This is a list of reviewers who served JNP in 2018.

This guest editorial introduces the Special Section Guest Editorial: Optical Manipulation and Structured Materials

By modulating two cavity solitons (CSs) locally, in a driven vertical cavity surface emitting laser above threshold, we forced them to oscillate sinusoidally in time. It is illustrated that the amplitude of modulation of two CSs plays an important role in their synchronization. We show that the oscillations of two CSs can be synchronized only when the interaction of them is highly nonsymmetrical and the difference of the modulation frequencies is at most of the order of 1 GHz.

Invoking Maxwell’s classical electrodynamics in conjunction with expressions for the electromagnetic (EM) energy, momentum, force, and torque, we use a few simple examples to demonstrate the nature of linear and angular momentum exchange between a wave-packet and a small spherical particle. The linear and angular momenta of the EM field, when absorbed by the particle, will be seen to elicit different responses from the particle.

Temperature of matter increases under intense photoirradiation owing to photothermal conversion. The photothermal effect is sometimes a significant issue in optical manipulation usually requiring intense optical fields. Quantitative evaluation of local temperature under photoirradiation can, therefore, provide indispensable information for optical manipulation. In a previous work, we have applied fluorescence correlation spectroscopy (FCS) to monitor the temperature under the optical trapping condition in water, ethanol, and ethylene glycol. We pointed out that analyses of diffusion time of fluorescent dyes could provide information about temperature on the basis of temperature-dependent viscosities of the solvents. In the present work, the FCS thermometry was applied to seven solvents including primary aliphatic alcohols, to examine universal applicability of the method. To verify the experimental results, numerical simulations were performed on the basis of two-dimensional heat conduction at a stationary state. The numerical results on the temperature field satisfactorily reproduced the experimental data, proving that the FCS thermometry is applicable to ordinary solvents. In addition, we also performed numerical simulations on velocity fields in the solvent, to evaluate contribution of natural convection under typical optical trapping condition at light intensity of ∼MW cm^−  2. It was revealed that the contribution of the natural convection is not negligible for mass transfer in the solvents.

Nanoparticles of different compositions, sizes, and shapes are elaborated and trapped in a reproducible and stable manner using our optical fiber tip tweezers. Here we report trapping of spherical YAG  :  Ce^3  + particles of 300 and 60 nm diameters and of NaYF₄  :  Er^3  +, Yb^3  + nanorods of lengths from 640 nm to 1.9  μm. The properties of the tweezers are analyzed by video observations using Boltzmann statistics and power spectra analysis. Efficient trapping is found for the spherical particles and the small nanorods, whereas the large nanorods are efficiently trapped with only one fiber tip. The optical emission of a trapped nanorod completes the experimental results. Force calculations using the exact Maxwell stress tensor formalism are conducted to explain the experimental observations.

We fabricated cadmium selenide nanoparticles using a pulsed laser-ablation scheme in superfluid helium. The fabricated nanoparticles showed photoluminescence blinking and a clear blueshifted emission whose linewidth was nearly equal to the homogeneous linewidth. These results demonstrate that our method can prepare quantum dots with a sharp resonance directly in superfluid helium, enabling the further implementation of resonant optical manipulation and optical trapping in cryogenic systems.

The throughput and label-free multianalyte interrogation ability provided by surface plasmon resonance imaging (SPRi) sensors has gained considerable interest in biochemical analysis. Here, we report an optical platform based on polarization contrast modulation, in which a three-dimensional plasmonic microwell array is used as a sensing chip to eliminate background resonance and greatly enhance the electromagnetic field response in the microwell structure by confining the SPR. In addition, the sensor can provide an extremely high contrast and signal-to-noise ratio and can achieve a very high sensitivity response (1.52  ×  10⁵  pixel  /  RIU). Additionally, the signal-to-background ratio is improved to 40. The low-concentration limit of detection can reach 5.38  ×  10^−  7  RIU, which is 1 order of magnitude improvement. In biomolecular interaction analysis, the sensor can detect a 5.12  ×  10⁴-fold diluted bovine serum albumin antibody solution. The special chip architecture and high image quality introduce an array screening method using SPRi detection.

Monolithic passively mode-locked lasers are investigated based on chirped multilayer InAs/InGaAs quantum-dot (QD) structure. The forward and backward tracings of light–current characteristics show two kinks and two hysteresis loops. The optical spectra reveal two lasing wavelengths around 1273 and 1230 nm, which are identified as two ground-state emissions of two differently chirped QD layers. The corresponding radio-frequency (RF) spectra of high-speed detector reveal two RF peaks at 16.21 and 16.03 GHz, which are attributed to fundamental mode-locking of two respective wavelengths. The laser pulses are confirmed by optical autocorrelator to exhibit dual-wavelength mode-locking. The pulsed characteristics of two lasing wavelengths are also discussed in terms of operating conditions.

A compact surface plasmon photonic-crystal fiber (PCF) polarization filter is proposed and analyzed at the two communication windows of 1310 and 1490 nm, respectively. The x-polarized mode can be filtered out at the wavelength of 1310 nm, while the y-polarized mode can be excluded at λ  =  1490  nm. Therefore, the reported PCF design can be used as x-polarized or y-polarized filters using the same design. The effects of the geometrical parameters of the PCF on the performances of the polarization filter are studied by the full vectorial finite-element method. The numerical simulations reveal that the suggested polarization filter with a compact length of 150  μm can achieve good cross talk (CT) of −78 and −80.7  dB at the communication wavelengths of 1310 and 1490 nm, respectively. Further, bandwidths (BW) of 97 nm and 580 nm can be obtained around wavelengths of 1310 and 1490 nm, respectively, where the CT is better than −20  dB. Therefore, the reported design has advantages in terms of low cross talk, large BW, short device length, and multifunctionality.

The nonlinear optical properties of zinc oxide (ZnO) nanoparticles and tungsten doped zinc oxide (ZnO  :  WO₃) nanoparticles are investigated by using the Z-scan technique. The ZnO was synthesized by sol–gel method. Also, the nanoparticles of ZnO  :  WO₃ with the different molar ratio of tungsten were synthesized by sol–gel method. The result reveals that the nonlinear refractive index of ZnO is enhanced due to the addition of tungsten. Also, by adding molar ratio of tungsten doped in ZnO, the nonlinear refractive index is increased.

We report the investigation of the influence of plasmonic aluminum nanoparticles (Al-NPs), randomly dispersed into the blue organic light-emitting diode (OLED) subject to exciplex emission. The results show that, on the one hand, for the device without Al-NPs, two emission peaks at 437 and 470 nm attributed to excitons of the emitting layer (EML) and exciplexes formed at the hole transport layer/EML interface, respectively. On the other hand, for the device with Al-NPs, the exciplex emission has almost disappeared due to the localized surface plasmonic resonance effect. Moreover, the effective coupling between excitons and localized surface plamson of Al-NPs improved the radiative emission rate of the EML. We observed an enhancement of 50% of the luminous efficiency of the plasmonic-OLED device. In addition to that, the exciton lifetime of the reference sample without metallic nanoparticles is found 1.6 ns, whereas that of the plasmonic sample is prominently decreased to 0.7 ns, emphasizing the plasmonic effect of Al-NPs on the emission of our blue-OLEDs.

DNA nanoballs (DNBs) are the basis of combinatorial probe anchor ligation sequencing and the subject of multiple antisense oligonucleotides delivery research. To monitor and recognize the DNBs accurately in the procedure of genome sequencing or drug delivery is essential. Here, a super-resolution method called parametric indirect microscopic imaging (PIMI) is applied to image the DNBs. By generating the necessary polarization azimuth, phase variation, and Stokes parameters through polarization modulation, the variation of point fields in a sample can be precisely recorded and used to describe how light coupling and scattering are different from point to point. Based on the Jones paraxial propagation model and the goodness of fit to the variation curve, the image resolution is no longer limited by optical diffraction after filtering off the scattering from all uncorrelated surrounding objective field points. Results show that PIMI can reveal the spatial distribution and morphology of DNBs, break the diffraction limit, and bring the resolution within 150 nm. We proved the advantages of PIMI for its super-resolving power of DNBs in a label-free, wide-field imaging manner, which opens opportunities for developing low cost, high throughput imaging tools for DNB metrology applications.

A comparative study of sensitivity of guided-wave surface plasmon resonance (NGWSPR) biosensors with Au, Ag, Cu, and Al is presented. The thicknesses of metal films in NGWSPR biosensors were optimized first to realize minimal reflectivity at resonance angle. Then, the sensitivities of NGWSPR biosensors were optimized by optimizing the thickness of dielectric film, and the peak sensitivities for different metals are determined. By comparing peak sensitivities of different metals, we find that the Ag-based NGWSPR biosensor always exhibits largest peak sensitivity for different dielectrics, followed by Cu-, Au-, and Al-based ones. When using PbS as the dielectric in the NGWSPR biosensor, the largest peak sensitivity of Ag-based NGWSPR biosensor is up to 232.48  deg  /  RIU at 632.8 nm wavelength, which is 45.72%, 31.58%, or 271.49% higher than the sensitivity of Au-, Cu-, or Al-based ones. In addition, the reflectance curves and electric field intensity distributions of optimized NGWSPR biosensors with different metals are studied to analyze the origin of high sensitivity achieved by Ag. Furthermore, the effect of the number of graphene layers on the peak sensitivity of an NGWSPR biosensor is also investigated. It is believed that the sensitivity comparison of graphene-based NGWSPR biosensors with Au, Ag, Cu, and Al could be helpful for highly sensitive biosensors development.

A cost-efficient multimode interference-based sensor with corroded polarization-maintaining fiber (PMF) is proposed and experimentally demonstrated for the measurement of liquid refractive index (RI) and temperature. The sensor consists of a segment of corroded PMF and two segments of multimode fiber (MMF). Two segments of MMF, which are used as beam splitter and combiner are embedded on both ends of the PMF. The all-fiber sensor is put in the middle of the single-mode fiber. The RI and temperature characteristics of the sensor are investigated experimentally. The results show that two resonant peaks have different spectral responses of RI and temperature changes, which indicate that the sensor can realize simultaneous RI and temperature measurements. The experimental result shows that the high RI sensitivity is up to 318.279  nm  /  RIU in the RI range from 1.333 to 1.350 and the high temperature sensitivity is 0.188  nm  /    °  C in the range from 20°C to 40°C. This sensor exhibits the advantages of low cost and high sensitivity and may have potential application in RI and temperature measurements.

We propose a ring modulator based on few-layer graphene with large tunability and modulation efficiency. Compared with monolayer graphene, a few-layer graphene structure can enhance the tunability linearly. In the proposed structure, the shift of resonance wavelength can be enlarged to 20.3 nm, implying the proposed modulator can achieve the bandwidth of 100 GHz. In addition, a large extinction ratio of 15.5 dB and a good temperature tolerance of 45 K can be obtained in this modulator.

We propose, analyze, and simulate a configuration to realize all-optical logic gates based on nanoring insulator–metal–insulator (IMI) plasmonic waveguides. The proposed plasmonic logic gates are numerically analyzed by finite element method. The analyzed gates are NOT, OR, AND, NOR, NAND, XOR, and XNOR. The operation principle of these gates is based on the constructive and destructive interferences between the input signal(s) and the control signal. The suggested value of transmission threshold between logic 0 and logic 1 states is 0.25. The suggested value of the transmission threshold achieves all seven plasmonic logic gates in one structure. We use the same structure with the same dimensions at 1550-nm wavelength for all proposed plasmonic logic gates. Although we realize seven gates, in some cases, the transmission of the proposed plasmonic logic gates exceeds 100%, for example, in OR gate (175%), in NAND gate (112.3%), and in XNOR gate (175%). As a result, the transmission threshold value measures the performance of the proposed plasmonic logic gates. Furthermore, the proposed structure is designed with a very small area (400  nm  ×  400  nm). The proposed all-optical logic gates structure significantly contributes to the photonic integrated circuits construction and all-optical signal processing nanocircuits.

The tunable absorption effects with cascaded graphene nanoribbon arrays are investigated. It is achieved by cascading two pairs of graphene nanoribbon arrays-dielectric spacers on a metallic mirror. It is found that dual-band and a broadband absorbers can be easily achieved by tuning the geometry parameters of the structure. The designed dual-band graphene absorber exhibits near-unity absorption at two resonant frequencies and the broadband absorber shows high absorption over a wide frequencies range. Moreover, the absorption performance can not only be tuned in wide frequency ranges by changing the Fermi level, but also be maintained over a large incident angle range. It is believed that the concepts can be expanded to design multiband and more broadband absorbers by cascading many pairs of graphene nanoribbon arrays-dielectric spacers.

Using first-principle calculations, we compare the quantum efficiency and stability of Cs-GaN planar model and Cs-GaN nanowire model. The results show that the work function of GaN nanowire photocathodes decreases continuously with the increase of θ_Cs, the “Cs-kill” phenomenon disappears, resulting in a lower work function (1.76 eV) than the conventional GaN planar photocathodes (1.82 eV). However, we find that the nanowire GaN photocathodes had a lower stability by calculating the adsorption energy. In addition, the surface atomic structures of both kinds of photocathodes are almost identical, which account for the similarity of their best adsorption sites. Our study is helpful to the growth of GaN nanowire materials in the future and can be used to guide the improvements of GaN-based equipment photoelectric efficiency.

We present a numerical study of the effect of anisotropy on the spectral characteristics of one-dimensional porous silicon microcavity (1D-PSMC) with single defect layer. These structures have strong potential applications in optical sensing of chemicals and bioanalytes. Bruggeman’s effective medium approximation (BEMA) and (4  ×  4) general transfer matrix method are used for theoretical modeling of spectral response of anisotropic 1D-PSMC. The potential of this structure as a sensing material is illustrated by analyzing wavelength shift in the defect mode induced by infiltration of biochemical analytes of different refractive indices inside the pores. Observed wavelength shift is found to be linearly dependent on the refractive index of analytes. We propose two 1D-PSMC-based sensors with a microcavity wavelength around 800 and 1200 nm. An anisotropic sensor with an operating wavelength around 800 nm shows a maximum sensitivity of 190 while an isotropic sensor with the same design parameters displays a maximum sensitivity of 150. In the case of an anisotropic sensor designed around 1200 nm, the maximum sensitivity is 260; for the isotropic sensor with similar structure, maximum sensitivity of 210 is obtained. Increased sensitivity is observed in anisotropic structures as compared to the isotropic ones. Design parameters play an integral role to obtain desired sensitivity in 1D-PSMC structure for sensor applications. These sensors can be used for high precision optical sensing of chemical-analytes, bioanalytes, gases, and environmental pollutants.

By utilizing a Joule heating decomposition method, hydrogenated multilayer graphene (MLG) has been grown on the surface of a semi-insulation 4H-SiC epitaxial layer. The Raman spectra have indicated that the sublimation speed of Si atoms, which corresponds positively to the Joule heat, had great influence on the hydrogenation degree and the layer number of the MLG. Then, a graphene/4H-SiC/graphene photodetector was fabricated and studied, showing hydrogenation-dependent dark current and photocurrent, depicting the influence of hydrogenation degree and the layer number on the Schottky barrier high (varying from 0.59 to 0.99 eV). Moreover, the sheet resistance of MLG and the specific contact resistance of graphene/Cr/Au came out to be ∼3.2  kΩ  /  sq and 7.5  ×  10^−  3  Ω  ·  cm².