Photonics-based multi-band linearly frequency modulated signal generation and anti-chromatic dispersion transmission

Abstract

A photonics-based anti-chromatic dispersion transmission scheme for multi-band linearly frequency modulated (LFM) signals is proposed and experimentally demonstrated. In the central station (CS), the key component is an integrated dual-polarization quadrature phase shift keying (DP-QPSK) modulator, of which the up-arm and down-arm are driven by a microwave reference signal and an intermediate-frequency (IF) LFM signal respectively. By properly adjusting the DP-QPSK modulator, optical frequency comb (OFC) and frequency shift lightwave are generated. After polarization coupling and remote transmission, the orthogonal-polarization optical signals are introduced into balanced photodetector for heterodyne detection. Thence, multi-band LFM signals are generated and transmitted to remote base stations (BS) with the largest power for the anti-chromatic dispersion ability. Experiments are conducted to verify the analysis. Multi-band LFM signals at L (1.5 GHz), C (7 GHz), X (10 GHz), Ku (15.5 GHz) and K (18.5 GHz) bands with flatness of 1.9 dB are simultaneously obtained in the CS after 50 km fiber transmission, while the normally double-sideband modulation approach experiences a significant power fading for the fiber dispersion. Tunability of the system is evaluated, and detection performances of the generated signals are also analyzed.

Photonic generation of dual-band complementary linearly chirped microwave waveforms based on phase modulator

“…Photonic-assisted chirped waveforms generation is one of the key techniques in the advanced radar systems, and many microwave photonic schemes have been reported 8 – 22 In Refs. 8–11, the linearly chirped microwave waveforms are generated with increased time-bandwidth product (TBWP) by the external modulation.…”

Photonic Generation and Transmission of Dual-Band Dual-Chirp Microwave Waveforms at C-Band and X-Band With Elimination of Power Fading

“…In these schemes, a multi-wavelength light source or an additional modulator was used to generate the required OFC. In [16], [17], a polarization-division multiplexing modulator was used to generate the OFC and load a baseband chirped signal at the orthogonal polarization states. The above mentioned OFC-based method can generate multi-band dual-chirp microwave signals thanks to the large number of the comb lines of the OFC.…”

“…The above mentioned OFC-based method can generate multi-band dual-chirp microwave signals thanks to the large number of the comb lines of the OFC. However, a high power RF signal is needed in [16], [17] to generate the OFC, which leads to high power consumption. In addition, dual-chirp signals generated by double sideband modulation suffer from periodical power fading due to the chromatic dispersion in long distance fiber transmission [18].…”

“…In addition, dual-chirp signals generated by double sideband modulation suffer from periodical power fading due to the chromatic dispersion in long distance fiber transmission [18]. In [17], single sideband modulation was used to overcome the power fading effect by using a 90° hybrid coupler, but the frequency range of the generated chirped waveforms was restricted by the 90° hybrid coupler. Moreover, the frequency intervals of the generated dual-chirp waveforms in different bands in the above mentioned methods are determined by the frequency spacing of the OFC, which have the fixed multiple factor relationship between different bands.…”

Multi-Functional Microwave Photonic Radar System for Simultaneous Distance and Velocity Measurement and High-Resolution Microwave Imaging

“…especially the linearly frequency-modulated (LFM) signals [19]- [21]. Based on these technologies, some photonics-based distance and velocity measurement methods have been presented [22]- [24].…”