Li Yi-min

Experimental study of a model digital space optical communication system with new quantum devices

We report a digital space optical communication system with new features both in the transmitting and in the receiving ends. The diode laser source is stabilized to within ±100 kHz by locking its frequency to the transmission peak of a Faraday anomalous dispersion optical filter (FADOF). The optical filter in the receiver uses two FADOFs that are linked to eliminate the multipeak structure and achieve a single-peak bandwidth of ~1 GHz. The detection sensitivity of this system is 23 times higher than that of a system with a traditional interference filter.

Excited state Faraday anomalous dispersion spectrum of rubidium

Abstract This paper reports on the excited state Faraday anomalous dispersion spectrum (FADS) of rubidium based on transition 5 P 3 2 → 5 D 5 2 . Theoretical analysis and experimental studies have been made. The results showed that the peak transmission occurred at the central frequency of the transition, there was an optimal magnetic intensity at a certain temperature and pump power, and peak transmission increased with the enhancement of pump power. 16% transmission was predicted when the density of 5 P 3 2 atoms was sufficient.

A Comparative Study on the Self Diffusion of N-Octadecane with Crystal and Amorphous Structure by Molecular Dynamics Simulation

The straight chain n-alkanes and their mixture, which can be used as phase change materials (PCM) for thermal energy storage, have attracted much attention in recent years. We employ the molecular dynamics (MD) simulation to investigate their thermophysical properties, including self diffusion and melting of n-octadecane with crystal and amorphous structures. Our results show that, although the initial and melted structures of n-octadecane with crystal and amorphous are different, the melting behaviors of n-octadecane judged by the self diffusion behavior are consistent. The MD simulation indicates that both the crystal and amorphous structures are effective for the property investigation of n-octadecane and the simulated conclusion can be used as reference for modeling the alkanes-based PCM system.

Analysis of amplitude for the anti-radiation weapon antagonizing active decoy

The active decoy environment of anti-radiation weapon face is introduced, and the position between the radar and the decoy is analyzed. The new way of distinguish multiple source signal by turning PRSpsila antenna is given. Then the feasibility and the limitation are analyzed based on the discussing and testing.

A STUDY OF THE PHYSICAL PROPERTIES OF ZEEMAN ABSORPTION FARADAY ANOMALOUS DISPERSION OPTICAL FILTER

This paper reports what is to our knowledge the first demonstration of Zeeman absorption Faraday anomalous dispersion optical filter (hereafter abbreviated to FADOF/Zeeman). The mutual relations among passband, tuning capability, cell temperature and magnetic field of FADOF/Zeeman have been studied theoretically and experimentally. The results showed that the single passband of FADOF/Zeeman was about 1 GHz, which is 3 times less than the passband of FADOF. The tuning capability was about 1 GHz/0.01 T.

Magneto-Optical Trap for Cesium Atoms Without a Separate Repumping Laser

A magneto-optical trap (MOT) for cesium atoms that operates without a separate repumping laser is reported. The differences between a normal MOT and this kind of MOT have been experimentally studied. The influences of a repumping laser on cooling and trapping cesium atoms in the MOT have been carefully investigated. The results reveal that it is the critical injection-locked state of the diode laser that makes magneto-optical trapping of cesium atoms possible without a separate repumping laser.

An Improved Magneto-Optical Trap for Cesium Atom

Based on the realization of magneto-optical trap for cesium atom in China, great improvement is achieved on its performance. In the new experimental setup, a laser battery in stepwise injection-locking scheme is developed as laser source, which has more output power and better beam quality than the previous one. Under the optimum working condition, cesium atoms of more than 109 with the density of 1011 atoms/cm3 are trapped to form an atomic cloud with the diameter of 3 mm. Compared with previous results, both the number of trapped atoms and the density of atomic cloud are increased in two orders of magnitude.

Experimental study on laser cooling of cesium atoms by optical molasses

We have studied the relationship between the temperature of Cs cold atoms and the parameters of the cooling laser. The atoms are first cooled and captured by a magneto-optical trap and then further cooled by optical molasses. The temperature of atoms is measured by a time-of-flight method. For relatively large laser intensity and small detuning, the temperature depends linearly on the intensity-to-detuning ratio, and nonlinear relationship has also been found in other case.

LASER COOLING IN PHASE FLUCTUATING LASER FIELD

The influence of laser linewidth Γ1 on laser cooling of atoms was investigated theoretically by using a diffusing phase model. The final temperature which can be achieved by Doppler cooling or sub-Doppler cooling in phase fluctuating laser field is presented. It was found that the natural linewidth Γn of the transition used for cooling the atoms is an important quantity in evaluating the influence of Γ1 under Doppler cooling mechanism, and the laser linewidth has little effect on the final temperature under sub-Doppler cooling mechanism because the laser detuning is very large in this case.

Magneto-Optical Trap of Cesium Atoms

We have trapped a cold sample of cesium atoms in a magneto-optical trap. The damped harmonic force of magneto-optical trap was used to capture and trap the cesium atoms directly from a room temperature vapor. About 1.5 × 107 cesium atoms with a density of 3 × 109 atoms/cm3 formed a 4 mm3 cesium atomic cloud with temperature below 500 μK.