In this paper, dual-chirped arbitrary microwave waveform has been generated through photonics, incorporated with single dual parallel mach-zehnder modulator (DPMZM) inbuilt mach zehnder interferometer (MZI) structure. We have taken two cases of chirping i.e. linear and nonlinear chirps. A case of linear chirping has been explored previously. However, to the best of the authors' knowledge effect of nonlinear chirping in this paper is evaluated for the first time. Other photonics approaches are also available, such as spectra shaping and wavelength to time mapping. But due to fixed spectral response of spectral shaper, center frequency of linear chirp generated waveform is fixed. To get the large center frequency again we have to use large number of spectral shapers which will increase the system complexity. DPMZM avoids such difficulties. These MZMs are biased at the minimum transmission point to get carrier suppressed modulation. Product modulator (PM) is cascaded to the lower arm of DPMZM. Here by using DPMZM we get two advantages. First we have two complimentarily chirped microwave waveforms and second up conversion of the frequency of microwave carrier. A dual-chirped microwave waveform with centre frequency 6 GHz with bandwidth 200 MHz and 2 GHz is generated. The paper gives specific details about various performance parameters such as input signal frequency and power, output signal parameters viz output frequency, chirp rate, chirp bandwidth, time bandwidth product (TBW), etc. The overall model and its performance parameters are computed through MATLAB simulation.
1. Seeds, A. J., "Microwave photonics," IEEE Trans. Microwave Theory Tech., Vol. 50, No. 3, 877-887, Mar. 2002. doi:10.1109/22.989971
2. Seeds, A. J. and K. Williams, "Microwave photonics," J. Lightwave Technol., Vol. 24, No. 12, 4628-4641, Dec. 2006. doi:10.1109/JLT.2006.885787
3. Capmany, J. and D. Novak, "Microwave photonics combines two worlds," Nature Photonics, Vol. 1, 319-330, Sep. 2007. doi:10.1038/nphoton.2007.89
4. Richards, M. A., Fundamentals of Radar Signal Processing, 2 Ed., McGraw-Hill, New York, NY, USA, 2014.
5. Skolnik, M. I., Introduction to Radar Systems, 2 Ed., McGraw-Hill, New York, NY, USA, 2001.
6. Fitzgerald, R. J., "Effects of range-doppler coupling on chirp radar tracking accuracy," IEEE Trans. Aerosp. Electron. Syst., Vol. 10, No. 4, 528-532, Jul. 1974.
7. Amar, A. and Y. Buchris, "Asynchronous transmitter position and veloc-ity estimation using a dual linear chirp," IEEE Signal Process. Lett., Vol. 21, No. 9, 1078-1082, Sep. 2014. doi:10.1109/LSP.2014.2321330
8. Dotan, A. A. and I. Rusnak, "Method of measuring closing velocity by transmitting a dual-chirp signal," Proc. 26th IEEE Conf. Elect. Electron. Eng. Israel, 000258-000262, Eilat, Israel, Nov. 2010.
9. Zhu, D. and J. Yao, "Dual-chirp microwave waveform generation using a dual-parallel Mach- Zehnder modulator," IEEE Photonics Technology Letters, Vol. 27, No. 13, Jul. 1, 2015.
10. Iwashita, K., T. Moriya, N. Tagawa, and M. Yoshizawa, "Doppler measurement using a pair of FM-chirp signals," Proc. IEEE Symp. Ultrason., 1219-1222, Honolulu, HI, USA, Oct. 2003.
11. Middleton, R. J. C., D. G. Macfarlane, and D. A. Robertson, "Range autofocus for linearly frequency-modulated continuous wave radar," IET Radar, Sonar Navigat., Vol. 5, No. 3, 288-295, Mar. 2011. doi:10.1049/iet-rsn.2010.0097
12. Weigel, R., et al., "Microwave acoustic materials, devices, and applications," IEEE Trans. Microw. Theory Techn., Vol. 50, No. 3, 738-749, Mar. 2002. doi:10.1109/22.989958
13. Panasik, C. M., "Multiple frequency acoustic reflector array and monolithic cover for resonators and method,", U.S. Patent 6 441 703, Aug. 27, 2002.
15. Gomez-Garcia, D., C. Leuschen, F. Rodriguez-Morales, J.-B. Yan, and P. Gogineni, "Linear chirp generator based on direct digital synthesis and frequency multiplication for airborne FMCW snow probing radar," Proc. IEEE MTT-S Int. Microw. Symp. (IMS), 1-4, Tampa, FL, USA, Jun. 2014.
17. Khan, M. H., et al., "Ultrabroad-bandwidth arbitrary radiofrequency waveform generation with a silicon photonic chip-based spectral shaper," Nature Photon., Vol. 4, 117-122, Feb. 2010. doi:10.1038/nphoton.2009.266
18. Kanno, A. and T. Kawanishi, "Broadband frequency-modulated continuous-wave signal generation by optical modulation technique," J. Lightw. Technol., Vol. 32, No. 20, 3566-3572, Oct. 15, 2014. doi:10.1109/JLT.2014.2318724
19. Yao, T., D. Zhu, S. Liu, F. Zhang, and S. Pan, "Wavelength-division multiplexed fiber-connected sensor network for source local-ization," IEEE Photon. Technol. Lett., Vol. 26, No. 18, 1874-1877, Sep. 15, 2014.
20. Li, W. and J. P. Yao, "Microwave frequency multiplication using two cascaded Mach-Zehnder modulators," Proc. 2009 Asia-Pacific Microwave Photonics Conf., Beijing, China, Apr. 2009.
21. Li, W. and J. P. Yao, "Investigation of photonically assisted microwave frequency multiplication based on external modulation," IEEE Trans. Microw. Theory Tech., Vol. 58, No. 11, 3259-3268, Nov. 2010. doi:10.1109/TMTT.2010.2075671