Multispecies and individual gas molecule detection using Stokes solitons in a graphene over-modal microresonator

Abstract

Soliton frequency combs generate equally-distant frequencies, offering a powerful tool for fast and accurate measurements over broad spectral ranges. The generation of solitons in microresonators can further improve the compactness of comb sources. However the geometry and the material’s inertness of pristine microresonators limit their potential in applications such as gas molecule detection. Here, we realize a two-dimensional-material functionalized microcomb sensor by asymmetrically depositing graphene in an over-modal microsphere. By using one single pump, spectrally trapped Stokes solitons belonging to distinct transverse mode families are co-generated in one single device. Such Stokes solitons with locked repetition rate but different offsets produce ultrasensitive beat notes in the electrical domain, offering unique advantages for selective and individual gas molecule detection. Moreover, the stable nature of the solitons enables us to trace the frequency shift of the dual-soliton beat-note with uncertainty <0.2 Hz and to achieve real-time individual gas molecule detection in vacuum, via an optoelectronic heterodyne detection scheme. This combination of atomically thin materials and microcombs shows the potential for compact photonic sensing with high performances and offers insights toward the design of versatile functionalized microcavity photonic devices.

Soliton microcombs in whispering gallery mode crystalline resonators with broadband intermode interactions

“…In addition, the Raman lasing was observed in company to the soliton comb in our crystalline resonators, which in contrast to previous understandings could be in a low-noise and stabilized state. A suspect Raman-soliton comb was also observed around the anti-stokes side, rather than being on the stokes side as previously reported in high-Q silica microresonators [55,56].…”

“…Effects of broadband intermode interactions are experimentally evidenced, which would not only tailor the soliton comb spectrum, but also enhance the soliton power efficiency. We also demonstrate soliton combs in company with the Raman lasing, including both narrow-band lasers and Raman-Kerr combs [51][52][53][54], and a suspect Raman-soliton comb [55,56] around the anti-stokes mode. The transmission of the resonance that is pumped and scanned by an intense cw laser, in which the stair-like pattern (soliton steps) indicates the formation of dissipative solitons in the cavity.…”

Fabrication Technologies for the On‐Chip Integration of 2D Materials

“…[126] The patterning of ultrathin graphene, [195] GO, [207] TMDCs, [217,224] and perovskite [258] films has formed the basis of flat optical lenses. Chip-scale sensors incorporating 2D materials have also demonstrated the detection for a wide range of targets, from gases, [30,239,285] humidity, [235,281] and metal ions, [31,218] to pressure, [32,270] and biomolecules. [31,271,286]…”

Dual-mode microresonators as straightforward access to octave-spanning dissipative Kerr solitons

“…Dissipative Kerr soliton (DKS), as a self-reinforcing wave packet that maintains its shape while circulating around a microresonator, has been demonstrated under a double balance between nonlinearity and dispersion, as well as parametric gain and cavity loss [1,2]. Due to the unprecedented compactness, low-noise, high power-efficiency, and broad spectral bandwidth, soliton Kerr combs (microcombs) have attracted considerable research interest and been extensively studied for spectroscopy [3], communications [4], frequency synthesizer [5], optical clock [6], microwave photonics [7] and sensor applications [8]. Over the past several years, through the substantial exploration of the fundamental physics and microresonator fabrication, researchers have realized Kerr solitons in a growing number of platforms, including ultra-high Q MgF 2 [9], silica [10], and monolithic integrated platforms such as Si 3 N 4 [1,[11][12][13], LiNbO 3 [14], AlGaAs [15] and Ta 2 O 5 [16], as well as the wide-bandgap semiconductors AlN [17,18], SiC [19] and GaN [20].…”