Efficient Photonic Beamforming System Incorporating a Unique Featured Tunable Chirped Fiber Bragg Grating for Application Extended to the Ku-Band

Microwave Photonic Array Radars

“…Different from the optical path switching method, which produces discrete time delays, the dispersion-based true time delay can be continuously tuned by changing the optical wavelength. Typical dispersive devices for true time delay include single-mode fibers, linearly-chirped FBGs [58], [59], photonic crystal fibers [60], and few-mode fibers [61]. Together with the wavelength division multiplexing technique, multiple microwave signals carried by different wavelengths can easily experience different time delays within the same dispersion media.…”

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.…”

“…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. Contrarily, wavelengthtuned transmission over media featuring chromatic dispersion, such as single-mode fiber [21,25,28] or linearly chirped Bragg gratings [22,24,27,30], provides a continuous delay setting, yet it requires a precise and stable optical source. Given the typically high bandwidth that is supported by optoelectronics, low RF carrier frequencies become more challenging since rather long delay lines or highly dispersive media are required.…”

Efficient 2D Optical Beamforming Network With Sub Partitioning Capability Based on Raised Cosine Chirped Fiber Grating and Mach-Zehnder Delay Interferometer

“…OBFN based on ring resonators (RRs) provides sufficient range of delay with the tuning optical carrier frequency [4], [5], but the cascading of numerous RRs may result in a large ripple in delay characteristics. In [6], [7], multiple number of chirp fiber Bragg gratings (CFBGs) were used to demonstrate a variable optical delay line. OBFN based on Polarization domain interferometers avoid the need for multiple numbers of CFBG using several polarization controllers [8].…”