Locking Multi-Laser Frequencies to a Precision Wavelength Meter: Application to Cold Atoms

We herein report a simultaneous frequency stabilization of two 780-nm external cavity diode lasers using a precision wavelength meter (WLM). The laser lock performance is characterized by the Allan deviation measurement in which we find σy=10−12 at an averaging time of 1000 s. We also obtain spectral profiles through a heterodyne spectroscopy, identifying the contribution of white and flicker noises to the laser linewidth. The frequency drift of the WLM is measured to be about 2.0(4) MHz over 36 h. Utilizing the two lasers as a cooling and repumping field, we demonstrate a magneto-optical trap of 87Rb atoms near a high-finesse optical cavity. Our laser stabilization technique operates at broad wavelength range without a radio frequency element.

A Versatile Quantum Simulator for Coupled Oscillators Using a 1D Chain of Atoms Trapped near an Optical Nanofiber

The transversely confined propagating light modes of a nanophotonic optical waveguide or nanofiber can effectively mediate infinite-range forces. We show that for a linear chain of particles trapped within the waveguide’s evanescent field, transverse illumination with a suitable set of laser frequencies should allow the implementation of a coupled-oscillator quantum simulator with time-dependent and widely controllable all-to-all interactions. Using the example of the energy spectrum of oscillators with simulated Coulomb interactions, we show that different effective coupling geometries can be emulated with high precision by proper choice of laser illumination conditions. Similarly, basic quantum gates can be selectively implemented between arbitrarily chosen pairs of oscillators in the energy as well as in the coherent-state basis. Key properties of the system dynamics and states can be monitored continuously by analysis of the out-coupled fiber fields.

Study of Overlapping Adjacent Jets for Effective Laser-Induced Forward Transfer Printing

Laser-induced forward transfer (LIFT) is a well-established, versatile additive manufacturing technology for orifice-free printing of highly viscous solutions and suspensions. In order to improve the efficiency of point-wise LIFT printing, an optical scanner is integrated into the laser printing system to enable the formation of overlapping adjacent jets used for deposition. The objective of this study is to evaluate the ejection behavior and deposition performance under such conditions during LIFT printing for further improvement. The effects of the overlap of adjacent jets are investigated in terms of jet formation and material deposition processes, capturing the jet tilting phenomenon caused by the perturbance induced by previously formed jet(s). The feasibility of optical scanner-assisted LIFT printing of viscous metal-based ink suspension has been successfully demonstrated during conductive line printing with induced overlapping jets. Investigation of various overlap ratios of adjacent jets found that a 30% jet overlap and a 133 µs time interval between laser pulses are optimal, in terms of deposition quality and ejection stability, even when a tilted jet ejection is present for the laser and material system in this study. Furthermore, multilayer polygonal and interdigitated structures are successfully deposited under these identified printing conditions. With the inclusion of an optical scanner, LIFT printing efficiency for viscous inks can be improved as the usage of higher laser frequencies is enabled, providing a faster orifice-free laser printing methodology.

DESIGN AND IMPLEMENT OF A CONICAL AIRBORNE LIDAR SCANNING SYSTEM

At present, the main LiDAR is single-point lidar. APD arrays and laser arrays are restricted to exit, so the number of area array LiDAR is scarce. Single-point lidar can't form a scanning pattern with only one laser point on the ground after launching laser, so it must have a set of scanning device for single-point lidar. The scanning device designed in this paper forms a circular scanning area on the ground by rotating the refraction prism, and at the same time forms a conical field of view. At present, marine LiDAR uses this kind of scanner more frequently. The advantages of this scanner are: simple mechanical structure and smooth operation. Overlapping elliptical scanning trajectories can be obtained during flight, which increases scanning density. Ultra-low dispersion glass is used as refractive prism in this paper. In a certain range of laser frequencies, the refractive prism has almost the same effect on laser refraction at different frequencies. The simulation results show that the scanner can be used as a common LiDAR scanner or a dual-frequency LiDAR scanner.

Absolute laser frequency stabilization for LISA

The LISA space mission requires laser frequency pre-stabilization of the 1064[Formula: see text]nm laser sources. While cavity-based systems are the current baseline, laser frequencies stabilized to a hyperfine transition in molecular iodine near 532[Formula: see text]nm are a possible alternative. Several setups with respect to space applications were developed, putting special emphasis on compactness and mechanical and thermal stability of the optical setup. Vibration testing and thermal cycling were performed. These setups show frequency noise below 20[Formula: see text]Hz/[Formula: see text] for frequencies between 4[Formula: see text]mHz and 1[Formula: see text]Hz with an absolute frequency reproducibility better than 1[Formula: see text]kHz. They fulfil the LISA requirements and offer an absolute laser frequency simplifying the initial spacecraft acquisition procedure. We present the current status of iodine-based frequency references and their applicability in space missions, especially within the LISA mission.

On the Recovery of PLP-Molar Mass Distribution at High Laser Frequencies: A Simulation Study

Due to the inherent difficulties in determination of the degree of branching for polymers produced in pulsed laser polymerization (PLP) experiments, the behavior of the degree of branching and backbiting reaction in high laser frequency and relatively high reaction temperatures have not been well-established. Herein, through a simulation study, the validity of different explanations on the recovery of PLP-molar mass distribution at high laser frequencies is discussed. It is shown that the reduction of the backbiting reaction rate at high laser frequency, and consequent decrease in the degree of branching, is not a necessary condition for recovering the PLP-molar mass distribution. The findings of this work provide simulation support to a previous explanation about the possibility of using high laser frequency for reliable determination of the propagation rate coefficient for acrylic monomers.

Access to the β-scission rate coefficient in acrylate radical polymerization by careful scanning of pulse laser frequencies at elevated temperature

A novel method to estimate the β-scission rate coefficient in acrylate radical polymerization is presented.