Optical fiber alignment

This chapter provides an overview of the basic principles and designs of such sensors. A chemical sensor to detect trace explosives and a broadband fiber optic electric-field sensor are presented as practical examples. The polymers used for the trace explosive sensor are unpoled and have chromophores randomly orientated in the polymer hosts. The electric field sensor uses a poled polymer with chromophores preferentially aligned through electrical poling, and the microring resonator is directly coupled to the core of optical fiber. 

In the present experiment, the optical fiber is aligned to the sensor chip using a separate micropositioner, and no antireflection coatings are used on the chip facets. As a result, the observed noise floor is limited by vibrations and interference effects of the present experimental setup. With the adoption of well-established packaging... 

Fig. 19 The sensor can be separated into three main parts. 1 A V-grooved auxiliary support, where the optical fibers are fixed, 2 the exchangeable transducer based on curved ARROW waveguides, where the membrane is deposited and 3 a connection platform, which allows the alignment of the transducer waveguides to the optical fibers, which are fixed in the auxiliary support by the aid of two microfabricated channels at both sides of the surface...

The optical fibers were loaded in an array of up to 40 fibers each placed in an individual U-shaped groove cut into an aluminum block, shown in Fig. 4.13. This technique allowed multiple fibers to be imprinted with the cicada wing mould in a simple and rapid manner that was not critically reliant upon alignment. The resolution obtained with this method was better than 15 nm, producing bidirectional optical fiber prober for SERS with enhancement factors only slightly less than those obtained from the original structures on the cicada wings. 

Fig. 4.12 A process schematic diagram of the rapid, self-aligned array-imprinting sequence used by Kostovski et al. to reproduce nanostructures on optical fibers using a nonplanar mould (Reproduced with permission from [47])...

Kostovski G, Chinnasamy U, JayawardhanaS et al (2011) Sub-15 nm optical fiber nanoimprint lithography a parallel, self-aligned and portable approach. Adv Mater 23(4) 531-535... 

Optical output power = / laser facet power, laser placement, lens placement, fiber alignment... ... 

Laser Facet Power (mW) Laser Placement (Aim) Lens Placement (nuls) Fiber Alignment (dB) Optical Output Power (mW)... 

In the example, a design model was first developed that indicated that optical output power is a function of laser facet power, laser placement, lens placement, and fiber alignment. To control optical output power, statistical process control must be applied to these critical process output parameters and, where apphcable, must be applied to corresponding process input parameters. 

For optimum performance as strain and temperature sensors, embedded optical fibers should be mounted between two collincar plies and be aligned with the reinforcing fibers. Maximum sensitivity is achieved when fibers arc embedded as close to the surface of maximum tensile strain as possible, and sandwiched orthogonally between a pair ol ct>l-... 

Precision alignment and attachment of optical fibers to couple them with lenses, transmitter and receiver components, and laser diodes is stiU largely a manual, labor-intensive process. Optical fibers must be aligned to insure that the optimum amoimt of light is transmitted between the fiber on the outside and the laser, photodiode, or other optical component on the inside of a package. Alignment may be active or passive. ... 

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