Persistent Hole Burning and Femtosecond Photon Echo Using Diode Laser

1.首次利用连续波多模半导体激光器和超辐射发光二极管实现了非相干光光子回波.持续烧孔技术因其作为未来多波长光存储器的潜力而备受关注。在传统半导体激光器的波长范围（780 nm附近），我们发现了一种高效的持续烧孔材料HITC/PVA.利用改变注入电流的波长扫描技术，我们观测到了HITC/PVA中持续空穴的时间演化，时间分辨率为10毫秒.我们发现HITC/PVA的持续孔洞在一次燃烧后可以被证明1000次以上.利用上述方法，我们观察到了HITC/PVA中持续空穴的光谱扩散和自填充过程.我们观察了HITC/PVA（聚合物基质）和HITC/EtOH（单体基质）两个样品中持续空穴的时间演化，并通过假设基质中的二能级系统在空间上呈分形分布来解释这种行为。该理论给出了光子回波衰减曲线、持续空洞形状和空洞宽度随温度的变化关系，这些都与分形维数D有关。通过与实验的比较，我们得到D=2.1 - 2.3的HITC/PVA和D=2.7的HITC/乙醇。

1. The incoherent light photon echoes by using a cw multi-mode diode laser or a superluminescent diode have been performed for the first time.2. Persistent hole burning has been attracting much attention because of its potentiality as future multi-wavelength optical memory. We found out an efficient persistent hole burning material HITC/PVA at the wavelength region of conventional diode lasers, near 780 nm.3. Using the wavelength sweep by changing the injection current into diode lasers, we observed the time evolution of the persistent hole in HITC/PVA with a temporal resolution of 10 msec.4. We found that the persistent hole in HITC/PVA can be proved more than 1000 times when it was once burnt.5. By using the methods mentioned above, we observed spectral diffusion and self-refilling process of the persistent hole in HITC/PVA.6. We observed the temporal evolution of persistent holes in two samples HITC/PVA (polymeric host) and HITC/EtOH (monomeric host), and explained the behavior by assuming that the two level systems in the host are spatially distributed like a fractal. This theory gives the photon echo decay curve, persistent hole shape and the temperature dependence of the hole width which depend on the fractal dimension D. By comparison with the experiment, we obtained D=2.1 2.3 for HITC/PVA and D=2.7 for HITC/EtOH.