Implementation of Photonic True Time Delay Using High-Order-Mode Dispersion Compensating Fibers

Abstract

Abstract-We demonstrate the advantageous use of highly dispersive ( 450 ps nm km), high-order-mode (HOM) fiber modules for true time delay applications. Along with their low insertion loss, very low phase ripple (root mean square 0 3 over 0-20 GHz), and high immunity to nonlinear effects, the high dispersion values facilitate the construction of devices with relatively short fibers, resulting in improved tolerance of the radio frequency delay to thermal changes. The implications of multiple path interference effects in HOM modules are also studied and shown to be very small.

Tunable true-time delay of a microwave photonic signal realized by cross gain modulation in a semiconductor waveguide

“…Since the demonstration of an optically steered phased array antenna in 1991, 1 the study of tunable microwave time delay lines realized by photonics has become a hot topic within the developing research area of microwave photonics. 2 A common scheme exploits dispersion, with the time delay being varied by tuning the laser wavelength and propagating through high dispersion fibers 3,4 or chirped fiber gratings. [5][6][7] This scheme is, however, relatively bulky and complex.…”

Simplified WDM optical beamforming network for large antenna arrays

“…In addition to these components, other devices are needed, for example, one external modulator or a dispersive medium, but these do not scale with the number of antenna elements. The number of photodiodes also scales with the size of the antenna array but their number is the same in this and previous architectures [5]- [7] since they are needed to convert the signals from the optical to the electrical domain. Fig.…”

“…In optical beamforming networks based on several optical carriers and a dispersive medium a correspondence is established between each optical carrier and each antenna element [5]- [7]. However, it is feasible to reduce the number of optical sources of the architecture if the optical carriers are reused by means of the combination of dispersive and nondispersive time delays.…”

“…Fig. 3 compares the number of components needed using the proposed technique with previous WDM beamforming architectures [5]- [7]. Fig.…”

Tunable true-time delay unit based on Opto-VLSI processing

“…Several approaches have been used to realise tunable true-time delay units, including the use of free-space [6], in-fiber bragg gratings (FBGs) [3], integrated optical waveguides [7], optical-switch-based n-bit TTD [8], dispersion-enhanced photonic-crystal fibers [9], and higher-order mode dispersion in multi-mode fibers [10].…”