Nuannuan Shi

Photonic approach to microwave frequency measurement with extended range based on phase modulation

We propose and demonstrate a photonic approach to instantaneous frequency measurement with an extended range based on phase modulation. In the measurement system, two optical wavelengths and two dispersion fiber segments are used to construct the frequency-dependent amplitude comparison functions (ACFs). Several ACFs can be utilized jointly to determine the microwave frequency without ambiguities beyond a monotonic region of the lone conventional ACF. The measurable range of microwave frequency can be extended and the accuracy can be improved by selecting an ACF with a large slope. The experimental results show that the errors are limited within ±140 MHz of a frequency measuremental range from 8 to 20 GHz.

Optical up-converted single-sideband generation using intensity modulators and fiber gratings

Abstract. A novel method is proposed for optical up-converted single-sideband (OSSB) signal generation in radio over fiber links, which can realize optical carrier reuse synchronously. The OSSB signal is generated in order to overcome the fiber dispersion problem by using two intensity modulators in combination with fiber gratings. With this up-conversion technique, a 25 GHz OSSB radio frequency signal is generated by mixing an intermediate frequency signal (5 GHz) and low frequency local oscillator signal (10 GHz). The signal is transmitted over 25 km standard single-mode fiber successfully. And the received signal error vector magnitude is 5.8% root mean square, with eye diagram widely open.

Proposal of simple Photonic Frequency up-conversion in direct modulation radio over fiber link utilizing nonlinear photodetection scheme

This paper presents a simple photonic frequency up-conversion system based on direct modulation radio over fiber (RoF) link which employs optical-microwave double-mixing scheme with a high-speed photodetector (PD). With this up-conversion technique, an intermediate frequency(IF) signal of 500MHz carrying 20Mbps quadrature phase shift keying (QPSK) vector signal is up-converted to 16GHz in the base station via standard single-mode fiber (SMF) transmission. The received 16GHz radio frequency (RF) signal is demodulated successfully with the error vector magnitude (EVM) of 8.34% rms. The proposed architecture is with the advantages of cost-efficiency, system operation efficiency and reliability.

A photonic instantaneous microwave frequency measurementwith improved range and accuracy

A novel technique for instantaneous frequency measurement of unknown microwave signal based on both phase modulation and intensity modulation is theoretically and experimentally demonstrated. Based on the output microwave power through dispersive fiber links, three amplitude comparison functions (ACFs) are established, which are combined to measure the frequency of input microwave signal with improved measurable range and accuracy. In the frequency estimation process, the measured calibration ACFs are utilized as the look-up table. The experiment results show that measurement error smaller than 200 MHz can be obtained for the frequency from 0.5 GHz to 20 GHz.

Optical up-conversion of single sideband signal using frequency quadrupling technique for radio over fiber system

This paper proposes a novel method for optical up-converted single-sideband (SSB) signal generation in radio over fiber link, capable of high tolerance of fiber chromatic dispersion induced carrier fading effect. The OSSB signal, is generated by utilizing one low-bandwidth intensity modulator (IM) under frequency quadrupling modulation scheme with low-frequency local oscillator (LO) signal and one low-bandwidth IM biased at the null point in combination with fiber grating. With this up-converted SSB technique, a 26 GHz optical SSB radio frequency (RF) signal is generated by mixing a low frequency local oscillator (LO) signal (5.5GHz) and an intermediate frequency (IF) signal (4 GHz) carrying 80 Mbps quadrature phase shift keying (QPSK) vector signal. The signal is transmitted over 45 km standard single-mode fiber (SMF) successfully and shows negligible dispersion-induced carrier suppression effect. The received signal error vector magnitude (EVM) is 13% rms and 15.7 % rms before and after transmission over 45-km SMF.

Optical upconversion of single sideband signal using low-cost radio-over-fiber system

A novel optical single-sideband (OSSB) signal generation with simultaneous IF signal up conversion technique is proposed to overcome the fiber dispersion problem. With this up-conversion technique, a high frequency OSSB signal is generated by using two low bandwidth intensity modulators in combination with fiber gratings. The low frequency local oscillator (LO) signal is modulated by employing frequency doubling technique or frequency quadrupling technique respectively. The OSSB radio frequency (RF) signal generated by mixing the intermediate frequency (IF) signal and low frequency local oscillator (LO) signal, is transmitted over standard single-mode fiber successfully. The received signal error vector magnitude (EVM) is 5.8% rms and 13% rms.

A photonic approach to microwave/millimeter-wave frequency measurement with extended range based on phase modulation

Instantaneous frequency measurement (IFM) of input unknown microwave signals is critical importance for modern radar warning receivers in the field of electronic warfare. The photonic techniques have attracted more and more attentions for IFM due to the advantages of wide bandwidth, low loss, light weight, and immunity to electromagnetic interference. In this paper, a photonic approach to IFM with extended range based on phase modulation is presented. In the proposed measurement system, two optical wavelengths and two segment dispersion fibers are used to construct the frequency-dependent amplitude comparison functions (ACFs). Several ACFs can be jointly utilized to determine the microwave frequency without ambiguities beyond a monotonic region of the conventional one ACF. Then the measurable range of microwave frequency can be extended and the accuracy can be improved by selection of ACF with large slope. The operation principle of the photonic approach is illustrated and the experiment results show that the errors are limited within ±0.15 GHz from 8 to 20GHz frequency measurement range.