ABSTRACT
We present a laser-driven interferometric fiber optic gyroscope (IFOG) with polarization self-compensation to achieve high scale-factor stability, sensitivity, and long-term stability. Coherent light with 200kHz linewidth is employed to keep the scale factor stable. The optical scheme ensures polarization reciprocity as well as the optimal working point for good sensitivity. Furthermore, a hybrid machine learning loop (MLL) method, combining the advantages of PID fast response and artificial neural network (ANN) dynamic search, can control a liquid crystal rotator (LCR) to dynamically compensate for slow drift induced by polarization coupling. In open environment, when the sensitivity is 0.005 ∘/h, the bias instability (BI) is significantly optimized from 0.6723°/h at 60s (PID) to 0.3869°/h at 200s (MLL), which is close to the Sagnac interferometric limit (SIL). Such IFOG can meet the real-time and robust requirements for inertial navigation systems in long-term measurement.
ABSTRACT
We demonstrate an integrated laser system for the mobile integrating sphere cold atom clock. Three distributed Bragg reflector diode lasers (780 nm) with custom drive circuits are used for the cooling, repumping, pumping, and probe lights. Automatic frequency-locking and relocking of the laser are presented. All of the optical elements are integrated on two sides of an aluminum base plate. The mechanical structure is simulated and optimized to minimize the deformation of the base plate. We optimize, measure, and discuss the frequency and intensity noises of the laser system. The techniques and designs used in this laser system can also be used in other mobile platforms for quantum sensing experiments.
ABSTRACT
The nonlinear spectroscopy of cold atoms in the diffuse laser cooling system is studied in this paper. We present the theoretical models of the recoil-induced resonances (RIR) and the electromagnetically-induced absorption (EIA) of cold atoms in diffuse laser light, and show their signals in an experiment of cooling (87)Rb atomic vapor in an integrating sphere. The theoretical results are in good agreement with the experimental ones when the light intensity distribution in the integrating sphere is considered. The differences between nonlinear spectra of cold atoms in the diffuse laser light and in the optical molasses are also discussed.
Subject(s)
Algorithms , Lasers , Models, Theoretical , Radioisotopes/analysis , Rubidium/analysis , Spectrum Analysis/methods , Cold Temperature , Computer Simulation , Nonlinear DynamicsABSTRACT
Four new Daphniphyllum alkaloids, daphnilongeranins A-D (1-4), along with four known ones, daphniphylline, longistylumphylline A, deoxyisocalyciphylline B, and daphnicyclidin D, were isolated from the leaves and stems of Daphniphyllum longeracemosum. Daphnilongeranin A (1) is the first seco-10,17-longistylumphylline A type Daphniphyllum alkaloid, and daphnilongeranin B (2) is a new C-22 nor-Daphniphyllum alkaloid based on a new C21 skeleton. Their structures and stereochemistry were determined using spectroscopic data and chemical methods.
Subject(s)
Alkaloids/chemistry , Alkaloids/isolation & purification , Drugs, Chinese Herbal/chemistry , Drugs, Chinese Herbal/isolation & purification , Plants, Medicinal/chemistry , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Plant Leaves/chemistry , Plant Stems/chemistryABSTRACT
The momentum transfer dependence of fundamental double excitation processes of helium is studied by absolute measurements using an angular resolved fast-electron energy loss spectrometer with high energy resolution. It elucidates the dynamical correlations, in terms of internal correlation quantum numbers, K, T, and A. The Fano profile parameters q, f(a), rho2, f, and S of doubly excited states (2)(1,0)+2 (1)S(e), (2)(1,0)+2 (1)D(e), and (2)(0,1)+2 (1)P(o) are reported as functions of momentum transfer K2. Qualitative analysis is given for the states of (2)(-1,0)+2 (1)S(e) and (2)(1,0)+2 (1)S(e).