Propagation of light through localized coupled-cavity modes in one-dimensional photonic band-gap structures

Abstract

Abstract. We report on the observation of a new type of propagation mechanism through evanescent coupled optical cavity modes in one-dimensional photonic crystals. The crystal is fabricated from alternating silicon-oxide/silicon-nitride pairs with silicon-oxide cavity layers. We achieved nearly full transmission throughout the guiding band of the periodic coupled cavities within the photonic band gap. The tightbinding (TB) parameter κ is determined from experimental results, and the dispersion relation, group velocity and photon lifetime corresponding to the coupled-cavity structures are analyzed within the TB approximation. The measurements are in good agreement with transfer-matrix-method simulations and predictions of the TB photon picture. 42.70.Qs; 71.15.Fv; 42.60.Da; 42.82.Et In recent years, the intense theoretical and experimental investigations of photonic band-gap (PBG) [1,2] phenomena have generated a trend towards the use of these materials in certain potential applications. In particular, enhancement of spontaneous emission near the photonic band edges [3], second-harmonic generation [4], nonlinear optical diodes, switches, limiters [5][6][7], a photonic band-edge laser [8] and transparent metallo-dielectric structures [9,10] were reported for one-dimensional (1D) PBG structures. PACS:By introducing a defect into a photonic crystal, it is possible to create highly localized defect modes within the PBG. Photons with certain wavelengths can be trapped locally inside the defect volume [11], which is analogous to the impurity states in a semiconductor [12]. Recently, we demonstrated guiding and bending of electromagnetic (EM) waves along a periodic arrangement of defects inside a threedimensional photonic crystal at microwave frequencies [13,14]. It was also observed that the group velocity tends towards zero and the photon lifetime increases drastically at the coupled-cavity waveguiding band edges [15]. In the coupledcavity structures, photons hop from one evanescent defect mode to the neighboring one due to overlapping between * Author to whom correspondence should be addressed. (E-mail: bayindir@fen.bilkent.edu.tr) the tightly confined modes at each defect site, as illustrated in Fig. 1a [13,16,17]. Due to coupling between the localized cavity modes, a photonic defect band (waveguiding band) is formed within the stop band of the crystal. This is analogous to the transition from atomic-like discrete states to the continuous spectrum in solid-state physics. Recently, Bayer et al. observed formation of a photonic band due to coupling between the optical molecules [18].In this communication, we demonstrate the guiding of light through localized coupled optical cavity modes in 1D PBG structures which are fabricated from siliconoxide/silicon-nitride (SiO 2 /Si 3 N 4 ) pairs with λ/2 SiO 2 cavity layers. It is observed that nearly 100% transmission can be achieved throughout the waveguiding band. The dispersion relation, group velocity and photon lifetime of the coupled cavities are investigated within t...

Strong enhancement of spontaneous emission in amorphous-silicon-nitride photonic crystal based coupled-microcavity structures

“…Recently, we reported a new type of propagation mechanism in which photons move along the localized coupledcavity modes [15,16]. Moreover, it was observed that the group velocity tends to zero and photon lifetime increases drastically at the coupled-cavity band edges [17].…”

Physics and applications of photonic nanocrystals

“…By using 1D PBG structures, potential applications concerning nonlinear optical phenomena were reported such as second harmonic generation [28], pulse compression [29], optical limiting and switching [30,31], filters [32,33], and photonic band edge lasers [34]. Moreover, the modification of spontaneous emission from atoms placed in 1D photonic band gap structures has been demonstrated [35][36][37][38][39]. Similar studies were carried out in two-dimensional photonic crystals involving light emitting diodes [40,41], and photonic crystal based lasers [42,43].…”

“…Since high quality cavities have a crucial role in most of the photonic crystal based applications, investigation of the optical properties of cavities is essential. In recent years, coupled-microcavities have been investigated [45], and used in various applications [38,39,46,47]. These structures consist of two or more planar Fabry-Perot microcavities which are coupled to each other.…”

Photonic-crystal-based beam splitters

“…As an example, we recently demonstrated a new type of propagation mechanism along highly localized cavity modes, i.e., photons can hop from one localized mode to the neighboring cavity modes due to interaction between these modes. [12][13][14][15] This picture can be considered as the classical wave analog of the tight-binding ͑TB͒ approximation in solid state physics. 18,19 The CCWs can be used to construct lossless and reflectionless waveguides and bends in optoelectronic components and circuits.…”