Photonic crystal device

Rajic, S., Corbeil, J. L. Datskos, P. G. Feasibility of tunable MEMS photonic crystal devices. Ultramicroscopy 97, 473-9 (2003). 

Photolithography is a high quality, high cost method to fabricate two- and three-dimensional photonic crystal materials for photonic applications. This top-down fabrication concept produces complex photonic crystal materials but the high cost is likely to prevent commercialization of many photonic crystal devices. 

As shown in Fig. 8.9A, a full-color photonic crystal device was designed and fabricated in a form of electrochemical cell (Arsenault et al., 2007). The device was based on a two-component composite, that is, silica microspheres and polyferrocenylsilane (PFS). The silica microspheres with an ordered self-assembly array were deposited on ITO glass substrate and served as the inactive structural scaffold. PFS with pendant unsaturated C=C bonds were incorporated into the lattice spacing of silica microspheres and polymerized... 

These biosensors utilize the optical properties of lasers to monitor and quantify the interactions of biomolecules that occur on functionalized surfaces or in solutions. They are further subdivided into evanescent field-based devices [5], photonic crystal devices [6], and surface plasmon resonance devices [7]. 

As mentioned earlier, colloidal photonic crystal devices were fabricated through a self-assembly process. This process is the most economic method to produce 3D nanostructures. When the size of a colloidal building block is half the wavelength of visible light, a physical change of the photonic crystals caused by the analytes converts into a color change. However, the width of the reflectance peak is usually broad, which disturbs the high sensitive characterization. 

Li, J., P.J. Neyman, M. Vercellino, J. R. Heflin, R. Duncan, and S. Evoy. 2004. Active photonic crystal devices in self-assembled electro-optic polymeric materials. Mater Res Soc Symp Proc 817 133-138. 

In addition, it is very important to arrange, align, orientate, and integrate these polymer and/or hybridized NCs exactly and selectively on a substrate [55-59, 61, 87], and one should keep such kinds of NCs in mind in order to input and output optical- and electric-signals and/or information for device application. Here, encapsulation of polymer NCs and their arrangement by the use of a lithographically patterned substrate have been proposed to solve the above-mentioned problems [61]. As a typical example, the assembled structure of polymer microspheres (MSs) having mono-dispersed size is well known in the applications of some photonic crystal devices [87], In contrast, the proposed fabrication procedures seem to be much more extensive and superior to the previous ones. 

Fig. 16.2 Nanoscale optofluidic sensor arrays (NOSA). (a) 3D illustration of a NOSA sensing element. It consists of a ID photonic crystal microcavity, which is evanescently coupled to a Si waveguide, (b) The electric field profile for the fundamental TE mode propagating through an air clad Si waveguide on SiOi. (c) SEM of a NOSA device array. It illustrates how this architecture is capable of two dimensional multiplexing, thus affording a large degree of parallelism, (d) Actual NOSA chip with an aligned PDMS fluidic layer on top. Reprinted from Ref. 37 with permission. 2008 Optical Society of America...

Three-dimensional (3D) structuring of materials allows miniaturization of photonic devices, micro-(nano-)electromechanical systems (MEMS and NEMS), micro-total analysis systems (yu,-TAS), and other systems functioning on the micro- and nanoscale. Miniature photonic structures enable practical implementation of near-held manipulation, plasmonics, and photonic band-gap (PEG) materials, also known as photonic crystals (PhC) [1,2]. In micromechanics, fast response times are possible due to the small dimensions of moving parts. Femtoliter-level sensitivity of /x-TAS devices has been achieved due to minute volumes and cross-sections of channels and reaction chambers, in combination with high resolution and sensitivity of optical con-focal microscopy. Progress in all these areas relies on the 3D structuring of bulk and thin-fllm dielectrics, metals, and organic photosensitive materials. 

Matsuo S, Kondo T, Juodkazis S, Mizeikis V, Misawa H (2002) Fabrication of three-dimensional photonic crystals by femtosecond laser interference. In Adibi A, Scherer A, Lin S-Y (eds) Photonic bandgap materials and devices. SPIE Proc 4655 327-334... 

Losses still occur in the fibres developed for commercial use. Nonetheless, these have been reduced to a point where transmission over kilometres is possible. Along with transmission of information in telephone systems and similar applications, it has been suggested that optical devices may replace conventional electronics in more advanced applications such as computers. For such applications, it will be necessary to develop optical switches, amplifiers, and so on. In the last two decades, new materials have been developed that may form the basis of integrated optical circuits. These materials are photonic crystals. 

Particularly in 2D systems, control over the self-assembly of colloidal templates has offered a versatile way to produce patterned surfaces or arrays with a precision of few nanometres. Diblock copolymer micellar nanolithography (dBCML) is a versatile method that uses homopolymers or block copolymers for the production of complex surface structures with nanosized features [69], In contrast to other approaches like electron-beam lithography (EBL) and photolithography, dBCML does not require extensive equipment. In fact, it is commonly used in the fabrication of data storage devices and photonic crystals, in catalyses [70], and for the design of mesoporous films and nanoparticle arrays [71]. 

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