Waveguides, planar fabrication processes

They are technologically easier to construct than conventional planar waveguides and the fabrication processes are more economic and rugged. Conventional waveguides need thicker substrates (10 times thicker) than ARROW structures to reach equivalent losses in this layer. Moreover, they are less suitable to develop optical sensors based on the core propagation, because if the membrane refractive index was the same, a thickness of about 100 nm would be needed to achieve single-mode behavior in the transversal direction to the layers. ARROWS have a 4-pm-thick core,... 

R. de Melo Jr, B. da Silva, E.L. Falcao-Filho, E.F. da Silva Jr, D.V. Pretrov, Cid B. de Araujo, Y. Messaddeq, M. A. Aegerter, Novel Fabrication process of planar optical waveguides in rare-... 

A disposable, patterned, planar waveguide with a number of individual wells has been reported for a one-step homogeneous immunoassay of IgG.<133) The device is fabricated by an ion-exchange process, etching, and covalent reagent immobilization. The sample fills the waveguide by capillary action. The sample well, as well as fluorescent and nonfluorescent control wells are excited by an evanescent field, and individually scanned. The IgG detection limit is in the 10range. 

Fig. 6 Types of planar waveguides depending on the processes employed for their fabrication...

On the other hand, deposition-based waveguides usually have a squarelike geometry in a strip, a strip-loaded or a rib configuration (Fig. 6). They are fabricated by depositing several layers onto a planar substrate by means of microelectronic processes, covering and etching them until the final geometry is obtained. 

A photoresist pattern was deposited on a nonlinear diazo dye film and then oxygen etched to form a line of nonlinear and linear sections with a 32 pm QPM period. The upper surface was then planarized with a UV cured resin. A raised QPM +/0 channel waveguide was then formed with three more processing steps [104]. Despite the complexity of the fabrication, losses were below 3 dB cm 1 at 1.59 pm and a maximum SHG figure of merit of 4x10 % W 1 cm 2 was obtained [105,106]. 

Device Fabrication The relative ease of control of the sol-gel process renders it suitable for device fabrication such as thin films, optical fibers, and optical waveguides (both channel and planar). 

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