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Atoms interacting with a standing wave are diffracted into even multiples of photon momentum. We argue that the spreading of the atomic momentum is analogous to the fanning out of Bloch vectors of an ensemble of two-level systems in coherent optics. It is shown that a continuous, time-proportional phase increment of the standing wave reverses the dynamics of the atoms and generates momentum echoes. Monte Carlo wavefunction simulations are performed to see how the scheme works for realistic atomic models, taking spontaneous emission into account. Application of the echo formation to lifetime measurements of atoms is proposed.

The adiabaticity assumption (AA) and the resulting concept of optical potential in the context of atom focusing with lasers were examined numerically for various experimentally controllable laser parameters. The Schrödinger equations for the atomic center-of-mass dynamics in a laser field were calculated using with or without the AA, and the results were compared. The validity of the AA was tested over a wide range of the Rabi frequency to detuning ratios and the optical potential depths. From the analysis, several specific guidelines were provided on choosing laser parameters that sustain the validity of the AA and improve atom focusing outcomes.

This paper presents the implementation of a pulse-type LAser Detection And Ranging (LADAR) system based on heterodyne detection for long-range measurement. A pulse-type LADAR based on an intensity direct-detection is certainly simple and mature, but it requires a high peak-power laser and a low-noise avalanche photodiode for long-range measurement, which restricts the scope of the application due to the weight, power consumption, and cost of the laser and the photodetector. In this work, heterodyne detection using a PIN photodiode is implemented to increase receiver sensitivity instead of using a low-noise avalanche photodiode. An optical phase-locked loop is adopted to generate an optical local oscillator signal for heterodyne detection. The proposed heterodyne detection scheme achieves a minimum detectable signal level of −52.6 dBm at a bandwidth of 1.2 GHz, and it is adopted in a pulse-type LADAR system for long-range measurement. The pulse-type LADAR system can measure a distance of 2.77 km at a repetition rate of 40 kHz, and it demonstrates great advantages for realizing real-time 3D imaging for long-range measurement with a high frame rate.