We report a novel nonresonant magneto-optical effect in cold atoms and present the optimized parameters of the biased magnetic field, the incident probe light intensity, and the probe detuning to obtain the maximal signal of the magneto-optical rotation. This detection scheme may further improve the stability of the cold atom clock.

We propose an LED reshaping lens design for a handheld underwater wireless optical system to solve the problem of targeting the receiver. The simulation results shows that the designed lens can achieve 0.91 light intensity uniformity and 91.39% optical efficiency in hemisphere space, even with the actual LED model. After fabrication with computer numeric control, the work demonstrates the design to be effective.

The electric field distribution in LiNbO3 crystal under different electrode shape is presented by using the digital holographic interferometry. Three configurations of phase modulator including the rectangular electrode type, single-triangle electrode type, and dual-triangle electrode type are performed in this experiment. The nonuniform electric field distribution in these phase modulators are observed and the electric field increases with voltage increasing. The digital holographic interferometry with high electro-optic effect improves the measurement precision. The digital holographic interferometry provides an effective way for studying the electric field distribution. Such in situ quantitative analysis of electric field distribution is a key to optimizing electrode shape.

We report, for the first time to our knowledge, a diode-end-pumped passively mode-locked (ML) Nd-doped gadolinium gallium garnet laser based on a chemically reduced graphene oxide (RGO) saturable absorber mirror. The ML laser gives a pulse duration of 15.1 ps under the maximum average output power of 1.44 W, corresponding to a slope efficiency of 21.1%. The single-pulse energy and peak power are 21.6 nJ and 1.43 kW, respectively. The results indicate that our RGO saturable absorber has promising prospects for applications in high-power and high-efficiency ultrafast lasers.

A depolarization phenomenon in an electro-optical crystal in a quasi-three-level 946 nm Nd:YAG laser is observed. A compensation of the thermal effects in electro-optical crystals is achieved by employing a quarter-wave plate, with one optical axis parallel to the laser polarization. This technique allows for the production of an electro-optically Q-switched 946 nm Nd:YAG laser at 1 kHz. A maximum output power of 350 mW at 1 kHz repetition frequency and 11 ns pulse duration are achieved with an output coupler of 10% transmission under the incident pump power of 11.1 W, corresponding to a peak power of ～32 kW.

We demonstrate a high-pulse-energy, short-pulse-width passively Q-switched (PQS) Nd:YAG/V3+:YAG laser at 1.3 μm, which is end-pumped by a pulsed laser diode. During the PQS regime, a maximum total output pulse energy of 3.3 mJ is obtained under an absorbed pump pulse energy of 21.9 mJ. Up to 400 μJ single-pulse energy is realized with the shortest pulse width of 6.16 ns and a pulse repetition frequency of 34.1 kHz, corresponding to a peak power of 64.9 kW. The high-energy laser pulse is operated in the dual wavelengths of 1319 and 1338 nm, which is a potential laser source for THz generation.

Owing to the small differences between the cross-sections of the four emission peaks around 1.3 μm, an efficient four-wavelength synchronous launched laser is demonstrated using a Nd:GdLuAG crystal. The laser has no special resonator design. The maximum output power is 4.28 W, which corresponds to a conversion efficiency of 45.6%. For the Q-switching, the laser operated in dual-wavelength mode, and the single pulse energy is maintained at ～80 μJ. By calculating the population inversion density, multi-wavelength emission characteristics in both continuous wave and Q-switching lasers are discussed.

We report an adjustable unbalanced quantum random-number generator based on the polarization of photons, which can produce nondeterministic true random unbalanced numbers. The underlying physical process is inherently quantum mechanical. To prove the quality of the output sequence of the proposed generator, we test the obtained bias-free sequence through the 3-standard-deviation criteria and the National Institutes of Standards and Technology test suite. Another type of nondeterministic unbalanced random-number generator is also studied in this work, to evaluate the quality of the output biased random numbers.

Surface plasmonic polariton (SPP) waves with complicated wavefronts have important implications in nanophotonic sciences and applications. The surface electromagnetic wave holography method is applied to designed grooves on a metal surface for coupling a plane wave in free space to complicated wavefront SPP waves. The grooves illuminated by the plane wave incident from free space serve as secondary SPP waves sources, that radiate cylindrical SPP waves. New controllable wavefronts originate from these secondary SPP waves interfering with each other, based on the Huygens–Fresnel principle. Several applications of the method are demonstrated, such as converting coupling waves in free space into focusing SPP waves on a metal surface.

A hexagonal array grating based on selective etching of a 2D ferroelectric domain inversion in a periodically poled MgO-doped LiNbO3 crystal is fabricated. The effects to the diffractive self-imaging as a function of diffraction distance for a fixed phase difference and array duty cycle of the grating is theoretically analyzed. The Talbot diffractive self-imaging properties after selective etching of a 2D ferroelectric domain inversion grating under a fixed phase difference are experimentally demonstrated. A good agreement between theoretical and experimental results is observed.

Wide dynamic range is an important index of the resonator fiber optic gyro (RFOG). The dynamic range is related to the parameters of the fiber ring resonator (FRR). After adopting the appropriate parameters, the resonant curve of a FRR and the synchronous demodulated curve are measured. Based on the closed-loop frequency locking technique, the wide dynamic range is obtained, while the linearity is guaranteed. The experiment’s results show that the dynamic range is ±480 deg/s with less than 1% nonlinearity, and that the bias stability is 0.04 deg/s over 2000 s. This Letter demonstrates the scheme for a RFOG with a wide dynamic range.

The spin effect on a single-mode single-polarization optical fiber is investigated theoretically and numerically. To get a practical single elliptically polarized fiber the normalized spin rate must be in the range of 0.2–0.35. A single elliptically polarized fiber with a normalized spin rate around 0.224 is demonstrated. It has a broad band from 1.530 to 1.558 μm, in which the low-leakage elliptically polarized eigenmode loss is kept within 1.2 dB while the high-leakage elliptically polarized eigenmode loss is greater than 20 dB. This fiber can be used as an elliptical polarizer or applied in current sensing.

We experimentally demonstrate a channel-reuse bidirectional 10 Gb/s/λ long-reach dense wavelength-division multiplexing passive optical network (DWDM-PON) and an optical beat-noise-based automatic wavelength control method for a tunable laser used in a colorless optical network unit (where λ=wavelength). A 55 km, bidirectional, 400 Gb/s (40×10 Gb/s) capacity channel-reuse transmission with 100 GHz channel spacing is achieved. The transmission performance is also measured with different optical signal to Rayleigh backscattering noise ratios and different central wavelength shifts between upstream and downstream in the channel-reuse system.

An angular trapezoidal phase mask used for a wideband coronagraph is proposed. The azimuthal phase of the mask is double-periodic and has both trapezoidal and constant parts in each period. This kind of continuous phase distribution can be employed to avoid the abrupt phase variation of the 6-level phase distribution we proposed previously. Numerical calculations show that this more practical phase mask can still keep its superior performance in terms of starlight elimination, small inner working angle, and good achromatism. It is of great importance that there is no singularity in this kind of mask except for a singularity at the center. This mask design is close to real manufacturing conditions, and the process technology is superior.

The films of few-layer graphene are formed through laser exfoliation of a highly ordered pyrolytic graphite (HOPG), without a catalytic layer for the growth process. The femtosecond (fs) laser exfoliation process is investigated at different laser fluences and substrate temperature. For fs laser exfoliation of HOPG, the few-layer graphene is obtained at 473 K under an optimal laser fluence. The formation of few-layer graphene is explained by removal of intact graphite sheets occurred by an optimal laser fluence ablation. The new insights may facilitate the controllable synthesis of large area few-layer graphene.

Infrared-to-visible upconverted luminescent spectra of Er3+ and La3+ codoped Y2O3 powders are investigated. By introducing La3+ ions, the upconversion green radiation is found to be greatly enhanced when compared with the powders with La3+ absent. Such enhancement can be attributed to the modification of the local symmetry surrounding the Er3+ ion, which benefits the intra-4f transitions of Er3+ ion, and the decreasing interaction between Er3+ ions, which suppresses the energy transfer process F7/24+I411/2→F49/2+F49/2</mml

We prepare SiO2 coatings on different substrates by either electron-beam evaporation or dual ion-beam sputtering. The relative transmittances of the SiO2 coatings are measured during the heating process. The SiO2 coating microstructures are studied. Results indicate that the intensity and peak position of moisture absorption are closely related to the microstructures of the coatings. The formation of microstructures depends not only on the preparation process of the coatings but also on the substrate characteristics.

We design a plano-convex lens working in the terahertz (THz) frequency range and fabricate it using three-dimensional (3D) printing technology. A 3D field scanner is used to measure its focal properties, and the results agree well with the numerical simulations. The refractive index and absorption coefficient measurements via THz time-domain spectroscopy (THz-TDS) reveal that the lens material is highly transparent at THz frequencies. It is expected that this inexpensive and rapid 3D printing technology holds promise for making various THz optical elements.

In this Letter, we study the characteristics of a selectively buried glass waveguide that is fabricated by the backside masking method. The results show that the surface region appears when the width of the backside mask is larger than 7 mm. Here, the glass substrate is 1.5 mm thick. It is also found that the buried depth evolution of the transition region remains almost unchanged and is independent of the width of the backside mask. The loss of the transition region is only 0.28 dB at the wavelength of 1.55 μm if the surface condition is good enough.