In this paper,we present a novel ultrashort pulse shaper based on complex-modulated long-period-grating coupler（CM-LPGC）.Temporal rectangular waveform with 2-ps full width at half maximum（FWHM） is obtained by transforming the input Gaussian pulse.Tolerances of the CM-LPGC-based shaper to various non-ideal excitation conditions and fabricating errors are investigated.Results confirm that CM-LPGC is stable and suitable for optical pulse shaping operation.
We propose a novel all-optical buffer and shaper based on the adjustable power transferring characteristics of the complex-modulated long-period-grating coupler(CM-LPGC)and the multiple circulations of the self-closed fiber loop.By turning on the external optical pumps,the signals can be stored by utilizing the nonreciprocal power transferring of the CM-LPGC.When the buffer time is satisfied,the signals can be extracted discretionarily by turning off the external optical pumps.In addition,by controlling the spectral bandwidth of the CM-LPGC,the temporal rectangular pulse can be obtained by re-shaping the Gaussian input signal.
We report experiments of ultraviolet （UV） communication based on spread-spectrum technique. Field measurements via online UV communication are conducted to compare the system performances with and without spectrum spreading. The results indicate that the spread-spectrum technique is capable of suppressing noise in UV atmospheric scattering channel and therefore improve the system performance evidently. Details of implementation are also provided to make the results useful for similar system design in research on optical wireless communications.
