Discrete-time optical Processing of microwave signals

Abstract

We propose and experimentally demonstrate new architectures to realize multi-tap microwave photonic filters, based on the generation of a single or multiple dynamic Brillouin gratings in polarization maintaining fibers. The spectral range and selectivity of the proposed periodic filters is extensively tunable, simply by reconfiguring the positions and the number of dynamic gratings along the fiber respectively. In this paper, we present a complete analysis of three different configurations comprising a microwave photonic filter implementation: a simple notch-type Mach-Zehnder approach with a single movable dynamic grating, a multi-tap performance based on multiple dynamic gratings and finally a stationary grating configuration based on the phase modulation of two counter-propagating optical waves by a common pseudo-random bit sequence (PRBS).

Theory of Optical-Filtering Enhanced Slow and Fast Light Effects in Semiconductor Optical Waveguides

“…The microwave phase shift induced by SOA is determined by (13) Thus, based on the semi-analytical solution and different optical filtering schemes, the corresponding phase shift and ac power depends differently on the complex amplification , the linewidth enhancement factor as well as the inputopticalsignal , .Inparticularwenoticethatfor the usual case where both sidebands are detected the phase shift does not dependon the -factor, i.e.,the dynamics of the refractive index does not influence the phase of the envelope. Thisisinagreementwith [5]whereitwasshownalsothatthis case can be analyzed by considering the dynamical effects of gain saturation.…”

“…When the modulation frequency is in the microwave region, such signals form the basis of microwave photonics [13], where a phase shifter is a much desired functionality. From an application point of view, it is thus of significant interest to realize an optically fed microwave phase shifter based on semiconductor devices with a variable phase shift range of at gigahertz frequencies.…”

Opto-VLSI-based reconfigurable photonic RF filter

“…Several tunable photonic RF filter structures have been proposed and demonstrated [1][2][3][4][5][6]. In these demonstrations, filter reconfigurability is achieved by adjusting the tap weights through optical attenuation via MEMS switches [2], using variable optical attenuators (VOAs) [4], or employing Fiber Bragg Gratings (FBG) [5] that can be tuned either thermally or mechanically.…”

“…In these demonstrations, filter reconfigurability is achieved by adjusting the tap weights through optical attenuation via MEMS switches [2], using variable optical attenuators (VOAs) [4], or employing Fiber Bragg Gratings (FBG) [5] that can be tuned either thermally or mechanically. However, in order to achieve high-resolution reconfigurable photonic RF signal processors that are able to synthesise arbitrary transfer characteristics, extensive research and development are still needed [6].…”

Exploring carrier dynamics in semiconductors for slow light

“…Practical applications, e.g. within microwave photonics [2] and optical communications, favour a technology which allows cheap and compact devices with potential for integration and recent results on semiconductor waveguides indicate a strong potential [3][4][5][6][7][8][9][10][11]. Fig.…”