Lab-on-a-chip systems are currently one of the most promising areas in the development of ultra-compact sensor systems, used primarily for gas and liquid analysis to determine the concentration of impurities. Integrated photonics is an ideal basis for designing “lab-on-a-chip” systems, advantageous for its compactness, energy efficiency, and low cost in mass production. This paper presents a solution for “lab-on-a-chip” device realization, consisting of a sensor and an interrogator based on a silicon-on-insulator (SOI) integrated photonics platform. The sensor function is performed by an all-pass microring resonator (MRR), installed as a notch filter in the feedback circuit of an optoelectronic oscillator based on an electro-optic phase modulator. This structure realizes the frequency interrogation of the sensor with high accuracy and speed using a conventional single-mode laser source. The system sensitivity for the considered gases is 13,000 GHz/RIU. The results show that the use of frequency interrogation makes it possible to increase the intrinsic LoD by five orders. The proposed solution opens an opportunity for fully integrated implementation of a photonic “laboratory-on-a-chip” unit.

The article describes an approach to simulating a microring resonator structure on the silicon nitride integrated photonics platform when exposed to various hazardous to human health gases. We simulated various gases by changing the refractive index of the medium surrounding the resonator from 1 (vacuum) to 1.001768 (CCl₄). The microring structure resonant wavelengths varied for various gases, and the quality factor, sensitivity, and intrinsic detection limit were determined. The simulation results show that it is possible to detect a wide range of gases hazardous to human health, including carbon tetrachloride, mercury vapor, carbon monoxide, and nitrogen monoxide, using the developed sensor. However, it is impossible to distinguish the last two gases based on the results of the current work using the SiN platform. Coatings are one of the potential ways to improve the designed sensor for detecting these gases.

This article analyzes the influence of the accuracy of manufacturing microring resonators on the characteristics of sensors based on silicon-on-insulator and silicon nitride platforms of integrated photonics. We estimated a deviation of 8 nm in increasing and decreasing the waveguide width. The results indicate that inaccuracies in the width of the waveguides lead to a resonant shift, but they do not affect the sensor’s sensitivity.

High-frequency signal generators are required in such applications as telecommunications, radar, medical equipment, remote control, probing, radio astronomy, and spectroscopy. One can use an optoelectronic oscillator on a photonic integrated circuit in these applications due to its ease of implementation and low phase noise level. This article considers an optoelectronic oscillator with a phase shifter as a phase modulator implemented in a photonic integrated circuit to simplify the photonic integrated circuit design. The simulation results show that this system can generate microwave signals with a high signal-to-noise ratio (at least 35.27 dB). The side mode suppression ratio was up to 5.94 dB lower than the Mach-Zehnder modulator scheme. This proposed scheme can be used for microwave signal generation in various telecommunication applications and in interrogation tasks.