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Brillouin Scattering Generated Slow Light
We demonstrate a technique for generating tunable all-optical delays in room-temperature single-mode optical fibers at telecommunication wavelengths using the stimulated Brillouin scattering process. This technique makes use of the rapid variation of the refractive index that occurs in the vicinity of the Brillouin gain feature. The wavelength at which the induced delay occurs is broadly tunable by controlling the wavelength of the laser pumping the Stimulated Brillouin Scattering (SBS) process, and the magnitude of the delay can be tuned continuously by as much as 25 ns by adjusting the intensity of the pump field. The technique can be applied to pulses as short as 15 ns. This scheme represents an important first step towards implementing slow-light techniques for various applications including buffering in telecommunication systems.
Observation of slow light via SBS in a room temperature optical fiber at telecommunication wavelengths. Temporal evolution of the Stokes pulses (with a gain parameter G =11) emitted from the fiber in the absence (dotted) and presence (solid) of the pump beam for (a) 63 ns long and (b) 15 ns long input Stokes pulses.
Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. M. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd, and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005). PDF
Raman Scattering Generated Slow Light
We demonstrate an all-optical tunable pulse delay scheme that utilizes the power-dependent variation of the refractive index that accompanies stimulated Raman scattering in an optical fiber. Using this technique, we delay 430-fs pulses by up to 85% of a pulse width. The ability to accommodate the bandwidth of pulses shorter than 1 ps in a fiber-based system makes this technique potentially viable for producing controllable delays in ultra-high bandwidth telecommunication systems.
Plots of gain and delay vs. pump power (top). Amplitude of the transformed interferograms for pulse delay changes of 0 fs, 135 fs and 370 fs (bottom). The delay of 370 fs is the maximum delay achieved with our setup.
J. E. Sharping, Y. Okawachi, and A. L. Gaeta, "Wide bandwidth slow light using a Raman fiber amplifier," Opt. Express 13 6092-6098 (2005). PDF
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