Multiple-wavelength-transmission filters based on Si-SiO2 one-dimensional photonic crystals

Abstract

The Si/SiO2 one-dimensional photonic crystals of heterostructural multilayers with two periods, ΛA and ΛB, have great potential for multiple-wavelength-transmission filters. These structures were prepared by inserting N pairs of ΛB (as the defect region) in the middle of two sets of two pairs of ΛA, so that the structure becomes air→[(2∙ΛA)→(N∙ΛB)→(2∙ΛA)]→substrate. N means the number of ΛB pairs in the defect region. The complex refractive indices of Si and SiO2 are assumed to be 3.7+i0 and 1.5+i0 in the transfer matrix calculation. The number of transmission channels or defect branches m is given by 2N, that is, m=2N. For large N(>10), the photonic band gap exists in a normalized frequency range ω of 0.0846–0.3838, which corresponds to the wavelength range of 0.84–6.67 μm. The defect branches are placed on a branch band between two symmetric flat bands. For a filling factor η=0.406, a matching condition of optical length in two alternating layers, the branches at the center of the branch band are divided into a uniform frequency interval. In particular, we claim that the transmission-defect branches can be precisely tuned by controlling the incident angles without external applied bias.

Photonic Crystal Ring Resonator Based Optical Filters

“…The defect mode is then localized in one direction however it is extended into other two directions. An example for such a 1DPC is the well known dielectric Bragg mirror consisting of alternating layers with low and high refractive indices, as shown in Figure 2 The wavelength selection and reflection properties in 1DPCs are used in a wide range of applications including high efficiency mirrors [12,13], optical filters [14,15,16], waveguides [17], and lasers [18]. Also, such structures are widely used as anti-reflecting coatings which dramatically decrease the reflectance from the surface and used to improve the quality of the lenses, prisms and other optical components.…”

Combined wet and dry cleaning of SiGe(001)

“…In order to overcome challenges when scaling down silicon-based complementary metal-oxide semiconductor devices, SiGe has received much attention due to its high carrier mobility and application in strain engineering. [1][2][3] SiGe has a higher hole mobility, which makes it useful as a replacement for Si as a channel material in P-type metal-oxide-semiconductor (PMOS) transistors. [4][5][6] Additionally, the larger lattice constant of SiGe can be utilized to improve electron mobility in N-type metal-oxide-semiconductor transistors by inducing a biaxial tensile strain into Si channels.…”

“…(Color online) STM images of wet and dry cleaned SiGe(001). (a) Filled state STM image (50 Â 50 nm2 , V s ¼ À1.8 V, I t ¼ 200 pA) after 330 C anneal. (b) STM image (50 Â 50 nm 2 , V s ¼ À1.8 V, I t ¼ 200pA) after 550 C anneal.…”

SOI Ridge Waveguide Incorporating a Photonic Crystal Microcavity Multi-Channel Filter

“…Transmission peaks occurred at 1168, 1321 and 1562 nm wavelengths, meeting the design specification. OCIS codes: 230.3990, 230.4000, 250.3500, 310.2790 Microcavity filters based on photonic crystal PhC) structures have received considerable attention recently [1][2][3]. In principle, one-dimensional 1-D) PhC structures can be readily incorporated into ridge waveguides conventionally used in photonic integrated circuits to increase component densities.…”

“…1 shows schematically device structure, which comprises, from left to right, a two period reflector of period Λ A , a cavity section formed by another 1D PhC of period Λ B ≠Λ A ) followed by a second two period reflector period Λ A ). The period, refractive index contrast and air fraction of the inner 1D PhC are tuned until its pass band lies within the first band gap of the 1D PhCs of period Λ A used to form the reflectors [2]. Consequently, the transmission wavelengths are adjustable with several degrees of freedom, for which a rapid design optimisation procedure is ideally required.…”