Deflection of ultra-slow light by the Earth's gravity on laboratory length scale

Raman Research Institute - Bangalore 560080, India

Corresponding author: nkumar@rri.res.in

Received: 26 February 2008
Accepted: 22 April 2008

Abstract

The high speed of light in vacuo together with the weakness of Earth's gravity rule out any experimental detection of gravitational deflection of light on the laboratory length scale. Recent advances in coherent nonlinear optics that produce ultra-slow light in highly dispersive media with group velocities down to 10² ms^-1, or even less, however, open up this possibility. In this work, we present a theoretical study for a possible laboratory observation of the deflection of such an ultra slow light in the highly dispersive medium under the Earth's gravity. Our general relativistic calculation is based on the Gordon optical metric modified so as to include dispersion. The calculated linear vertical deflection turns out to be ~ 0.1  mm for a horizontal traversal of 0.5 m and a group speed v_g ~ 10² ms^-1. Experimental realizability and some conceptual points involved will be briefly discussed.