We investigate the resonance fluorescence spectrum of an atomic three-level ladder system driven by two laser fields. We show that such a system emulates to a large degree a V-type atom with parallel dipole moments-the latter being a system that exhibits spontaneously generated coherence and can display ultrasharp spectral lines. We find a suitable energy scheme in a SSRb atom and experimentally observe the narrowing of the central peak in a rubidium atomic beam. The corresponding spectrum can convindngiy demonstrate the existence of spontaneously generated coherence.
We experimentally study the generation and storage of double slow light pulses in a pr^3＋：Y2SiO5 crystal. Under electromagnetically induced transparency, a single signal pulse is stored in the spin coherence of the crystal. By simultaneously switching on two control fields to recall the stored information, the spin coherence is converted into two slow light pulses with distinct frequencies. Furthermore, the storage and controlled retrieval of double slow light pulses are obtained by manipulating the control fields. This study of double slow light pulses may have practical applications in information processing and all-optical networks.
Fan Yun-FeiWang Hai-HuaWang RongZhang Xiao-JunKang Zhi-HuiWu Jin-HuiZhang Han-ZhuangGao Jin-Yue
We study the theoretical and experimental effects of hole quantity and inter inter-hole spacing on insertion loss for using femtosecond laser to make bend-sensitive multi-hole plastic optical fiber （POF）, and also analyze the mechanism of bending loss in multi-hole POF. A force sensor based on bending loss of the multi-hole POF is fabricated. The measurement ranges from 0 to 65 N, and the maximum output change exceeds 15.51 dB with good linearity and repeatability, and the sensitivity is 0.24 dB/N.
A compact in-fiber refractive index （RI） sensor based on a step index multimode polymer optical fiber with a micro-hole drilled by a miniature numerical control machine is presented. A good linear relationship between the transmission and RI over a large operating range from 1.335 to 1.475 and a sensitivity of 36 071.43 mV/RIU （RI unit） are found. The relationship between the transmission and the RI of the hole depends on the micro-hole＇s diameter and depth. The RI sensor developed in this letter is low-cost, easily fabricated, and capable of continuous measurement.
