Image-reject radio frequency (RF) receiver is the backbone of modern RF systems, but often suffers from limited bandwidth, local oscillator (LO) leakage, even-order distortion and I/Q imbalance. A wideband photonic image-reject RF receiver based on two phase-modulators (PMs) in a Sagnac loop and an I/Q balanced detector is proposed. In the experiment, excellent I/Q amplitude balance (<0.8 dB) and phase balance (<0.7 degrees) over a wide operating frequency from 8 to 40 GHz are achieved. Due to balanced detection, the even-order distortion and dc-offset are significantly suppressed. Combined with an analog intermediate frequency (IF) quadrature coupler, the image-reject RF receiver is implemented with a spurious free dynamic range (SFDR) of 99.4 dBHz2/3 and an image rejection of 50.3 dB. An antenna remoting RF vector signal with image interference is down-converted to the IF domain. Benefiting from the significant image rejection and Sagnac loop architectonics, a good constellation diagram and a low error vector magnitude (EVM) of the desired signal are obtained.

Microwave frequency-hopping signal generation is one of the backbone components in modern wireless communication system. In this paper, we propose a novel photoelectric integrated approach to implement broadband microwave frequency-hopping signal generation. The coherent dual optical combs are constituted by two Mach Zehnder modulators (MZMs) and one acousto-optic frequency modulator (AOM). By using dense wavelength division multiplexing (DWDM) and single-sideband modulation with carrier suppression, the proposed method extends the input signal's frequency hopping bandwidth by six times. Due to the photoelectric hybrid structure, the proposed method can achieve precise control for using electronic technology while also providing the advantages of high bandwidth and reconfigurability through photonics. In the experiment, the frequencies of generated signals can hop ranging from 0 to 6GHz. Meanwhile, the frequency hopping signals can maintain a well signal quality with the EVM lower than 6.4%.

An ultra-compact broadband silicon polarizing beam splitter is proposed based on a tilted nano-grating structure. A light cross coupling can be realized for transverse-magnetic mode, while the transverse-electric light can almost completely output from the through port. The length of the coupling region is only 6.8 μm, while an extinction ratio of 23.76 dB can be realized at a wavelength of 1550 nm. As a proof of concept, the device was fabricated by a commercial silicon photonic foundry. It can realize a 19.84 dB extinction ratio and an 80 nm working bandwidth with an extinction ratio of larger than 10 dB. The presented device also shows a good fabrication tolerance to the structure deviations, which is favorable for its practical applications in silicon photonics.

Integrated microwave photonics (MWP) is a fast growing area where high frequency microwave signals are processed in the optical domain, merging key advantages of both microwave photonics and photonic integrated circuits (PICs) technologies including low-loss, reconfigurability, advanced functionality, enhanced stability, and reduced footprint. Plenty of functionalities have been demonstrated in integrated MWP, especially based on spectral shaping technique, where the phase and amplitude of the optical spectrum is precisely tailored by PICs. However, on-chip linearization is lagging behind and has not been investigated deeply. It is crucial and urgent to study on-chip linearization methods, which will lead to advanced integrated MWP systems with large spurious-free dynamic range (SFDR). In this paper, we present two novel techniques for on-chip linearization of microwave photonic links. The first technique is based on line-by-line complex spectral shaping using a series of ring resonators. The second technique relies on spatial separation to achieve parallel spectral shaping in two complementary spatial channels. Both methods are demonstrated in low-loss programmable silicon nitride circuits that can already host a number of advanced functionalities. Our results point to the great potential of integrating advanced functionalities and linearization in the same integrated platform.

To improve the steering precision and angular resolution of liquid-crystal optical phased array, in this paper, we proposed a modified periodic phase controlled method to realize a continuous scanning with a constant angular resolution of less than 20 μrad, meanwhile, its precision is less than 5 μrad (rms). Also, another method we proposed is called subaperture coherence that can realize even better angular resolution less than 5 μrad, which is the limitation of our measurement instrument.