A temporal convolution system for the short-time Fourier transformation (STFT) of an electrical signal based on a bidirectional chirped fiber Bragg grating (CFBG) is proposed and experimentally demonstrated. In this system, the electrical signal to be analyzed is applied to an electro-optical modulator to simultaneously modulate the temporal waveform and the spectrum of a time-stretched optical pulse, which is generated by a mode-locked laser and dispersed by a CFBG. The modulated optical signal is filtered to be several parts, added with separate time delays and sent to the other port of the same CFBG. Thus the optical signal is temporally recompressed and the spectrum of the electrical signal is able to be mapped into the time domain. The bidirectional CFBG realizes exactly complementary dispersion value for the optical pulse propagating in two opposite directions, which guarantees an optimal frequency resolution of the STFT system. An STFT experiment for a microwave signal with four different frequencies at 5 GHz, 10 GHz, 15 GHz and 20 GHz has been demonstrated.
KEYWORDS: Extremely high frequency, Photonics, Radar, Signal generators, Signal detection, Radar signal processing, Signal processing, Wireless communications
Multifunctional integration of electronic equipment is a main development trend in the future, wherein the integrated signal generation enables a key part. Therefore, it is of great significance to develop the generation of anti-jamming joint radar-communication (JRC) signal. Here, a photonics-assisted generation scheme of millimeter-wave (MMW) anti-jamming JRC signal is proposed. A large-bandwidth MMW dual-band agile JRC signal is generated based on a photonic MMW up-conversion and frequency permutation techniques. Meanwhile, thanks to the dual-band photonic radar de-chirping combined with coherent fusion method and low-cost communication self-coherent reception, the high resolution radar detection and communication with large amount of information are realized simultaneously. In the photonics-assisted JRC simulation system in W-band, a dual-band agile stepped-linear frequency modulation JRC signal covering 81-93 GHz is generated. Moreover, through a dual-band coherent fusion processing, the dual-band signals occupying with only a bandwidth of 2 GHz are successfully fused into an equivalent ultra-wideband signal with a bandwidth of 12 GHz, enabling a radar ranging with a resolution of 1.26 cm. Using a low-cost self-coherent reception, an anti-jamming wireless communication with factorial 10 is demonstrated, which can achieve up to 21.8 bits quantity of information.
A multi-beam optical beamforming network with low loss is proposed based on the integrated arrayed waveguide grating (AWG). By using the diffraction effect of AWG, the optical multiple beamforming architecture is reduced significantly since the true time delays for different wavelength can be realized simply by employing only one module. The 3 channels of 88 AWG for dense wavelength division multiplexing (WDM) with low loss is fabricated successfully, and then the integrated optical multiple beamformer for eight-element is demonstrated. Experimental results show that the insertion loss for each beamformer is reduced to 5.64 dB. Furthermore, the number of simultaneous beamformer achieves to be 4, which could cover the airspace from -36° to 18°.
Graphene has become a promising nonlinear optical medium due to its ultra-high nonlinear coefficients and tight light mode confinement ability. By optimizing the geometry parameters, a 3.9-mm-long graphene-covered silicon ridge waveguide is demonstrated, resulting in a maximum bandwidth of 498 nm and a peak conversion efficiency of -15.2 dB in mid-infrared band, with the pump power of 1 W. The results in this article show that graphene has unparalleled potential in the field of nonlinear optics.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.