Decoupling and one-time elimination of the timing skew in a time-demultiplexing photonic analog-to-digital converter for high-resolution wideband signal acquisition.

Temporal alignment between the demultiplexing signal and sampled signal for complex wideband signals greatly increases the difficulty of designing high-speed and high-resolution photonic analog-to-digital converters (PADCs). We present a vector description to decouple the timing skew from the phase frequency response in time-demultiplexing PADC. We demonstrate that the calibration can be optically implemented with true time delay effects and the broadband input can be one-time calibrated through several single-frequency signals. For verification, we configure out a 40 GSa/s PADC with eight-interleaved sub-channels. The timing skew-induced spurs across the whole Nyquist band are effectively suppressed, making the PADC acquire a wideband signal with 16 GHz instantaneous bandwidth. The spurious-free dynamic range (SFDR) is enhanced to ∼55 dB, and the effective number of bits (ENOB) is improved from ∼5.5 bits to ∼8 bits within 20 GHz. It is nearly 1 bit better than the recently reported time-demultiplexing PADC under the comparable input frequencies.

Low dark-current and high-photodetectivity transparent organic ultraviolet photodetector by using polymer-modified ZnO as the electron transfer layer.

In this Letter, a transparent organic photodetector (OPD) with a property of ultraviolet sensitivity is demonstrated by using an inverted architecture. A conjugated polymer of ploy [(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctyl)fluorene)] is introduced to modify the energy level and morphology between ZnO and organic optoelectronic material. As a result, at a wavelength of 350 nm and a bias of -1 V, the photodetectivity of 1012 Jones from both sides of the transparent device is obtained with a working area of 1 cm2. Moreover, an optical simulation is applied to analyze the optical electric field distribution inside the OPD.