title: Holographic method of cohering fiber tapped delay lines.
abstract: We propose, analyze, and demonstrate the use of a holographic method for cohering the output of a fiber tapped delay line (FTDL) that enables the use of fiber-remote optical modulators in coherent optical processing systems. We perform a theoretical examination of the phase-cohering process and show experimental results for a radio frequency (RF) spectrum analyzer that uses a lens to spatially Fourier transform the output of a holographically phase-cohered FTDL providing 50 MHz resolution and bandwidths approaching 3 GHz. Substantial improvements in bandwidth should be achievable with better fiber length-trimming accuracy and improvements in resolution can be obtained with longer fiber delay lines. We also analyze and demonstrate the use of a parallel holographic technique that compensates for polarization state scrambling induced by propagation through an array of single-mode fibers. Both the phase-cohering holography and the polarization fluctuation compensation can operate on hundreds of fibers in parallel, enabling both coherent optical signal processing with FTDLs and coherent fiber remoting of optically modulated RF signals from antenna arrays.
authors.affiliation: Optoelectronic Computing Systems Center, Department of Electrical and Computer Engineering, University of Colorado at Boulder, Boulder, Colorado 80309, USA. colice@colorado.edu
authors.forename: Max
authors.initials: M
authors.lastname: Colice
authors.forename: Ted
authors.initials: T
authors.lastname: Weverka
authors.forename: Gregory
authors.initials: G
authors.lastname: Kriehn
authors.forename: Friso
authors.initials: F
authors.lastname: Schlottau
authors.forename: Kelvin
authors.initials: K
authors.lastname: Wagner