Xiangdong Jin

Proposal for photonic quantization with differential encoding using a phase modulator and delay-line interferometers

A photonic quantization approach to implementing analog-to-digital conversion (ADC) in the optical domain with differential encoding employing a phase modulator and delay-line interferometers (DLIs) is proposed and demonstrated. In the proposed ADC system, the phase-modulated signal is sent to an array of DLIs that have identical time delay difference, but different phase shifts, which are employed to achieve quantization with differential encoding. A proof-of-concept experiment is performed. The quantization of a 10 GHz sinusoidal signal with a bit length of 4 is experimentally demonstrated.

A Compact Photonic Microwave Receiver Integrated with Dielectric Resonator Antenna

A novel structure for antenna-integrated photonic microwave receiver is proposed. The volume of the photonic microwave receiver can be greatly reduced by directly coupling a dielectric resonator antenna to the microdisk-based modulator. Simulation results show good performance for this structure.

Flattened Frequency Response Using Fiber Bragg Grating V-Shape Filter in Radio Over Fiber Links

A novel scheme for improving RF performance in radio-over-fiber (RoF) systems by using fiber Bragg grating (FBG) is demonstrated. The optical double-sideband (DSB) signal is sent through a fiber Bragg grating working as an optical V-shape filter. The FBG offers simultaneous suppression of the two sidebands and the optical carrier. The closer the sidebands are to the optical carrier, the more the sidebands are suppressed. In this way the detected radio frequency (RF) signal after a photodetector increases as the RF frequency goes higher. Both theoretical analysis and experimental results show that this effect can compensate for the RF gain loss in high frequency region due to the deteriorated performance of devices such as photodetectors and Mach-Zehnder modulators at higher frequency. A uniform system frequency response with fluctuation of no more than 2 dB is obtained from 1 GHz to 16 GHz.

A Two-Dimensional LiNbO3 Photonic E-Field Sensor Using Inclined Dipole Antennas

A novel integrated opto-electric sensor for detecting two-dimensional (2-D) electric field (E-field) vector utilizing two inclined dipole antennas on one lithium niobate (LiNbO3) substrate is proposed and demonstrated. Two tapered antennas with inclination angles of 45° and 135° are fabricated on different Mach–Zehnder interferometer (MZI) optical waveguides so as to induce local E-fields within antenna gaps to modulate optical waves for separately measuring two E-field components. Experimental results show that polarization directions of the two inclined antennas are orthogonal. The minimum detectable E-field strength is 1.56 and 0.90 V/m for two MZIs, and the fabricated E-field sensor has a wideband frequency response from 1 to 6 GHz with ±8-dB fluctuations. The proposed integrated LiNbO3 photonic E-field sensor has the potential of 2-D E-field vector measurement.

A Novel Scheme of Microwave Generation Based on Heterodyne Phase Locking of an OEO

A novel scheme of microwave generation based on heterodyne phase locking of an optoelectronic oscillator (OEO) is proposed and demonstrated. The oscillation signal of a dual loop self-injection-locking OEO (DSILOEO) is mixed with a voltage controlled crystal oscillator (VCXO) and its up-converted output is phase-locked by a reference source to develop a heterodyne phase-locked-loop. The DSILOEO has suppressed phase noise while its frequency fluctuation is cancelled out by the VCXO so that low phase noise and excellent long-term stability can be realized independently for microwave generation, which greatly increases the design flexibility. The experimental results show that the phase noise at 10-kHz offset carrier of -122 dBc/Hz and the Allan deviation of 1.6 × 10-12 are achieved.

Frequency-dependent noise figure analysis of continuous photonic time-stretch system

In this paper, the frequency-dependent noise figure of a continuous photonic time-stretch system is theoretically analyzed and experimentally demonstrated. Mathematic analysis discloses that the frequency-dependent noise figure in the continuous photonic time-stretch system is mainly owing to the dispersion-induced phase shift in the link. In the experiment, a completely continuous signal is reconstructed with time-interleaved joining of four sections of time-stretched signals from optical wavelength-division de-multiplexing channels. The result of the frequency-dependent noise figure property agrees well with that of theoretical analysis.