Abstract
A new technique to design an all-fiber temporal differentiator that has a large bandwidth and an arbitrary differentiation order is proposed and investigated. The proposed temporal differentiator is a special fiber Bragg grating (FBG) that is designed by controlling its magnitude and phase responses with the discrete layer peeling (DLP) method. There are three important features of this technique: 1) the temporal differentiator has an arbitrary magnitude response and a controllable bandwidth; 2) the temporal differentiator can be designed and fabricated with an arbitrary differentiation order that is realized in a single FBG; 3) the required maximum index modulation of the FBG-based differentiator is largely decreased by using a Gaussian windowing function. The use of the proposed technique to design temporal differentiators with a differentiation order up to the fourth and with a bandwidth up to 500 GHz is studied. A proof-of-concept experiment is then carried out. A first- and a second-order temporal differentiator with a bandwidth of 25 GHz are experimentally demonstrated.
Highlights
With the rapid development of photonics technologies, the implementations of basic operations with optics have attracted great interests due to the high potential to increase the signal processing speed that is several orders of magnitude higher than that achievable by digital electronics
A temporal differentiator can be realized based on cross-gain modulation in a semiconductor optical amplifier (SOA) [6,7,8]
The reported temporal differentiators can be classified into two categories: incoherent optical differentiators that operate on the optical intensity of the input signal and coherent optical differentiators that operate on the complex field of the input signal
Summary
With the rapid development of photonics technologies, the implementations of basic operations with optics have attracted great interests due to the high potential to increase the signal processing speed that is several orders of magnitude higher than that achievable by digital electronics. A few fundamental all-optical operators, such as a photonic temporal differentiator and integrator, have been designed and practically realized [1,2,3,4,5]. A temporal differentiator is a basic operator that performs real-time differentiation of an optical signal in the optical domain. The reported temporal differentiators can be classified into two categories: incoherent optical differentiators that operate on the optical intensity of the input signal and coherent optical differentiators that operate on the complex field of the input signal. The differentiators reported in [6,7,8] are incoherent optical differentiators, and in [3,4,5,9,10,11,12,13,14,15] are coherent optical differentiators
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