In this work, we propose and numerically investigate a two‐dimensional microlaser based on the concept of bound states in the continuum (BIC). The device consists of a thin gain layer (Rhodamine 6G dye‐doped silica) sandwiched between two high‐contrast‐grating layers. The structure supports various BIC modes upon a proper choice of topological parameters; in particular it supports a high‐ Q quasi‐BIC mode when partially breaking a bound state in the continuum at Γ point. The optically‐pumped gain medium provides sufficient optical gain to compensate the quasi‐BIC mode losses, enabling lasing with ultra‐low pump threshold (fluence of 17 μJ/cm ² ) and very narrow optical linewidth in the visible range. This innovative device displays distinguished sensing performance for gas detection, and the emission wavelength sensitively shifts to the longer wavelength with the changing of environment refractive index (in order of 5 × 10 ⁻⁴ ). The achieved bulk sensitivity is 221 nm/RIU with a high signal to noise ratio, and a record‐high figure of merit reaches to 4420 RIU ⁻¹ . This ultracompact and low threshold quasi‐BIC laser facilitated by the ultra‐narrow resonance can serve as formidable candidate for on‐chip gas sensor.

Chaos, occurring in a deterministic system, has permeated various fields such as mathematics, physics, and life science. Consequently, the prediction of chaotic time series has received widespread attention and made significant progress. However, many problems, such as high computational complexity and difficulty in hardware implementation, could not be solved by existing schemes. To overcome the problems, we employ the chaotic system of a vertical-cavity surface-emitting laser (VCSEL) mutual coupling network to generate chaotic time series through optical system simulation and experimentation in this paper. Furthermore, a photonic reservoir computing based on VCSEL, along with a feedback loop, is proposed for the short-term prediction of the chaotic time series. The relationship between the prediction difficulty of the reservoir computing (RC) system and the difference in complexity of the chaotic time series has been studied with emphasis. Additionally, the attention coefficient of injection strength and feedback strength, prediction duration, and other factors on system performance are considered in both simulation and experiment. The use of the RC system to predict the chaotic time series generated by actual chaotic systems is significant for expanding the practical application scenarios of the RC.

The coupling between multiple modes in subwavelength scale has attracted a lot of attention due to the interesting physics favored by the enhancement of light-matter interaction. In this contribution, we propose a planar hybrid plasmonic-photonic crystal structure, which enables the tunable coupling between Tamm plasmon-polariton and Fabry-Perot cavity modes. Then, a strong coupling can be achieved through evoking the Tamm-mode dependence of the top-layer thickness of the hybrid structure, which is indicated by an anticrossing with a spectrum splitting of 9.298 meV. The effect enables the spatial confinement of polaritons and the formation of hybrid one-dimensional plasmon-polariton modes. In order to account for the splitting of the orthogonally polarized resonances, a detailed investigation on the TE-TM splitting is also performed through the angular-dependence analysis. We note that the value of the TE-TM splitting strongly depends on the thicknesses of dielectric layer and the distance between two distributed Bragg reflector (DBR) stacks. We show that the cavity modes are extremely sensitive to the distance between the DBR stacks and propose using this feature for strain sensing. Thus, our structure may not only offer a platform for study of interesting physics (e.g., spin optronics), but may also provide a route for high-accuracy strain sensors.

The generation of optical pulses at ultra-low bias level, thus low energy cost, is explored in a commercial microcavity semiconductor laser in view of testing the principle of energy efficient information encoding in potential integrated schemes. Sequences of regular, highly nonlinear pulses with acceptable amplitude stability are obtained from a commercial device as potential sources of bits where the information is added by post-treatment (pulse removal). A discussion on the energy expenditure per bit is offered, together with the optimal frequency for pulse generation, which is found to lie slightly below the above-threshold value declared by the manufacturer.