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Stark Modulator Based on Quantum State Mixing

IP.com Disclosure Number: IPCOM000088773D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Grischkowsky, DR: AUTHOR [+2]

Abstract

Ultraviolet light is difficult to modulate because of the lack of good electro-optic crystals in this spectral region. A low-voltage Stark modulator is described which operates on the principle of quantum state mixing and which is capable of picosecond switching of ultraviolet light beams.

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Stark Modulator Based on Quantum State Mixing

Ultraviolet light is difficult to modulate because of the lack of good electro- optic crystals in this spectral region. A low-voltage Stark modulator is described which operates on the principle of quantum state mixing and which is capable of picosecond switching of ultraviolet light beams.

It has been demonstrated that mixing of quantum states with different parity occurs when high Rydberg states are subjected to relatively small electric fields. Fig. 1 is a generalized energy level diagram. The transition between states |1> and |2> is initially forbidden by quantum mechanical selection rules, i.e., the matrix element <1|p|2> equals zero where p is the electric-dipole moment operator. However, when a modest electric field (typically 20 V/cm) is applied to the high Rydberg states, mixing of states occurs and the D state |1> is no longer a pure D state but contains a mixture of P states as well. The quantum mechanical selection rules, therefore, break down when the field is applied and the matrix element <1|p|2> no longer equals zero. It is thus possible to switch the absorption line off and on with an electrical signal.

In Fig. 2 an input narrow-line ultraviolet beam is tuned to the frequency, (omega(1) - omega(2)), of the indicated transition. If no voltage is applied to the Stark cell, the beam passes through the cell unattenuated. However, when a Stark voltage is applied, state mixing occurs and the beam is attenua...