High transmission recovery of slow light in a photonic crystal waveguide using a hetero groupvelocity waveguide

Abstract

High transmission of slow-light in a photonic crystal (PC) waveguide (WG) using a hetero group-velocity (Ht-V(g)) PC-WG was proposed and experimentally investigated. The Ht-V(g) WG, which comprises a low-group-velocity (L-V(g)) PC-WG section between two identical high-group- velocity (H-V(g)) PC-WGs, is designed to decrease the impedance mismatch of the L-V(g) PC-WG. The increase in transmittance of a propagating pulse was confirmed in the Ht-V(g) PC-WG even in the vicinity of the band-gap, whereas the homogeneous PC-WG showed a gradual decrease in transmittance with the pulse wavelength approaching the band-gap. The group index (n(g)) of the L-V(g) region in the Ht-V(g) PC-WG was measured by the cross-correlation method and attained a value above 20. On the other hand, the transmittance of the Ht-V(g) structure recovered approximately 16dB compared to the homogeneous L-V(g) WG having same n(g), 17. This recovery is mainly dominated by the coupling improvement due to the Ht-V(g) structure, around 12dB. These results indicate the effectiveness of the Ht-V(g) structure to use slow light in a PC-WG, which leads to various applications in PC-based optical devices.

Light transport regimes in slow light photonic crystal waveguides

“…[37][38][39] A striking features in the evolution of the dispersive part of the field is its steep extinction. This contrast with the progressive linewidth broadening at the band edge expected when the disordered potential and the physical origin of the band edge are uncorrelated.…”

Low velocity propagation in liquid in-filled photonic crystal waveguides

“…Hence the intensity reduction at this interface is not significant. The coupler-based approach described in reference [27] and [42] can be used for efficient coupling into the slow light regimes. …”

“…One way of overcoming this problem of impedance mismatch is the use of adiabatic tapers [26] but these tend to be long and lack systematic design procedure. Other way is to introduce a finite region which couples the light from ridge, first into fast mode PhC waveguide and then into slow mode PhC waveguide [27][28][29][30]. Such issues of concern are tackled directly in the proposed paper, in order to obtain a highly efficient slow light PhC waveguide with a simple design for easy fabrication.…”

Optical-Nonlinearity-Induced Phase Shift via Selective-Area Grown InAs Quantum Dots in a Photonic Crystal Waveguide

“…Here, the slow light with the group velocity of 0:05c (c is the light velocity in vacuum) is assumed. 12) The size of less than 500 mm seems to be sufficiently small for a novel optical integrated circuit, and the energy of less than 100 fJ is also likely to be sufficiently low for an ultrafast all-optical switch.…”