Photonic true time delay beamforming technique with ultra-fast beam scanning

Abstract

A photonic-based true time delay (TTD) phased array antenna (PAA) with ultra-fast angle scan is proposed and experimentally demonstrated. A tunable TTD is realized using a wavelength-swept laser and an array of dispersive elements. The key novelty of our work is the ultra-fast angle scan using an ultra-fast wavelength-swept laser source, which is constructed by a gated multi-wavelength laser (MWL) and a dispersion compensation fiber (DCF). In our experiments, a wavelength-sweep time between two adjacent wavelengths is only several nanoseconds for wavelength spacing of 2.4, and 3.2 nm. We successfully realized an ultra-fast angle scan from 0 to 43° with a step of 8.8° in 12.48 ns.

Advanced RF and microwave functions based on an integrated optical frequency comb source

“…For microwave and RF time delays a diverse range of photonic approaches has been proposed based on dispersive elements such as single-mode fibre [12], dispersion compensating fibre [13] and fibre Bragg gratings [14][15], slow-light devices based on stimulated Brillouin scattering, integrated resonators [16][17][18], wavelength conversion coupled with chromatic dispersion [19], and many more [20][21]. Approaches based on switchcontrolled dispersive recirculating loops [22], fast sweeping lasers [23], and dispersion-tunable media [24] have also been investigated. Photonic RF and microwave devices featuring delay-line (i.e., transversal) structures require multiple channel RF time delays.…”

“…Photonic RF and microwave devices featuring delay-line (i.e., transversal) structures require multiple channel RF time delays. Traditionally, this has been achieved via discrete laser arrays [16,[22][23][24] or FBG arrays [14][15], which, although offering advantages, have resulted in significantly increased complexity, as well as reduced performance due to a limited number of optical wavelengths and other factors. Alternative approaches, including those based on optical frequency comb (OFC) sources [12], can mitigate this problem, although they too can suffer from drawbacks such as the need for cascaded high frequency electro-optic (EO) [2,[25][26][27][28][29][30] and Fabry-Perot EO [31] modulators that in turn require high-frequency RF sources.…”

Analog Coherent-Optical Mobile Fronthaul With Integrated Photonic Beamforming

“…There are many principles that can be exploited for realizing a TTD in the optical domain. Differential delays can be introduced through spatial switching or tuning of the propagation path [11][12][13][14][15][16][17][18][19][20] or transmission over a dispersive medium for which its wavelength-dependent dispersion slope suffices the required amount of phase delay [21][22][23][24][25][26][27][28][29][30]. Switched binary delays realized through fiber-optic [12,14,19,20,23] or waveguide-based delay lines [31,32] lead to a discretization of the obtained delay, which is an undesired characteristic for 5G beamforming.…”

True Time Delay Optical Beamforming Network Based on Hybrid InP-Silicon Nitride Integration

“…Microwave photonics have been in the research spotlight thanks to their ability to offer equal or even superior performance compared to the electrical beamforming networks and support ultra-wideband operation, with lower power consumption and immunity to electromagnetic interference [3]- [4]. Initial efforts involve mainly implementations of true time delay (TTD) optical beamforming networks (OBFNs) based on fiber segments of various length [5]- [6], multi-core [7]- [8] and highly dispersive fibers [9]- [10], fiber Bragg gratings [11]- [12], spatial light modulators [13]- [14], micro-optics [15]- [17], and semiconductor optical amplifiers [18]- [19]. In addition, implementations that approximate the TTD operation using optical phase shifters have also been proposed [20]- [21].…”