Slow light with persistent hole burning

Abstract

We consider the propagation of a Gaussian probe pulse in an absorptive, optically dense, two-level medium if a deep, persistent hole is created in advance by another pump field in the inhomogeneously broadened absorption spectrum of this medium. Both fields are well separated in time and the lifetime of the hole is assumed to be long with respect to the delay time between the pump and probe pulses. We show that the group velocity of the Gaussian probe pulse reduces several orders in magnitude, similarly to the reduction of the group velocity for the probe field in electromagnetically induced transparency ͑EIT͒ phenomena. In contrast to EIT, the width of the transparency window can be made very wide because of the saturation broadening of the hole.

Spectral Engineering of Slow Light, Cavity Line Narrowing, and Pulse Compression

“…1 shows that it is possible to control the cavity mode spacing by controlling the group refractive index, n g (ν). The (real part of the) refractive index can be calculated from the ion absorption frequency distribution Although spectral hole-burning based slow light structures have been discussed previously [8,9] and slow light structures in general have been analysed extensively, e.g. Ref.…”

“…3b shows the corresponding data with a 3 MHz transmission window where the cavity round trip time is increased to well over a microsecond. The group velocity, v g , is approximately given by [8,10] …”

Slow light for deep tissue imaging with ultrasound modulation

“…This has so far prevented ultrasound modulated optical tomography from finding clinical applications. Here, we show that using slow light 3 in addition to a high performance spectral hole burning type filter 4 can finally reach this elusive goal. In particular, we show that ultrasound modulated light coming from deep inside an unprecedented 9 cm thick tissue phantom can be seen without detectable background.…”

“…Slow light naturally arises from the steep refractive index dispersion in the passband of a deep spectral hole (see Figure 2(d)). 4,18 Conversely, since the dispersion is relatively flat in the absorbing region several hole widths away, any untagged light leaking through the crystal is not significantly slowed. For an optical pulse whose spectral width is matched to that of the spectral hole passband, the delay measured in pulse widths will be proportional to the optical density in the surrounding absorbing region.…”

“…For an optical pulse whose spectral width is matched to that of the spectral hole passband, the delay measured in pulse widths will be proportional to the optical density in the surrounding absorbing region. 4 The quality of the data that can be obtained strongly depends on the filter characteristics (transmission, suppression, steepness, etc.) and extensive work has been investigated in optical pumping techniques important for the filter creation.…”