We propose and demonstrate an optically tunable photonic fractional temporal differentiator using a tilted fiber Bragg grating written in an erbium/ytterbium (Er-Yb) co-doped fiber. Thanks to the high absorption of the Er-Yb co-doped fiber, when it is pumped the refractive index is changed, and thus the phase of a cladding mode resonant wavelength is changed continuously by continuous tuning of the pumping power. By locating the wavelength of the input light wave at the location of a cladding mode resonant wavelength, a temporal differentiator with a tunable fractional order is achieved. The proposed technique is experimentally evaluated. A temporal differentiator with a tunable fractional order is demonstrated. The use of the fractional differentiator to implement temporal differentiation of a Gaussian pulse with a bandwidth of 28 and 75 GHz is also demonstrated.

Optical signal processing, tilted fiber Bragg grating (TFBG), tunable ultrafast fractional differentiator
IEEE Photonics Technology Letters
Department of Electronics

Shahoei, H. (Hiva), Albert, J, & Yao, J. (Jianping). (2012). Tunable fractional order temporal differentiator by optically pumping a tilted fiber Bragg grating. IEEE Photonics Technology Letters, 24(9), 730–732. doi:10.1109/LPT.2012.2187331