Dual-wavelength synchronous control method for liquid crystal optical phased array.

The liquid crystal optical phased array (LCOPA), as a key beam steering device, has gained increasing significance in the field of space laser communication. With the rapid advancement of space laser communication technology, the demand for precise synchronous control of multi-wavelength beams has significantly increased, particularly in ensuring reliable communication links through synchronized control of signal and beacon beams. The signal beam is primarily utilized for data transmission, while the beacon beam is responsible for path calibration and real-time tracking.

Panoramic laser communication optical systems for low Earth orbit satellite networking.

Laser communication, which is known for its high data rate and large capacity, is a promising solution for future large-scale satellite constellation networking. However, the limited field of view (FOV) of current communication terminals makes establishing inter-satellite links challenging. This paper presents a wide-field optical system for laser communication that addresses the challenge of the limited field of view (FOV) in current satellite terminals.

Configuration optimization and optical transmission simulation of a conformal fairing under a hypersonic thermal environment.

When an aerospace vehicle flies within the atmosphere, aerodynamic heating can affect the surface shape and the refractive index of the optical fairing, leading to imaging distortion and deviation in the subsequent optical system. To address this issue, this paper proposes a novel, to the best of our knowledge, concept for a conformal optical fairing design. This compares the imaging performance, stagnation point temperature, and drag coefficient of four traditional fairings.

A novel pansharpening method based on side window filter and new injection gain matrices.

The acquisition of remote sensing images with both high spatial resolution and high spectral resolution is constrained by limitations in spectral imaging technology. Pan-sharpening is utilized to generate high-resolution multispectral images that correspond to the resolution of panchromatic (PAN) images through the fusion of multispectral (MS) and PAN images. Traditional methods frequently encounter challenges associated with the loss of image details.

Wavefront-coded image restoration technology based on multi-scale deep neural networks.

Optical imaging systems are significantly affected by aerodynamic thermal effects under varying flight conditions, resulting in complex image blurring. To address this challenge, this study proposes a novel wavefront-coded image restoration method based on a multi-scale deep autoencoder neural network (MS-DAE). By modulating blur levels and incorporating a multi-scale loss function with residual attention mechanisms, the proposed method achieves a remarkable improvement in peak signal-to-noise ratio (PSNR) by 16.

Dynamic simulation imaging for complex atmospheric turbulence scenes based on atmospheric coherence length and associated with phase structure function.

Atmospheric turbulence disturbance degrades the quality of long-range image transmission in applications such as marine monitoring and satellite imaging. Simulating an atmospheric turbulence image dataset facilitates the correction of turbulence-distorted images. However, the current simulation algorithms suffer from long computation times, undersampling of frequency, and unrealistic turbulence image simulation.

A Method for Mounting Space Telescope Optical Systems Based on the Sensitivity Matrix of Intrinsic Coefficients.

Aperture space telescopes are widely used in space debris size information detection and celestial body detection work. For the problem of limited space inside the optical system of large aperture telescopes, a space telescope mounting method based on the intrinsic coefficient sensitivity matrix is proposed by combining the wavefront detection technology. Compared with the traditional sensitivity matrix method, the method in this paper does not need to partition the detector and simplifies the construction of the wavefront reconstruction matrix.

2.05 μm high-energy thulium-doped fibre amplifier based on backward pumping.

We demonstrate a thulium (Tm)-doped fibre amplifier using a Ho: GdVO solid-state laser as the master oscillator operating at 2048.53 nm. In experiment, a novel spatial coupling system was used, combining a single lens with a curved end cap to simplify the structure and reduce losses.

Dual-wavelength transmission based on liquid crystal tunable filter with high signal-to-noise ratio.

Aiming at the problem of limited transmission energy of liquid crystal tunable filter (LCTF), a dual-wavelength transmission system with high signal-to-noise ratio (SNR) is proposed in this paper. The proposed transmission factor Qp is the main influence on the number and location of transmission wavelengths as well as the bandwidth of each transmission wavelength for dual-wavelength systems. Dual-wavelength LCTF can improve the effective transmission energy of the system by increasing the number of filtering channels, and the transmission energy can be increased by about 1.

Research on one-to-two-point FSO system based on liquid crystal variable retarder cascade polarization grating.

We experimentally demonstrated a one-to-two-point free-space optical communication (FSO) system based on non-mechanical beam servo device in the laboratory. After the initial pointing, two sets of liquid crystal variable retarder cascaded polarization gratings perform non-mechanical beam servo and realized switching or working simultaneously of two communication links. The non-mechanical beam steerer had four diffraction fields; each can achieve beam steering with a 3.

Design of achromatic annular folded lens with multilayer diffractive optics for the visible and near-IR wavebands.

In this paper, the annular folded lens (AFL) is applied to the realization of a miniaturized system for the visible and near-IR spectrums (0.45-1.1μm).

Tunable multiwavelength Tm-doped fiber laser based on the multimode interference effect.

A simple multiwavelength Tm-doped fiber laser at the 2 μm band based on multimode interference (MMI) is proposed and experimentally demonstrated. In this scheme, a 4 m Tm-doped single-mode fiber is pumped by a 1568 nm laser, and a single-mode-multimode-single-mode (SMS) fiber structure is used as an MMI filter in which the multimode fiber is used to tune the laser. Laser operation of up to three wavelengths is obtained based on the MMI filter.

Frequency switched narrow linewidth microwave signal photonic generation based on a double-Brillouin-frequency spaced fiber laser.

A simple photonic approach to generate microwave frequency switched microwave signal is proposed and experimentally demonstrated. In this scheme, a Brillouin fiber laser with double-Brillouin-frequency spacing is used. The Brillouin ring configuration suppresses incoming Brillouin pump and even-order Stokes signals in the cavity.

Stereoselective construction of fluorinated indanone derivatives via a triple cascade Lewis acid-catalyzed reaction.

A one-pot three-component cascade reaction proceeds by way of a Lewis acid-catalyzed Knoevenagel condensation/Nazarov cyclization/electrophilic fluorination sequence to afford fluorinated 1-indanone derivatives in moderate to good yields with high diastereoselectivities.

Highly enantioselective Michael addition of aromatic ketones to nitroolefins promoted by chiral bifunctional primary amine-thiourea catalysts based on saccharides.

[reaction: see text] A new class of thiourea catalysts have been developed which integrate saccharide and primary amine moieties into one small organic molecule. These simple catalysts are shown to be highly enantioselective for direct Michael addition of aromatic ketones to a range of nitroolefins (up to 98% ee).