Abstract
Flat-top sharp optical filters of gigahertz bandwidth are realized using stimulated Brillouin scattering (SBS). Pump chirp control of the SBS process enables versatile programming of the filter shape and bandwidth. The operating wavelength of the filters is tunable, and their frequency response is inherently aperiodic. Full widths at half maximum of 1.3-2.5 GHz are demonstrated, with a filtering selectivity up to 30 dB and an rms ripple of 0.5-1 dB. The filters are used to convert double sideband to single sideband (SSB) modulations for 1-GHz-wide linear-frequency-modulated (LFM) signals of arbitrary radio-frequency carrier. Such SSB modulation is highly instrumental for photonic implementations of true time delay, for example, in antenna beam-forming. The peak-side-lobe ratio of the processed LFM signal was -32 dB; its main lobe was broadened by only 4%. The integrated side-lobe ratio, which is limited by noise from spontaneous Brillouin scattering, was better than 21 dB, which is a sufficient value for most systems. The technique results in a large modulation index and does not lead to harmonic distortions.
Original language | English |
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Pages (from-to) | 2168-2174 |
Number of pages | 7 |
Journal | Journal of Lightwave Technology |
Volume | 25 |
Issue number | 8 |
DOIs | |
State | Published - Aug 2007 |
Externally published | Yes |
Bibliographical note
Funding Information:Manuscript received January 28, 2007; revised April 19, 2007. The work of A. Zadok was supported by a scholarship from the Israel Clore Foundation. The authors are with the Department of Interdisciplinary Studies, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel (e-mail: avinoamz@ post.tau.ac.il; [email protected]; [email protected]). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/JLT.2007.901336
Keywords
- Microwave photonics
- Optical modulation formats
- Optical signal processing
- Optical tunable filters
- Stimulated Brillouin scattering (SBS)