Continuously-tunable microwave photonic true-time-delay based on a fiber-coupled beam deflector and diffraction grating

Abstract

This paper reports the demonstration of a continuously-tunable true-time delay line for microwave photonics and optical communications capable of high-resolution phase control throughout the 1-100 GHz modulation range. A fiber-coupled device is demonstrated with 75 ps of continuous delay tuning range, 3 dB optical insertion loss, and minimal RF amplitude and phase variation over the 4-18 GHz band. Measured delay ripple was less than 0.2 ps. Theoretical analysis is also presented which indicates scalability to delay tuning ranges over 1000 ps and modulation bandwidths over 10 THz.

Photonic methods for RF phase shifting

“…1(a). This configuration differs from that reported previously (and described in detail in [3]) in that an acousto-optic beam deflector was utilized for rapid beam deflection, and a focusing mirror was used to reduce device length. In its operation, the output of a single-mode optical fiber was imaged into an acousto-optic (AO) beam deflector cell, which allowed the beam deflection angle to be controlled via a tuning voltage V T .…”

Silicon integrated microwave photonic beamformer

“…A continuous-wave (CW) light at the 1544.1 nm wavelength was adjusted to TE polarization by a polarization controller (PC) before it was coupled to the modulator. The modulator driving signal is a 2 23 -1 pseudo-random binary sequence (PRBS) non-return-to-zero (NRZ) signal, generated by a pulse pattern generator (PPG). In the measurement, the modulator was biased at 0 V. The modulated optical signal was amplified by an erbium-doped fiber amplifier (EDFA) followed by a band-pass filter to suppress the amplified spontaneous emission (ASE) noise.…”

“…The outstanding performances of photonics-assisted radars have opened intense research interest ranging from fundamental study to practical applications. A variety of optical beamforming network (OBFN) systems with different kinds of OTTDLs have been proposed, based on highly-dispersive fibers [11][12][13], fiber Bragg gratings [14,15], microcombs [16,17], dense wavelength division multiplexers [18], fast scanning lasers [19], and free-space optics [20][21][22][23]. They are mainly focusing on OTTDLs with both large tuning range and fine-tuning resolution.…”

Microwave photonics: radio-over-fiber links, systems, and applications [Invited]

“…In general, MWP uses the strength of photonic techniques to generate, distribute, process, and analyze microwave signals. Because of the inherent properties of photonics, such as low loss transmission, there has been an increasing effort to develop MWP techniques for different applications, including broadband wireless access networks [7], satellite communications [8], optical signal processing [9], electronic warfare systems [10], and optical coherence tomography techniques [11]. Many of these application areas demand ever-increasing values for speed, bandwidth, and dynamic range while at the same time requiring devices that feature small size, lightweight and low-power performance, large tenability, and strong immunity to electromagnetic interference.…”