In this paper, a multi-passband microwave photonic filter (MPF) based on multiple dispersive devices has been proposed and experimentally demonstrated. The Mach-Zehnder interferometer (MZI) divides the broadband light source (BBS) into multiple optical taps, and with the combination of different dispersion mediums such as chirped fiber Bragg grating (CFBG) and single mode fiber (SMF) to delay the optical tap, a MPF with multiple passbands can be simply achieved. The number of the passbands can be easily controlled by changing the number of the dispersion medium. In the experiment, the frequency response result of the four passbands is obtained by accessing two CFBGs and two SMFs. In addition, by adjusting the wavelength interval of the interference spectrum with a variable optical delay line (VODL), all passbands of the filter can be simultaneously tuned. The filter has broad application prospects in the fields of modern wireless and satellite communication, optoelectronic oscillator and optical sensing.
In this paper, a tunable dual-bandpass microwave photonic filter (MPF) based on a single broadband light source (BBS) has been proposed and experimentally demonstrated. By cascading two chirped fiber Bragg gratings (CFBG) with different reflection bandwidth and chirp parameter, the different delay of the modulated light signal in the system is introduced and consequently, a MPF with two different passbands can be realized. Two different passbands with the frequency of 6.75 GHz and 16.01 GHz is obtained in the experiment. By changing the free spectral range (FSR) of the Mach Zehnder interferometer (MZI) through an optical tunable delay line (OTDL), the central frequency of the two passbands can be changed. The dual-bandpass MPF presented in this paper is easy to implement and has good tunability and stability.
A Ka-band microwave photonic imaging radar demonstrator with 10.02 GHz-bandwidth is proposed and experimentally demonstrated. Continuous linear frequency waveform is optically generated in the transmitter and processed in the receiver. The range resolution of the demonstrator is tested to be 1.68 cm. Out-field tests while demonstrator works at inverse synthetic aperture radar (ISAR) and synthetic aperture radar (SAR) mode are carried out to image different targets.