A Monolithic Graphene‐Functionalized Microlaser for Multispecies Gas Detection

Abstract

of biological and chemical sensing, where they provide ultrahigh frequency resolution in sub-MHz level [10] by measuring the passive interference between different cavity modes [11] as well as the shift and/ or broadening of the mode resonances. [12] With such approach, detection of individual cells, [13,14] viruses, [15] protein molecules, [16] DNA, [17,18] and nanoparticles [19,20] has already been achieved. Further enhancement of the performances of a WGM-based sensor can be obtained in an active cavity, where the monolithic integration of a laser provides higher stability and improved frequency resolution. [21,22] Such platforms hold great promise also for applications in the field of gas sensing, however, the materials used in conventional WGM microcavities (silica or metal fluorides) are inert and thus unsuitable for gas adsorption and tracing. On the other hand, the hybridization of 2D materials with microcavities, such as chip microrings, [23][24][25] plasmonic resonators, [26,27] nanowires, [28] fiber microcavities, [29,30] and WGM microresonators, [31][32][33] offers a new route for enhanced photon-electron interactions and thus provides a novel platform for gas detection. [34] Here we realize an active WGM microsphere laser device functionalized with single-layer graphene that is capable of Optical-microcavity-enhanced light-matter interaction offers a powerful tool to develop fast and precise sensing techniques, spurring applications in the detection of biochemical targets ranging from cells, nanoparticles, and large molecules. However, the intrinsic inertness of such pristine microresonators limits their spread in new fields such as gas detection. Here, a functionalized microlaser sensor is realized by depositing graphene in an erbium-doped over-modal microsphere. By using a 980 nm pump, multiple laser lines excited in different mode families of the microresonator are co-generated in a single device. The interference between these splitting mode lasers produce beat notes in the electrical domain (0.2-1.1 MHz) with sub-kHz accuracy, thanks to the graphene-induced intracavity backward scattering. This allows for lab-free multispecies gas identification from a mixture, and ultrasensitive gas detection down to individual molecule.

Nonlinear Dispersion Relation and Out‐of‐Plane Second Harmonic Generation in MoSSe and WSSe Janus Monolayers

“…First, a high degree of compatibility with on-chip photonic architectures. [46][47][48][49] Second, their atomically thin nature combined with a strong nonlinear response [1,50] allows for efficient frequency conversion without phase matching constraints, [51,52] and thus, provides a viable route towards ultra-broadband classical and quantum sources of light. Janus TMD monolayers further expand such advantages by respectively adding out-of-plane components in the nonlinear optical response, [53][54][55] which introduce an additional functionality to be harnessed in vertical photonics structures, [56,57] and widening the spectral region of resonantly enhanced nonlinear optics to different areas of the visible and near-infrared light.…”

Co‐Generation of Orthogonal Soliton Pair in a Monolithic Fiber Resonator with Mechanical Tunability

“…For achieving higher resolution, the shift of Δf ceo is further down-mixed with a microwave generator (MWG) and tested by using the lock-in amplification scheme. [39,40] Such a number is considerably large for an ultrasensitive force meter. Figure 4c plots the linear response of our comb sensor for force detection.…”

Whispering-Gallery Mode Optoplasmonic Microcavities: From Advanced Single-Molecule Sensors and Microlasers to Applications in Synthetic Biology

“…Microlasers are one of the most powerful label-free sensing platforms for single nanoparticles, viruses, and even multispecies and individual gas molecule detection. , WGM microlaser properties and fabrication methods have been extensively studied. Among many methods of fabrication, from quantum dots (QDs) to organic dyes and from microbubbles to microtoroids, the most robust and cost-effective fabrication method is doping silica microspheres with rare earth ions. , The simple level structure and higher gain efficiency of Yb 3+ , which enables laser operation at low-quality factors, make this ion a favorable dopant for sensing applications.…”