Optical chopper for prospective communication systems

Figure 1. Schematic of the SiO2 microdevice incorporating the Fabry-Perot microfilter

The microscopic device creates discrete light pulses from a continuous laser radiation.

The chopper, based on quantum effects, may soon replace currently used mechanical devices.

Chief Research Associate of Pulkovo Astronomical Observatory and Kazan Federal University Vladimir Mostepanenko comments, “A perforated disc is installed in front of a laser beam. The disc rotates and thus creates discrete light pulses. To obtain pulses of equal periods, the disc must rotate with a very precise constant angular speed. If the angular speed changes slightly, the pulses will not be exactly identical.”

The research team, comprising Russian scientists Vladimir Mostepanenko, Galina Klimchitskaya, and Viktor Petrov, and Professor of Darmstadt Technical University Theo Tschudi, co-authored the paper in Physical Review Applied. Their device is based on the balance between Casimir and light pressures.

“Our quantum chopper is a Fabry-Perot microfilter,” continues Prof. Mostepanenko. “If a distance between mirrors L is equal to the half wavelength of the light incident on the microfilter, it starts exhibiting interesting properties (for visible light, L is between 200 and 400 nanometers). Under this condition, the light pressure in the Fabry-Perot microfilter significantly increases, which leads to the declination of the right mirror and to a decrease in Casimir pressure. As a result, the resonance condition in the microfilter breaks, and an accumulated laser radiation goes outwards as the pulses of transmitted light. In so doing, Casimir force returns the right mirror to its initial position, the conditions for the resonance re-emerge, and the whole process is repeated. That is to say, the balance between Casimir force and light pressure force, which are equal in magnitude but differ in sign, leads to the cyclic character of this device’s functioning.”

The device may help create periodical light pulses in optical communication systems. The main advantage of a quantum chopper is there are no mistakes arising from non-constant rotation speeds.

The Russian side is in charge of theoretical research, and the German colleagues perform experiments. Research results have been presented at two international conferences.

Optical Chopper Driven by the Casimir Force

G. L. Klimchitskaya, V. M. Mostepanenko, V. M. Petrov, and T. Tschudi

Source text: Larisa Busil

Translation: Yury Nurmeev