Highly Efficient Coupling of Nanolight Emitters to a Ultra-Wide Tunable Nanofibre Cavity

Abstract

Solid-state microcavities combining ultra-small mode volume, wide-range resonance frequency tuning, as well as lossless coupling to a single mode fibre are integral tools for nanophotonics and quantum networks. We developed an integrated system providing all of these three indispensable properties. It consists of a nanofibre Bragg cavity (NFBC) with the mode volume of under 1 μm3 and repeatable tuning capability over more than 20 nm at visible wavelengths. In order to demonstrate quantum light-matter interaction, we establish coupling of quantum dots to our tunable NFBC and achieve an emission enhancement by a factor of 2.7.

Optical nanofiber-based cavity induced by periodic air-nanohole arrays

“…To reduce complexity and to compensate for the general unsatisfactory scalability of light-matter systems in free space, optical nanofibers (ONFs) are proving to be a very useful tool for hybrid quantum devices wherein quantum emitters are coupled to the fiber-guided modes via the evanescent field extending from the nanofiber surface. In recent years, significant research effort has been invested in order to interface various quantum emitters, including neutral atoms, 1-7 semiconductor quantum dots, 8,9 and nitrogenvacancy centers in diamond, 10 to the light fields of ONFs. With tight, transverse-mode confinement and the relatively high intensity of the evanescent field, efficient light-matter coupling 11 and low optical power nonlinearities [12][13][14] have been experimentally demonstrated.…”

“…26 A composite photonic crystal cavity based on a nanofiber has also been formed by means of an external grating 27 and has been used to observe a significant enhancement of the spontaneous emission rate of single quantum dots into nanofiber guided modes. 8,9,28 In addition, a fiber ring cavity containing a nanofiber section that strongly couples atoms to the cavity mode has been studied recently. 29,30 In this letter, we investigate a nanofiber-based cavity that incorporates both FBG and PhC structures in order to exploit the advantages of both simultaneously.…”

Fabrication and characterization of optical nanofiber interferometer and resonator for the visible range

“…The nanofiber cavity with fiber beam splitter gives a big mode volume according to the cavity length of more than two meters [20]. The nanofiber Bragg cavity has the smallest mode volume among the achieved methods for nanofiber based cavity [14], the mode volume is 1 μm 3 , which is achieved with a fabrication process far more demanding than ours.…”

“…Using a Talbot interferometer, it has been possible to fabricate two fiber Bragg gratings and form an optical cavity with a transmission of 87% for a finesse of 39 [12]. A similar strategy, called nanofiber Bragg cavity, where a focused ion beam mills the nanofiber to create mirrors has shown a Purcell factor and coupling efficiency of 19.1% and 82% respectively [13,14]. Another solution relies on coupling the nanofiber with a whispering gallery mode resonator with very high quality factor up to 10 9 [15,16].…”

Imaging light scattered by a subwavelength nanofiber, from near field to far field

“…They have been attracting much interest since the 2000s, for biosensors [3], quantum information [4,5], coupling light to bigger structures (microspheres [6], photonic crystals [7], microdisks [8],...) to quantum emitters (cold atoms [9,10], CdSe quantum dots [11], nitrogen vacancy in diamond [12], hBN flakes [13], single molecules [14], ...). Nanofibers can also be processed [15][16][17], for instance into nanofiber cavities to enhance the coupling efficiency of an emitter on the surface into its fundamental mode [18]. More than just light wires, nanofibers confine the transverse electromagnetic field to the point that a longitudinal component appears [19], bonding the local polarization of light to its propagation direction; also known as spin-orbit coupling of light [20] or spin-momentum locking [21], this effect opens new possibilites in photonics [22,23].…”