Ultraslow and Stored Light Observed in Crystalline Solid
- PDF / 1,220,028 Bytes
- 2 Pages / 612 x 792 pts (letter) Page_size
- 51 Downloads / 118 Views
ditions used to induce breakdown. The LIDT for the diamond substrate was determined to be 1.20 J/cm2 and 8.0 J/cm2 for 200-ps and 100-ns pulse irradiation, respectively. The LIDT for diamond was found to be three times higher than for ZnSe, and five to six times higher than for Ge, depending on pulse length. GREG KHITROV
Ultraslow and Stored Light Observed in Crystalline Solid Ultraslow and stored light have been observed in a Pr-doped Y2SiO5 crystalline solid. A. Turukhin of JDS Uniphase and colleagues affiliated with the Massachusetts Institute of Technology, Texas A&M University, the Electronics and Telecommunications Research Institute in South Korea, and the Air Force Research Laboratory at Hanscom Air Force Base demonstrated light speeds as slow as 45 m/s
MRS BULLETIN/MARCH 2002
and even light-pulse “stopping.” Slow-light experiments work by a dramatic reduction in group velocity. To significantly slow or “stop” light, it is desirable for a material to possess a sharp feature in its dispersion relation. Such features— unusual in solid materials—can be achieved in certain insulators doped with rare-earth elements. The researchers in this study used Pr-doped Y2SiO5, which has previously been shown to exhibit electromagnetically induced transparency (EIT), and which has also been a crucial feature in atomic gases previously used for demonstrating ultraslow light. As reported in the January 14 issue of Physical Review Letters, the crystal was optically pumped by coupling and probe laser fields and produced a “spectral hole,” a region where the crystal is transparent to the laser field. Simultaneously, an auxiliary field was required to produce
an absorbing “antihole.” This auxiliary field not only controlled the probe field absorption, but also reduced the effective inhomogeneous linewidth the coupling field must overcome to achieve EIT. The group light velocity was measured by chopping the probe and determining the phase delay of the chopped signal. Individual probe pulse slowing could also be measured. An advantage of this EIT-based technique was that the group delays depended mostly on the intensity of the coupling laser. This meant that the group light speed could be altered by changing the coupling laser intensity and that complex probe pulse shapes could be effectively slowed with bandwidth serving as the only real limitation. Finally, the researchers demonstrated “stopped light.” This phenomenon occurs when the group velocity is decreased to zero while also reducing the coupling laser intensity to
169
RESEARCH/RESEARCHERS
zero. In this way, the information in the probe pulse is “mapped” into the atomic coherence of the material, and can be read out subsequently by turning the coupling laser on again. The ability to store and recover the coherent light wave depends upon the spin coherence of the system as well as decoherence effects. Since the initial “ultraslow” light observations in “cold” and “hot” atomic gases and subsequent extensions to “trapping” light, there has been considerable speculation
Data Loading...
