Design of an all-optical fractional-order differentiator with terahertzbandwidth based on a fiber Bragg grating in transmission
2017
All-optical fractional-order temporal differentiators with
bandwidths reaching terahertz (THz) values are demonstrated with
transmissive fiber Bragg gratings. Since the designed fractional-order
differentiator is a minimum phase function, the reflective phase of the
designed function can be chosen arbitrarily. As examples, we first design
several 0.5th-order differentiators with bandwidths reaching the THz range
for comparison. The reflective phases of the 0.5th-order differentiators
are chosen to be linear phase, quadratic phase, cubic phase, and
biquadratic phase, respectively. We find that both the maximum coupling
coefficient and the spatial resolution of the designed grating increase
when the reflective phase varies from quadratic function to cubic function
to biquadratic function. Furthermore, when the reflective phase is chosen
to be a quadratic function, the obtained grating coupling coefficient and
period are more likely to be achieved in practice. Then we design
fractional-order differentiators with different orders when the reflective
phase is chosen to be a quadratic function. We see that when the designed
order of the differentiator increases, the obtained maximum coupling
coefficient also increases while the oscillation of the coupling
coefficient decreases. Finally, we give the numerical performance of the
designed 0.5th-order differentiator by showing its temporal response and
calculating its cross-correlation coefficient.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
26
References
8
Citations
NaN
KQI