Recent developments in photonic, plasmonic and hybrid nanowire waveguides

Abstract

This review summarizes recent advances in dielectric and plasmonic nanowire waveguides and their hybridization towards better device performance.

Nanowires for Photonics

“…waveguides have been limited to use chemically-synthesized Group 11 transition metals (Au, Ag, and Cu) to minimize propagation losses from surface roughness and crystal quality. 111 Among the metals, since Au and Cu have absorption losses in the visible range due to their d-band transitions,…”

“…From last decades, although Ag nanowire-based plasmonic waveguides have been intensively studied, the measured propagation lengths have been shown significant discrepancies based on their diameter and the measurement conditions. 111,[115][116][117] To elucidate this inconsistency, a chemically-grown Ag nanowire-based SPP modes have been discovered by using a tapered optical fiber tip touching to a suspended Ag nanowire. 115 For optical elements integration, a structure-dependent SPPs loss such as bending loss has to be also considered.…”

Toroidal Metaphotonics and Metadevices

“…The geometric values and cross-sectional schematic of the proposed design are indicated in Figure 7b,c, respectively. Here, the ITO sublayer (100 nm) is considered as the nonlinear material with superior third-order coefficient ( (3) ), while the unit cells serve field enhancement to amplify the thirdorder harmonic signal. Figure 7d represents the SEM image of the fabricated 2D metastructure.…”

“…Futuristic and strategic technology requirements will push the limits of light toward subwavelength photonic integration and energy efficiency, beyond that of bulk optical components, silicon photonics, and plasmonic nanocircuits. [1][2][3][4][5] This integration can be attained by considering the data processing and waveguiding characteristics at more basic level, and the only possible way of overcoming those challenges is employing the concepts of metamaterials and metadevices based on structuring artificial matter at the subwavelength scales. [6][7][8] Optical magnetism, [9][10][11] asymmetric transmission, [12][13][14] hyperbolic dispersion, [15][16][17][18] epsilon near-zero (ENZ), [19][20][21][22] topological states, [23][24][25][26][27] arbitrary control of light's trajectories and cloaking, [28,29] excitation of toroidal fields and charge-current configurations, [30][31][32][33] and generation of flying doughnuts [34,35] are some of the fundamental discoveries that are allowed by metamaterials.…”

“…, where 0 is the vacuum permittivity, c is the speed of light, is the wavelength of the fundamental harmonic, n and n 3 are the refractive indices at the fundamental ( = 785 nm) and third ( THG = 262 nm) harmonic frequencies, w 0 is the beam waist radius, l is the interaction length, and P and P 3 are the peak powers at the fundamental and third harmonic, respectively. The calculated(3) eff of the toroidal metasurface, nanodimer system, and an unpatterned ITO film revealed that(3) eff (toroid) (1.2 × 10 -21 m 2 .V −2 ) is 2.2 and 3.1 times larger than that of the nanodimer and the unpatterned sublayer, respectively. Ultimately,Figure 7lsummarizes the effect of the ITO thickness on the generated nonlinear signal intensity.…”