Four-wave Mixing Research Articles

Topologically-protected four-wave mixing enhanced by tailoring topological edge states

Laser pulse compression serves as a pivotal technique in nonlinear optics and light-matter interactions. Traditional methods, including Q-switching, mode-locking techniques, and chirped pulse amplification, are employed to generate high-intensity fields. However, these methods pose challenges when applied to topological lasers. In this study, we explore the pulse compression technique for topological edge states (TESs). Our findings reveal a significant correlation between the pulse width of TESs and their group velocity. Though factors such as nonlinear TES dispersion, disorders, and edge bending also affect pulse width, their impacts are comparatively less pronounced compared to that of group velocity. Through the customization of TES’s group velocity, we demonstrate a remarkable enhancement of four-wave mixing, showcasing it as a prime example of a nonlinear processing technique. Importantly, our approach promises seamless integration into topological laser systems, ensuring optimal performance with zero energy transfer loss and introducing a flexible dimension and robustness to topological nonlinear optical devices.

In situ characterization of two unknown ultrashort laser pulses using four-wave mixing in gas

In situ characterization of two unknown ultrashort laser pulses using four-wave mixing in gas

Unlocking multidimensional optical multicasting based on multi-mode PIN silicon waveguides

Multidimensional optical multicasting can increase the number of multicast optical channels and enhance spectrum utilization, which is crucial for future high-capacity optical networks and high-performance optical computing. However, simultaneously multicasting more channels results in higher energy density, which increases nonlinear loss within the waveguide and hinders practical applications. In this study, we introduce a reverse-biased PIN junction in the multi-mode waveguide to reduce nonlinear loss. Leveraging the multi-mode PIN silicon waveguide, we experimentally demonstrate a multidimensional multicasting strategy to simultaneously multicast an 80 Gb/s QPSK signal across 14 channels in both modes and wavelengths. Due to the PIN waveguide, the output power of the converted light after four-wave mixing (FWM) in three modes, TE0, TE1, and TE2, can be increased by 13 dB, 11.7 dB, and 7.7 dB, respectively. Furthermore, the 80 Gb/s QPSK signal can be multicast in three modes and from one wavelength channel to nine, seven, and two wavelength channels, respectively. All channels demonstrate clear constellation diagrams and error-free performance (biterrorrate<3.8×10−3). This demonstration provides a viable solution for multicasting in future mode and wavelength hybrid multiplexing optical networks, while also enhancing the capabilities of high-speed optical computing.

USING POWER MANAGEMENT AND DELAY MECHANISM IMPROVE THE PERFORMANCE OF OPTICAL FIBRE COMMUNICATION SYSTEM BY REDUCING FOUR WAVE MIXING

"This study examines the impact of four-wave mixing (FWM) on the performance of single-mode fibers (SMF). Using Optsim simulation software, a dispersion-compensating fiber (DCF) was implemented with varying dispersion and pulse intervals to analyze FWM behavior. The results show improved performance when power management techniques and time-domain delays are applied. The system's performance was evaluated using Q-factor and bit error rate (BER) metrics. "The system's performance was evaluated using Q-factor and bit error rate (BER) metrics."

Self-healing of orbital angular momentum in bright twin light beams generated via four-wave mixing

Self-healing of orbital angular momentum in bright twin light beams generated via four-wave mixing

Efficient generation of multi-order Raman radiation in aqueous solutions derived from -CH2 and -NH2 vibrations via cascaded four-wave mixing and Stokes processes

Efficient generation of multi-order Raman radiation in aqueous solutions derived from -CH2 and -NH2 vibrations via cascaded four-wave mixing and Stokes processes

Polarization state tomography of Stokes–anti-Stokes photon pairs from degenerate four-wave mixing in diamond

Polarization state tomography of Stokes–anti-Stokes photon pairs from degenerate four-wave mixing in diamond

Optimizing spectral phase transfer in four-wave mixing with gas-filled capillaries

Four-wave mixing (FWM) in gas-filled hollow-core capillaries, a nonlinear optical process that mixes signal and pump photon frequencies to generate idler frequency photons, offers a method for precise spectral phase transfer from signal to idler at ultrashort timescales and extreme powers. However, this regime is challenged by competing linear and nonlinear dynamics, leading to significant trade-offs between spectral phase transfer and conversion efficiency. Our computational investigation focuses on the upconversion of femtosecond pulses from the infrared (IR) to the ultraviolet (UV), a range notoriously difficult to manipulate. We explore an intermediate energy regime that strikes an optimal balance between FWM-mediated phase-transfer fidelity and nonlinear conversion efficiency. By adjusting the energy ratios and spectral phase profiles of the input signal, we achieve conversion efficiencies of approximately 5-15% while maintaining an effective quasi-linear spectral phase transfer. These findings will contribute to establishing first-principles and scaling laws essential for applications such as high-precision imaging, spectroscopy, quantum transduction, and distributed entangled interconnects, facilitating advanced control of ultrafast photonic and electronic wavepackets in quantum materials with unprecedented spatial and temporal precision.

Strategic modal management for enhanced stimulated Raman scattering in optical fibers

Raman fiber lasers have attracted significant attention for their unique ability to generate high-power output at specific wavelengths. Theoretically, the quantum loss associated with the nonlinear Stokes frequency shift in Raman scattering is lower than that from energy level transitions in conventional ytterbium-doped lasers, suggesting that Raman lasers should achieve higher conversion efficiencies. However, in practice, the efficiency of high-power Raman lasers often fails to reach these theoretical limits, with power scaling being impeded by 2 nd order Raman effects. In this article, we delve into the dynamics of stimulated Raman scattering within few-mode fibers, offering an in-depth analysis of the underlying physical mechanisms from multiple perspectives. Our research combines theoretical analysis with experimental research, covering the frequency domain, spatial domain, and nonlinear behavior. The experimental findings indicate that strategically increasing the proportion of higher-order modes in the injected light can enhance the conversion efficiency of the Raman process and effectively suppress higher-order Raman and four-wave mixing nonlinear processes. This study provides profound theoretical insights and practical guidance, contributing significantly to the ongoing development and optimization of Raman laser technology.

Optimizing four-wave mixing in Rydberg atoms for microwave-optical conversion

Optimizing four-wave mixing in Rydberg atoms for microwave-optical conversion

Wavelength multicasting quantum clock synchronization network

Quantum clock synchronization (QCS) can measure out the high-precision clock difference among distant users, which breaks through the standard quantum limit by employing the properties of quantum entanglement. Currently, the wavelength division multiplexed QCS network has been demonstrated with a spontaneous parametric down-conversion entangled photon source. In this paper, we propose a more efficient QCS network scheme with the wavelength multicasting entangled photon source, which can decrease at least 25% of wavelength channel consumption under the identical network scale. Afterwards, a four node QCS network is demonstrated, where the wavelength multicasting entangled photon source is utilized with dual-pumped four-wave mixing silicon chip. The experimental results show that the measured time deviation is 3.4 ps with an average time of 640 s via the multiple fiber links of more than 10 km.

Numerical Investigation of Raman-Assisted Four-Wave Mixing in Tapered Fiber Raman Fiber Amplifier

The generation of unwanted higher-order Raman effects is the main factor restricting the power scaling of Raman fiber amplifiers (RFAs). This phenomenon arises from an interplay of physical processes, including stimulated Raman scattering (SRS), four-wave mixing (FWM), and the intricate temporal and spectral dynamics. Tapered fibers have demonstrated excellent nonlinear effects suppression characteristics due to the varying core diameter along the fiber, which is widely used in ytterbium-doped fiber lasers. In this paper, a comprehensive numerical investigation is conducted on the core-pumping tapered fiber RFAs considering Raman-assisted FWM. The higher-order Raman power in the tapered fiber is always kept at a low level, showing a weak Raman-assisted FWM effect. A numerical investigation is conducted to study the impact of the tapering ratio, the lengths of the thin part, tapered region, and thick part on the higher-order Raman threshold of RFAs. Furthermore, the impact of phase mismatch variations caused by changes in the seed wavelength, on the output signal power and nonlinear effects is analyzed. This paper presents, for the first time, a study on core-pumped RFAs using tapered fibers, providing a novel perspective on enhancing the power of RFAs.

Heralded pure single-photon sources using nanophotonic waveguides with quadratic and cubic nonlinearities

This paper presents, to our knowledge, a new approach in developing integrated pure heralded single-photon sources based on the interplay between the spontaneous four-wave mixing and sum-frequency generation parametric processes. We introduce a comprehensive quantum model to exploit this interplay in AlGaAs and LiNbO3 nanophotonic waveguides. The developed model is used to assess the performance of the sources based on the photon-pair generation and the associated spectral purity. We find that this approach can remarkably improve the spectral purity of low-pure generated photon pairs, relaxing the restrictions on the structure design and the used pump wavelength. In addition, it overcomes the current hurdles in implementing on-chip photon detectors operating at room temperature, paving the way for advanced applications in integrated quantum photonics and information processing.

Selective conversion of CO2 to CO using blue TiO2 with an r-GO shell and quantitative measurement of excited electrons with four-wave mixing microspectroscopy

The conversion of CO2 into hydrocarbon or syngas (CO) using sunlight can address numerous current environmental issues and future challenges in the energy domain. Although numerous visible light-responsive photocatalysts have been reported, the quantum yield remains limited. Furthermore, analytical tools are yet to be established for quantitatively monitoring the amount of excited electrons, which play a critical role in catalytic reactions. The results of this study revealed that the presence of a reduced graphene oxide (r-GO) shell on blue-TiO2 (b-TiO2) considerably improves the photocatalytic performance in selectively converting CO2 into CO under visible light. The formation of the r-GO shell on b-TiO2 narrowed the b-TiO2 bandgap. Moreover, the r-GO shell increased the absorption of visible light and facilitated electron transfer, resulting in approximately eight times the CO yield from b-TiO2@r-GO compared to that of TiO2. The presence of the r-GO shell improved the photocatalytic stability of b-TiO2. Furthermore, four-wave mixing microspectroscopy was performed to analyze the amount of excited electrons. The results of microscopy revealed the amount of excited electrons in b-TiO2@r-GO was approximately 35 times that of TiO2. These results not only proposed a strategy for increasing the stability and efficiency of TiO2-based photocatalysts but also are useful for evaluating the improvement of photocatalyst materials.

Angled fiber-coupled MgF[formula omitted] microcavities for nonlinear optics in 1.5 and [formula omitted] bands

A versatile angled fiber coupling platform for magnesium fluoride whispering gallery mode resonators is used to investigate nonlinear frequency conversion across 1.5 and 2 μm bands. We characterize MgF2 microcavities of varying sizes (4.3 mm, 1.9 mm, and 0.73 mm in diameter), achieving quality factors up to 2×109 at 1.55μm and 5×108 at 1.94μm. In the telecom regime, we observe rich nonlinear phenomena including Kerr comb generation, Brillouin lasing, and Raman lasing. Extending to the 2 μm band, we demonstrate four-wave mixing in a sub-millimeter cavity, highlighting the platform’s potential for the 2 μm band mid-infrared nonlinear optics.

Extracting doubly excited state lifetimes in helium directly in the time domain with attosecond noncollinear four-wave-mixing spectroscopy

The helium atom, with one nucleus and two electrons, is a prototypical system to study quantum many-body dynamics. Doubly excited states, or quantum states in which both electrons are excited by one photon, showcase electronic-correlation mediated effects. In this paper, the natural lifetimes of the doubly excited 1Po2snp Rydberg series and the 1Se2p2 dark state in helium in the 60–65 eV region are measured directly in the time domain with extreme-ultraviolet/near-infrared noncollinear attosecond four-wave-mixing (FWM) spectroscopy. The measured lifetimes agree with lifetimes deduced from spectral linewidths and theoretical predictions, and the roles of specific decay mechanisms are considered. While complex spectral line shapes in the form of Fano resonances are common in absorption spectroscopy of autoionizing states, the background-free and thus homodyned character of noncollinear FWM results exclusively in Lorentzian spectral features in the absence of strong-field effects. The onset of strong-field effects that would affect the extraction of accurate natural lifetimes in helium by FWM is determined to be approximately 0.3 Rabi cycles. This study provides a systematic understanding of the FWM parameters necessary to enable accurate lifetime extractions, which can be utilized in more complex quantum systems in the future. Published by the American Physical Society 2024

Turning four-wave mixing on and off in elliptically birefringent fibers via narrow frequency detuning.

Controlling four-wave mixing (FWM) is vital for several applications, including fiber optical communication, optical signal processing, optical amplification, and frequency generation. This paper presents a novel, to our knowledge, approach to control unidirectional FWM in elliptically birefringent fibers. By leveraging the frequency-dependent polarization eigenmodes of these fibers and detuning the optical frequency of one of the pump fields by a few megahertz, we can turn the FWM interaction on and off, thus controlling the generation of signal and idler fields. Moreover, this approach allows us to turn off the FWM interaction at any desired frequency, enabling all-optical switching and narrowband filtering applications.

Tunable silicon integrated quantum light source with on-chip FSR-free filters.

In this work, we design and fabricate a telecom band quantum light source (QLS) on a silicon photonic chip, which integrates a piece of a long silicon waveguide as the nonlinear medium for spontaneous four-wave mixing (SFWM) and five narrow FSR-free bandpass filters based on a grating-assisted contra-directional coupler (GACDC). Two optical filtering functions of the silicon integrated QLS have been demonstrated. First, the QLS supports two tunable outputs of photon pair generations by four GACDC filters. A wavelength tunable range of 6 nm is demonstrated. Second, one GACDC bandpass filter is designed as an on-chip pump filter before the silicon waveguide. The performances of the QLSs with and without the on-chip pump filter are measured and compared. It shows that the on-chip pump filter has the effect to enhance the performance of the QLS by suppressing the Raman noise photons generated when a pump light propagated in optical fibers before it is injected into the chip. These results show that FSR-free filters would play important roles in developing silicon integrated QLSs.

On‐chip dual‐mode all‐optical multifunctional logic unit based on multimode FWMs

AbstractAn on‐chip dual‐mode all‐optical multifunctional logic operation unit including four AND and two OR logic gates is proposed and experimentally demonstrated. It is realized using multiple intra‐mode four‐wave mixing (FWM) processes in a multimode silicon waveguide for 2 × 10 Gbit/s non‐return‐to‐zero on–off‐keying (NRZ‐OOK) mode‐division multiplexing signals. The AND logic operation is realized via the non‐degenerate FWM processes, and the OR logic operation is realized by overlapping the two degenerate FWM idlers in frequency domain via appropriately selecting the dual‐mode pump wavelength. The two OR and four AND logic sequences are verified with NRZ‐OOK sequences for both TE0 and TE1 modes.

Frequency-Modulated Continuous-Wave Laser Source Based on Four-Wave Mixing Process in a Silicon Integrated Waveguide Doped With Reverse-Biased P-i-N Junction

Frequency-Modulated Continuous-Wave Laser Source Based on Four-Wave Mixing Process in a Silicon Integrated Waveguide Doped With Reverse-Biased P-i-N Junction