Nonlinear Optical Wavelength Conversion Research Articles

Cascaded four-wave mixing all-optical wavelength converter based on highly nonlinear fiber deposited graphene oxide

The all-optical wavelength conversion using cascaded four-wave mixing (FWM) phenomena with graphene oxide (GO) and a highly nonlinear fiber (HNLF) device is demonstrated experimentally. GO has a strong third-order nonlinear effect and is an excellent nonlinear optical material for nonlinear optical wavelength conversion. The group velocity matching of pump and signal, HNLF, and GO amplification promote the cascaded nonlinear frequency mixing process. From the experimental and analytical results, the maximum spacing between signal and pump is 21 nm, and specifically, the order of cascaded FWM light increases from order 1 to order 2 with increasing GO, and the first-order FWM conversion efficiency increases to a maximum of −14.5 dB. To the best of our knowledge, this is the first time that cascaded FWM-based all-optical wavelength conversion in HNLF–GO with wide wavelength selectivity is investigated with combined pump and signal light. Our findings not only provide an effective method for achieving all-optical wavelength conversion in cascaded FWM but also offer the possibility of fabricating high-performance nonlinear optical devices.

All-fiber nonlinear optical wavelength conversion system from the C-band to the mid-infrared.

We demonstrate an all-fiber wavelength conversion system from the C-band to the wavelength range of 2.30-2.64 µm of the mid-infrared (MIR). A series of nonlinear processes is used to perform this spectral shift in excess of 80 THz; from optical pulses in the C-band, self-phase modulation spectral broadening and offset filtering generate probe pulses in the C- and L-band. In parallel to this, Raman-induced soliton self-frequency shift converts pulses from the C-band into pump pulses in the 2 µm wavelength band. The resulting synchronized probe and pump pulses interact via degenerate four-wave mixing to produce wavelength-converted idler pulses in the MIR. Silica fiber is used for nonlinear processes at wavelengths $ {\lt} 2\;{\unicode{x00B5}{\rm m}}$<2µm whereas chalcogenide glass is used for nonlinear processes at wavelengths $ {\ge} 2\;{\unicode{x00B5}{\rm m}}$≥2µm. This system is a major step toward the development of compact MIR optical sources generated from widespread pump lasers of the C-band.

Low-loss silicon core fibre platform for mid-infrared nonlinear photonics

Broadband mid-infrared light sources are highly desired for wide-ranging applications that span free-space communications to spectroscopy. In recent years, silicon has attracted great interest as a platform for nonlinear optical wavelength conversion in this region, owing to its low losses (linear and nonlinear) and high stability. However, most research in this area has made use of small core waveguides fabricated from silicon-on-insulator platforms, which suffer from high absorption losses of the use of silica cladding, limiting their ability to generate light beyond 3 µm. Here, we design and demonstrate a compact silicon core, silica-clad waveguide platform that has low losses across the entire silicon transparency window. The waveguides are fabricated from a silicon core fibre that is tapered to engineer mode properties to ensure efficient nonlinear propagation in the core with minimal interaction of the mid-infrared light with the cladding. These waveguides exhibit many of the benefits of fibre platforms, such as a high coupling efficiency and power handling capability, allowing for the generation of mid-infrared supercontinuum spectra with high brightness and coherence spanning almost two octaves (1.6–5.3 µm).

Composite‐Assisted Phase‐Matching: Efficient Wavelength Conversion in Nonlinear Optical Composite Materials Containing Metal Nanoparticles

AbstractA novel phase‐matching scheme which is based on the dispersion compensation in the nonlinear optical composite materials containing metal nanoparticles is proposed. Anomalous dispersion originating from the plasmon resonance in metal nanoparticles compensates the dispersion of the host nonlinear material, leading to the perfect phase‐matching and high efficiency of nonlinear optical wavelength conversion. The effectiveness of this approach is theoretically demonstrated, taking third‐order nonlinear processes such as the direct third‐harmonic generation and four‐wave mixing in ZnO composites containing silica‐core–silver‐shell nanoparticles as examples. The results show that with the proposed phase‐matching scheme, unprecedentedly high conversion efficiency can be obtained compared with preceding results in third‐order nonlinear optical solid‐state materials.

A High Dynamic Range and Spectrally Flat Terahertz Spectrometer Based on Optical Parametric Processes in LiNbO&lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;$_{3}$&lt;/tex&gt;&lt;/formula&gt;

A wideband, wavelength tunable, spectrally flat terahertz (THz) spectrometer with a dynamic range in excess of 70 dB was demonstrated. The emission of THz-wave was achieved using an injection-seeded THz parametric generator (is-TPG), and detection was achieved using nonlinear optical wavelength conversion, both in magnesium-oxide-doped lithium niobate crystal. This system has potential applications in non-destructive sensing and imaging of a wide variety of materials.

Chromatic Dispersion Compensation via Mid-span Spectral Inversion with Periodically Poled LiNbO3 Wavelength Converter at Low Pump Power

Mid-span spectral inversion (MSSI) has to utilize high optical pump power, for its operation principle is based on a nonlinear optical wavelength conversion. In this paper, a low pump-power operation of MSSI-based chromatic dispersion compensation (CDC) has been achieved successfully, for the first time to our knowledge, by introducing a noise pre-reduction scheme in cascaded wavelength conversions with periodically poled LiNbO3 waveguides at a relatively low operation temperature. As preliminary studies, phase-matching properties and operation-temperature dependence of the wavelength converter (WC) were characterized. The WC pumped at 1549 nm exhibited a wide conversion bandwidth of 59 nm covering the entire C-band and a conversion efficiency of –23.6 dB at 11 dBm pump power. CDC experiments were implemented with 2.5 and 10 Gb/s transmission systems over 100 km single-mode fiber. Although it is well-known that the signal distortion due to chromatic dispersion is not critical at a 2.5 Gb/s transmission, the clear recovery of eye patterns was identified. At 10 Gb/s transmission experiments, eye patterns were retrieved distinctly from seriously distorted ones, and notable improvements in bit-error rates were acquired at a low pump power of 14 dBm.

Nonlinear-optic wavelength conversion and signal processing devices using quasi-phase-matching waveguides

Nonlinear-optic wavelength conversion and signal processing devices using quasi-phase-matching waveguides

Periodically domain-inverted LiNbO3 for waveguide quasi-phase matched nonlinear optic wavelength conversion devices

The authors’ work on LiNbO3 waveguide quasi-phase matched nonlinear optic wavelength conversion devices is reviewed. The requirements of domain-inverted gratings for efficient wavelength conversions are shown by theoretical analysis of the device performances. The fabrication apparatus of the domain-inverted gratings is described, and it is shown that the fabricated gratings satisfy the requirements. A variety of LiNbO3 waveguide quasi-phase matched (QPM) wavelength conversion devices were fabricated and examined. Second-harmonic green/blue/ultraviolet light generation with normalized conversion efficiencies of ∼ 100%/W, third-harmonic generation by cascading second-harmonic generation and sum-frequency generation, and difference-frequency generation for wavelength conversion in infrared wavelength range are demonstrated.