Thermal fluctuation analysis of singly optically trapped spheres in hollow photonic crystal cavities

Abstract

We report on the behaviour of singly optically trapped nanospheres inside a hollow, resonant photonic crystal cavity and measure experimentally the trapping constant using back-focal plane interferometry. We observe two trapping regimes arising from the back-action effect on the motion of the nanosphere in the optical cavity. The specific force profiles from these trapping regimes is measured.

Single nanoparticle trapping based on on-chip nanoslotted nanobeam cavities

“…Moreover, a trapping potential depth in this work as large as 1.15 × 10 5 k B T mW −1 is obtained. Threshold power of only 0.087 μW is required for stable trapping, which is significantly decreased compared to previous PC cavity designs [39][40][41]53].…”

“…So far, via optical trapping, a large number of different nanoparticles including dielectric/metallic nanoparticles, single cells, and even single atoms can be manipulated [8][9][10]. Particularly, to further establish trapping nanoparticles with lower input powers, a number of new, near-field optical manipulation techniques, such as optical nanofibers [11][12][13], photonic crystal (PC) fibers [14,15], whispering gallery mode carousels [16][17][18][19][20], plasmonic tweezers [21][22][23][24], solid waveguides [25,26], slot waveguides [27,28], microring resonators [29], photonic crystal waveguides [30][31][32], and photonic crystal cavities [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50], have been developed to exploit the strong spatial field gradient forces and to increase the field amplitude inside the devices. Among these, photonic crystal cavities have been investigated as advantageous platforms for cavity-enhanced optical trapping and sensing due to their a...…”

“…Among these, photonic crystal cavities have been investigated as advantageous platforms for cavity-enhanced optical trapping and sensing due to their advantage in high Q∕V , where Q is the quality factor and V is the cavity mode volume. Particularly, compared with two-dimensional (2D) PC cavities [33][34][35][36][37][38][39], one-dimensional (1D) PC nanobeam cavities [40][41][42][43][44][45][46][47][48][49][50] have attracted great attention for integrated on-chip trapping and manipulation due to their attractive properties of ultracompact footprints and convenient integration with bus-waveguides. Examples of such systems include a 1D PC cavity with waist design for efficient trapping and nanoparticle detection presented by Lin et al, where an optical trapping force of 2.3 pN/mW for a 100 nm diameter polystyrene (PS) nanoparticle was observed [40]; Serey et al theoretically showed that nanoparticles as small as 7.7 nm in diameter can be trapped with a trapping potential depth of 500 k B T when the input power is 10 mW, where k B is the Boltzmann constant and T is the system temperature [41]; Mandal et al presented a class of silicon 1D PC resonant optical trapping for nanomanipulation and observed that the maximum trapping force of 700 pN/W for a 100 nm diameter PS nanoparticle was achieved [42]; Han and Shi theoretically showed that an optical trapping force as high as 300 pN/mW for a 200 nm diameter PS nanoparticle in a 1D PC system was achieved [49].…”

Nanophotonic trapping: precise manipulation and measurement of biomolecular arrays

“…Interestingly, by analyzing the intensity of light scattered by a trapped particle, they quantified the interaction force between the resonator surface and a 100 nm trapped particle with sub‐pN resolution—a technique they named nanophotonic force microscopy (NFM) . Two‐dimensional photonic crystal optical traps have also been reported for precisely measuring the size distribution of sub‐100 nm gold nanoparticles, and trapping and analyzing larger dielectric particles ( d > 0.25 µm) and bacteria at sub‐mW powers . These latter devices hold potential for applications in bacteria sensing or analysis.…”

“…66 Two-dimensional photonic crystal optical traps have also been reported for precisely measuring the size distribution of sub-100 nm gold nanoparticles, 67 and trapping and analyzing larger dielectric particles (d > 0.25 μm) and bacteria at sub-mW powers. [68][69][70][71][72][73] These latter devices hold potential for applications in bacteria sensing or analysis. Additionally, Renaut et al demonstrated rotational orientation control for a pair of adjacent 1 μm microspheres trapped on a photonic crystal, 74 indicating short-range nanomanipulation may also be achieved with photonic crystal optical traps.…”