Photonic stop gap

Whilst not showing full band gap capability self-assembled photonic oystals do show interesting incomplete bands, known as stop gaps. For instance, 3D crystalline arrays from differently sized PS beads show different colours in transmission 270 nm beads give a red colour (absorbance at /L = 650 nm), 220 nm beads a green colour (absorbance at A = 550 nm) and 206 nm beads a blue colour (absorbance at 7=460 nm). 

Over the last several decades photonic band-gap materials attracted considerable interest due to the possibility of inhibition of the spontaneous emission and light propagation [1-3]. Mesoporous structures like three-dimensional artificial opals and two-dimensional PAA are considered as photonic band gap materials, demonstrating the photonic stop-band in transmission and reflection spectra [4,5] and anisotropy of photonic density of states (DOS) on scattering indicatrices [6]. An influence of photonic band-gap materials on photoluminescence and spontaneous emission rate of the embedded inclusions have been reported and discussed [7-9]. 

Seet, K.K., Mizeikis, V, Juodkazis, S., and Misawa, H. (2006) Three-dimensional horizontal circular spiral photonic crystals with stop gaps below 1 mu m. Appl. Phys. Lett., 88 (22), 221101. 

Reflectivity is greatly increased in a dielectric stack with a larger number of layers. A typical spectral dependence of a dielectric mirror is shown in Fig. 2.37. The wavelength range of maximum reflectivity is called the stop band (sometimes also called one-dimensional photonic band gap). Increasing the ratio between the low and high-refractive index parts extends the width of the stop band. 

Seet, K.K., Mizeikis,V.,Juodkazis, S., Misawa, H., 2006.Three-dimensional horizontal circular spirals photonic crystals with stop gaps below 1 pm. Appl. Phys. Lett. 88 (22), 221101. Seet, K.K., Juodkazis, S., Jarutis,V., Misawa, H., 2006. Feature-size reduction of photopoly-merized structures by femtosecond optical curing of SU-8. Appl. Phys. Lett. 89,24106. Seet, K.K., Mizeikis, V., Matsuo, S., Juodkazis, S., Misawa, H., 2005. Three-dimensional spiral - architecture photonic crystals obtained by direct laser writing. Adv. Mat. 17 (5), 541-545. 

Aliev et al. (2010) used acoustic transmission spectroscopy to measure directly the bandgap of an ADBR showing a first-order bandgap at 0.65 GHz with a stop band depth of at least 50 dB and a weaker second-order gap at 1.3 GHz. The sample was also characterized using both its photonic and phononic stop band properties, i.e., consistently using Eqs. 1 and 2, which demonstrates the phoxonic nature (Sadat-Saleh et al. 2009) of porous silicon superlattices. 

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