with a pump wavelength in the telecommunications C-band.

Experimental study of slow light based on four-wave mixing wavelength conversion and dispersion in optical fibers

Slow light based on four-wave mixing (FWM) wavelength conversion and dispersion is experimentally studied. The FWM bandwidth of the highly nonlinear fiber is measured to be 40 nm, which is also the slow light tunable bandwidth. A 34 ns delay of 500 MHz sine signal is achieved in standard single mode fiber, and 198 ns delay of short pulses with 100 ps width is achieved in dispersion compensation fiber (DCF). An advancement of 209 ns for the 100 ps short pulses is also achieved in the DCF. The method to increase the slow light delay is discussed, and large delay up to microseconds is expected when wideband FWM wavelength conversion and large dispersion fibers are used. The expected large delay will help us realize high efficiency fiber delay lines and all-fiber buffers.