Jia Ye

Photonic generation of triangular-shaped pulses based on frequency-to-time conversion.

An all-fiber approach to generate triangular-shaped pulses based on frequency-to-time conversion is proposed and demonstrated. Two filter modules that have sinusoidal spectral responses are cascaded to create a triangular-shaped optical spectrum. Through the frequency-to-time conversion in a dispersive fiber, periodic triangular pulses with the same shape as the optical spectrum are obtained. The repetition rate and pulse width of the generated signals can be tuned by adjusting the modulation rate and the dispersion value, respectively.

Comb filter with independently tunable wavelength spacing and bandwidth using cascaded variable differential group delay elements

An all-optical comb filter with independently tunable wavelength spacing and bandwidth (BW) is proposed. Using three cascaded variable differential-group-delay elements, we demonstrate theoretically and experimentally the tunability of the comb filter with >10 dB sidelobe reduction by adjusting three elements. The wavelength spacing is determined by the first filter module, while the sidelobe suppression ratio and the BW are defined by the middle and the last one, respectively.

Two-dimensionally tunable microwave signal generation based on optical frequency-to-time conversion

We propose and experimentally demonstrate an all-fiber-based approach to generate microwave signals with tunable frequency and pulse width. The adjustable optical power spectrum can be achieved using a spectrum shaper, consisting of a variable differential-group-delay element and a bandwidth-tunable optical filter. Through the frequency-to-time conversion in the dispersive fiber, the frequency and pulse width of the obtained microwave signals can be user defined by modifying the optical spectrum shape.

Pre-Distortion Compensation of Dispersion in APL Based on DSB Modulation

A simplified pre-distortion compensation scheme for dispersion-induced power fading in double-sideband analog photonic links is experimentally demonstrated. By properly tuning the bias of the dual-electrode Mach-Zehnder modulator and the relative phase difference between two input RF signals, the frequency response of a dispersive link can be controlled. Experimental results show that the power fading occurred at 13 and 15 GHz over SMF is fully compensated with an enhancement of ~15 dB in spurious-free dynamic range.

Photonic Generation of Microwave Phase-Coded Signals Based on Frequency-to-Time Conversion

An all-fiber approach to generate phase-coded microwave signals, based on spectral shaping and a frequency-to-time conversion, is proposed and experimentally demonstrated. A phase modulator cascaded by a filter module that has a sinusoidal spectral response is used to create a frequency-shifted optical spectrum. Microwave pulses with the same shape as the optical spectrum are obtained through frequency-to-time conversion in a dispersive fiber. The phase of the generated radio frequency signals can be continuously shifted by tuning the applied voltage on the optical phase modulator.

Photonic generation of impulse ultrawideband signals with switchable shapes and polarities based on frequency-to-time mapping.

A photonic approach to generate impulse ultrawideband (UWB) signals with switchable shapes and polarities based on the frequency-to-time mapping technique is proposed and demonstrated. UWB monocycle, doublet, and triplet signals with two polarities can be obtained by adjusting the switchable spectrum shaper.

Analysis for reflection peaks of multiple-phase-shift based sampled fiber Bragg gratings and application in high channel-count filter design

An analytical expression for calculating the reflection-peak wavelengths (RPWs) of a uniform sampled fiber Bragg grating (SFBG) with the multiple-phase-shift (MPS) technique is derived through Fourier transform of the index modulation. The new expression can accurately depict the RPWs incorporating various parameters such as the duty cycle and the DC index change. The effectiveness of the derived expression is further confirmed by comparing the RPWs estimated from the expression with the simulated reflective spectra using the piecewise uniform method. And the reflective spectrum has been well optimized by introducing the Gaussian apodization function to suppress the sidelobes without any wavelength shift on the RPWs. Then, a high-channel-count comb filter based on MPS is proposed by cascading two or more SFBGs with different Bragg periods but with the same RPWs. Noticeably, the RPWs of the new structured SFBG can also be accurately calculated through the expression. Furthermore, the number of spectral channels can be controlled by choosing gratings with specified difference Bragg periods.

Simultaneous transmission of multiple wireless services over fiber with reduced network complexities

We propose a scheme of a radio-over-fiber (RoF) network supporting the simultaneous transmission of radio frequency identification (RFID), Wi-Fi, and ZigBee services. All services share the same optical transmitter and receiver to reduce the network complexity. Error vector magnitude (EVM) values of 0.36%, 1.23%, and 0.25% can be achieved in the downlink for RFID, WiFi, and ZigBee signals, respectively. The corresponding EVM values in the uplink are 0.37%, 1.78%, and 0.29%, respectively. The scheme is verified over a 2 km RoF link where RFID, WiFi, and ZigBee master nodes can communicate normally with their slave nodes.

Tunable Microwave Photonic Temporal Signal Processor: Differentiator and Integrator

A scheme for a multi-functional photonic assisted temporal signal processor is proposed using a tunable modulation module inside a time-spectrum convolution system. Both the first-, second-order differentiation and intensity integration are experimentally demonstrated. The differential and integral signals of two input signals are successfully obtained by adjusting a band-pass optical filter and a polarization controller.

PDM RZ-to-NRZ and NRZ-to-PRZ format conversions using a variable DGD element inside a polarization-diversified loop

A novel scheme for bit-rate-variable polarization-division-multiplexed return-to-zero to nonreturn-to-zero and NRZ to pseudo-return-to-zero format conversions is proposed using a variable differential-group-delay element inside a polarization-diversified loop. Conversion for both 2×10 and 2×12.5 Gbit/s PDM signals are successfully demonstrated with approximately 1 dB additional power penalty by properly adjusting DGD values of the variable DGD element.