Low-Distortion Long Variable Delay of Linear Frequency Modulated Waveforms

The impulse response of 500-MHz-wide, linear frequency modulated (LFM) waveforms is delayed and advanced by 50 ns using microwave-photonic processing. The delays are obtained through the application of a variable frequency offset to a single optical sideband using an acousto-optic modulator. The peak-to-sidelobe ratio (PSLR) and integrated sidelobe ratio (ISLR) of the processed impulse response functions are higher than 18 and 20 dB, respectively, for the entire range of delay and advancement. The ISLR is 14 dB better than that of corresponding previous demonstrations. The results provide, for the first time, 100-ns microwave-photonic delay variations of practical radar signals with a high fidelity that complies with application standards. The method is applicable to LFM waveforms of arbitrary bandwidths and central radio frequencies.

[1]  Robert J. Mailloux,et al.  Phased Array Antenna Handbook , 1993 .

[2]  R. Rotman,et al.  Submicrosecond Scan-Angle Switching Photonic Beamformer With Flat RF Response in the C and X Bands , 2008, Journal of Lightwave Technology.

[3]  Ivana Gasulla,et al.  Slow and Fast Light Effects and Their Applications to Microwave Photonics Using Semiconductor Optical Amplifiers , 2010, IEEE Transactions on Microwave Theory and Techniques.

[4]  Hugh Griffiths,et al.  Air and Spaceborne Radar Systems: an Introduction , 2001, The Aeronautical Journal (1968).

[5]  José Capmany,et al.  Microwave photonics combines two worlds , 2007 .

[6]  J. Khurgin,et al.  Microwave Photonic Delay Line With Separate Tuning of the Optical Carrier , 2009, IEEE Photonics Technology Letters.

[7]  Ivana Gasulla,et al.  Dynamic Microwave Photonic Filter Using Separate Carrier Tuning Based on Stimulated Brillouin Scattering in Fibers , 2010, IEEE Photonics Technology Letters.

[8]  O. Raz,et al.  Optically Controlled Low-Distortion Delay of GHz-Wide Radio-Frequency Signals Using Slow Light in Fibers , 2007, IEEE Photonics Technology Letters.

[9]  C. C. Wang,et al.  Nonlinear optics. , 1966, Applied optics.

[10]  N.A. Riza,et al.  Hybrid analog-digital variable fiber-optic delay line , 2004, Journal of Lightwave Technology.

[11]  J. Capmany,et al.  Broadband true time delay for microwave signal processing, using slow light based on stimulated Brillouin scattering in optical fibers. , 2010, Optics express.

[12]  Beatriz Ortega,et al.  Chirped fibre Bragg gratings for phased-array antennas , 1997 .

[13]  A. Zadok,et al.  Long Microwave-Photonic Variable Delay of Linear Frequency Modulated Waveforms , 2012, IEEE Photonics Technology Letters.

[14]  M.A. Piqueras,et al.  Optically beamformed beam-switched adaptive antennas for fixed and mobile broad-band wireless access networks , 2006, IEEE Transactions on Microwave Theory and Techniques.