Fully On‐Chip Microwave Photonic Instantaneous Frequency Measurement System

Abstract

Microwave photonics (MWP) is an emerging field that studies the interaction between microwave and lightwave for myriad communication and information applications. Recently, new opportunity for MWP has emerged driven by the advances of integrated photonics. However, despite significant progress made in terms of integration level, a fully on‐chip MWP functional system comprising all the necessary photonic and electronic components, is yet to be demonstrated. Here, the status quo is broken and a complete on‐chip solution for MWP system is provided, by exploiting hybrid integration of indium phosphide, silicon photonics, and complementary metal‐oxide–semiconductor electronics platforms. Applying this hybrid integration methodology, a fully chip‐based MWP instantaneous frequency measurement (IFM) system is demonstrated. The unprecedented integration level brings great promotion to the compactness, reliability and performances of the MWP IFM system, including a wide frequency measurement range (2–34 GHz), ultralow estimation errors (10.85 MHz), and a fast response speed (≈0.3 ns). Furthermore, the chip‐scale MWP IFM system is deployed into realistic tasks, where diverse microwave signals with rapid‐varying frequencies at X‐band (8–12 GHz) are accurately identified in real‐time. This demonstration marks a milestone for the integrated MWP, by providing the technology basis for the miniaturization and massive implementations of various MWP systems.

Wideband High-Speed and High-Accuracy Instantaneous Frequency Measurement System

“…However, they have high frequency measurement errors of above ±100 MHz. Note that recently there are few reports on frequency measurement systems implemented using integrated photonic technology that have fast measurement times [33], [34]. They operated based on the original frequency-to-power mapping technique, which requires a pair of high-speed photodetectors.…”

“…The system output microwave signal powers are measured, which are used to construct an amplitude comparison function (ACF) for estimating the incoming microwave signal frequency. The integrated photonics based frequency measurement systems have an over 30 GHz frequency measurement range and root mean square errors of 755 MHz [33] and 10.85 MHz [34].…”

Photonic-Assisted Receivers for Instantaneous Microwave Frequency Measurement Based on Discriminators of Resonance Type

“…The best results in terms of measurement error were shown in [33] with full integration of the photonic-electronic part on the chip. There are also proposals for improving the efficiency of optical connections [64], heterogeneous integration to increase the compactness and scalability of the system [65], and reducing production costs by integrating low-noise transimpedance amplifiers with a photonic part on a monolithic platform [66].…”

“…For example, a ring with a gap of 300 nm had a Q-factor of 3974 and covered the frequency range of 0.5-35 GHz, and a second ring with a gap of 700 nm had a Q-factor of 25833 and covered the frequency range of 0.1-5 GHz. An additional improvement to system performance in terms of measurement accuracy can be achieved by integrating a laser, an electro-optical modulator, a microring resonator, and photodetectors into a single monolithic photonic chip, as demonstrated in Figure 21 [33].…”

“…The key differences between implementation methods lie in the choice of the physical effect and the resonance type discriminator, which are the basis of IFM implementation. According to the measurement method, there are systems based on a fiber Bragg grating (FBG) [23][24][25][26][27], FBG with a phase shift (PS-FBG) [28][29][30][31], an optical microring resonator (MRR) [32][33][34][35][36], stimulated Brillouin scattering (SBS) [4,[37][38][39][40] and Fano resonance [41].…”