We demonstrate two ultra-stable laser systems at 1064 nm by independently stabilizing two 10-cm-long Fabry–Pérot cavities. The reference cavities are on a cubic spacer, which is rigidly mounted for both low sensitivity to environmental vibration and ability for transportation. By comparing against an independent ultra-stable laser at 578 nm via an optical frequency comb, the 1064 nm lasers are measured to have frequency instabilities of 6 × 10^?16 at 1 s averaging time.

A type of scalable self-imaging capable of variable magnification or minification of periodic objects is demonstrated in the focal plane of a lens illuminated by a point source. The theory and the experimental results show that the self-imaging phenomenon can also be realized in the focal plane of a lens regardless of whether the distances satisfy the lens formula or not. The particular property of this scalable self-imaging effect is that the images in the focal plane can be controlled with different scaling factors only when the distances between the point source and the periodic object satisfy a certain condition. This discovery should open a new field of diffraction imaging and new application opportunities in precision measurement.

A resonator fiber optic gyro with the light time-division input and multiplexing output (TDM-RFOG) in the clockwise (CW) and counterclockwise (CCW) directions is proposed. The light time-division input in the CW and CCW directions can effectively suppress the backscattering induced noise. The TDM-RFOG is implemented with the 2 × 2 Mach–Zehnder interferometer (MZI) optical switch. The response time of the fiber ring resonator is analyzed, and it is demonstrated by experiments that light time-division input in the CW and CCW directions can reduce the backscattering induced noise. The suppression effectiveness of backscattering induced noise in the TDM-RFOG is determined by the extinction ratio of the optical switch, so a closed loop is designed to adjust the phase shift difference between the two arms of the MZI optical switch to control the extinction ratio. The method using two arms of the MZI optical switch with twin 90° polarization-axis rotated splices is proposed to make the extinction ratio along both slow and fast axes greater than ?70 dB.

We theoretically demonstrate a compact all-dielectric metasurface fiber-tip lens composed of sub-wavelength amorphous silicon on the end face of a multimode fiber. The full 2π phase control was realized by varying the widths of resonant units. The tunable focal length is achieved by using the thermal-optic effect of amorphous silicon. The focal length increases from 309 μm to 407 μm when the temperature changes by 300 K. The temperature controlled all-fiber integrated lens is compact and with high efficiency and provides an excellent platform of a fiber-tip lab. Meanwhile, the proposed fiber lens does not have any structural changes during dynamic tuning, which improves the durability and repeatability of the devices.

A hollow-core fiber based on photonic quasicrystal arrays is theoretically proposed for high-quality light wave propagation with high polarization maintaining performance and low nonlinearity. This fiber, called hollow-core photonic quasicrystal fiber (HC-PQF), can simultaneously realize a high birefringence that reaches 1.345 × 10^?2 and a small nonlinear coefficient of 1.63 × 10^?3 W^?1·km^?1 at a communication wavelength of 1.55 μm due to the air-filled core and unique quasiperiodic fiber structure. To further demonstrate the controllability of the nonlinear coefficient and the application of sensor and polarization-maintaining fiber, the nonlinearity is investigated by filling different inert gases in the fiber core while the birefringence keeps a high order of 10^?2. In the wavelength range λ ∈ [1.53 μm, 1.57 μm], the dispersion is near zero and flattened. The HC-PQF is expected to be used for applications in optical communication, high power pulse transmission, polarization beam splitters, etc.

Measuring the microscopic temperature of graphene is challenging. We used cholesteric liquid crystal microcapsules (CLCMs) as temperature sensors to detect the local temperature of three-dimensional porous graphene through quantitative visualization. Based on a CLCM (～20 μm in size), we determined the temperature variation in a small area with an accuracy of 0.1°C. By analyzing the color changes between two CLCMs, we demonstrated the temperature changes dynamically in a region with a diameter of approximately 110 μm. Furthermore, by comparing the color evolution among the three CLCMs, we visualized the anisotropic thermal properties in the micro-zone. This convenient and low-cost temperature measurement method is expected to further improve graphene-based devices.

A DC current sensor based on an optically pumped atomic magnetometer is proposed. It has a high linearity in a wide operation range, since the magnetometer measures the absolute magnitude of the magnetic field produced by the current to be measured. The current sensor exhibits a high accuracy with a non-moment solenoid and magnetic shielding to suppress the influence from the environment. The absolute error of the measured current is below 0.08 mA when the range is from 7.5 mA to 750 mA. The relative error is 5.54 × 10^?5 at 750 mA.

We report an 8-channel wavelength-mode optical pulse interleaver on a silicon photonic chip. Wavelength- and mode-division multiplexing techniques are combined to increase the repetition rate of the pulses without adding the complexity of a single dimension. The interleaver uses a cascaded Mach–Zehnder interferometer architecture as a wavelength-division (de)multiplexer, an asymmetric directional coupler as a mode (de)multiplexer, and various lengths of silicon waveguides as delay lines. A pulse sequence with a time interval of 125 ps is implemented with the repetition rate being eight times that of the initial one. The demonstrated wavelength-mode multiplexing approach opens a new route for the generation of high-speed optical pulses.

We demonstrated a high-energy single-frequency erbium-doped yttrium aluminum garnet (Er:YAG) laser. With 1470 nm laser diodes (LDs) as pumping sources, single-frequency laser pulses with energy of 28.6 mJ, 21.6 mJ, and 15.0 mJ are obtained at pulse repetition frequency of 200 Hz, 300 Hz, and 500 Hz, respectively. As far as we know, this is the highest single-frequency pulse energy with the Er:YAG gain medium. With the ring cavity design, pulse duration is maintained at hundreds of nanoseconds. This high-energy single-frequency laser with hundreds of nanoseconds pulse duration is a prospective laser source for light detection and ranging applications.

We demonstrated a femtosecond mode-locked Er:ZrF₄-BaF₂-LaF₃-AlF₃-NaF (Er:ZBLAN) fiber laser at 2.8 μm based on the nonlinear polarization rotation technique. The laser generated an average output power of 317 mW with a repetition rate of 107 MHz and pulse duration as short as 131 fs. To the best of our knowledge, this is the shortest pulse generated directly from a mid-infrared mode-locked Er:ZBLAN fiber laser to date. Numerical simulation and experimental results confirm that reducing the gain fiber length is an effective way to shorten the mode-locked pulse duration in the Er:ZBLAN fiber laser. The work takes an important step towards sub-100-fs mid-infrared pulse generation from mode-locked Er:ZBLAN fiber lasers.

The generation of mid-infrared pulsed lasers was achieved in a Ho³⁺:YAG laser pumped gain-switched Cr²⁺:CdSe laser system with the shortest pulse duration of 4.15 ns. With a pump pulse duration of 50 ns and pump power of 2.7 W, the gain-switched Cr²⁺:CdSe laser achieved over 10 times pulse narrowing, obtaining the maximum peak power of 5.7 kW. The optical-to-optical conversion efficiency was 3.7%, which could be further improved with better crystal surface polishing quality. The laser central wavelength was measured to be 2.65 μm with a bandwidth (FWHM) of 50 nm. In addition, the parameter optimization for suppressing the pulse tail was discussed, while the long cavity and high output transmissivity contributed to obtaining the single-peak pulses.

We demonstrate a harmonically pumped femtosecond optical parametric oscillator (OPO) laser using a frequency-doubled mode-locked Yb:KGW laser at a repetition rate of 75.5 MHz as the pump laser. Based on a bismuth borate nonlinear crystal, repetition rates up to 1.13 GHz are realized, which is 15 times that of the pump laser. The signal wavelength is tunable from 700 nm to 887 nm. The maximum power of the signal is 207 mW at the central wavelength of 750 nm and the shortest pulse duration is 117 fs at 780 nm. The beam quality (M² factor) in the horizontal and vertical directions of the output beam are 1.077 and 1.141, respectively.

Image sticking in liquid crystal display (LCD) is related to the residual direct current (DC) voltage (RDCV) on the cell and the dynamic response of the liquid crystal materials. According to the capacitance change of the liquid crystal cell under the DC bias, the saturated RDCV (SRDCV) can be obtained. The response time can be obtained by testing the optical dynamic response of the liquid crystal cell, thereby evaluating the image sticking problem. Based on this, the image sticking of vertical aligned nematic (VAN) LCD (VAN-LCD) with different cell thicknesses (3.8 μm and 11.5 μm) and different concentrations of γ-Fe₂O₃ nanoparticles (0.017 wt.%, 0.034 wt.%, 0.051 wt.%, 0.068 wt.%, 0.136 wt.%, 0.204 wt.%, and 0.272 wt.%) was evaluated, and the effect of nano-doping was analyzed. It is found that the SRDCV and response time decrease firstly and then increase with the increase of the doping concentration of γ-Fe₂O₃ nanoparticles in the VAN cell. When the doping concentration is 0.034 wt.%, the γ-Fe₂O₃ nanoparticles can adsorb most of the free impurity ions in liquid crystal materials, resulting in 70% reduction in the SRDCV, 8.11% decrease in the decay time, and 15.49% reduction in the rise time. The results show that the doping of γ-Fe₂O₃ nanoparticles can effectively improve the image sticking of VAN-LCD and provide useful guidance for improving the display quality.

The effects of the diameter of SiO₂ nanopillars, the diameter of Ag nanospheres, the arrays’ period, and the medium environment on the plasmonic lattice resonance (PLR) formed by Ag nanospheres on SiO₂ nanopillar arrays are systematically investigated. Larger diameters of SiO₂ nanopillars with other parameters kept constant will widen the PLR peak, redshift the PLR wavelength, and weaken the PLR intensity. Larger diameters of Ag nanospheres with other parameters kept constant will widen the PLR peak, redshift the PLR wavelength, and strengthen the PLR intensity. Larger array periods or larger refractive index of medium environment corresponds to larger PLR wavelengths.