Miniature, All-Silica, Fiber Optics Sensors Produced by Selective Etching of Phosphorus Doped Silica Glass ^†

All-silica optical fiber structures created at the tip, within or along optical fibers can provide unique opportunities for a design of temperature insensitive, robust and fully dielectric micro-optical sensors as shown on Figure 1. This contribution will discuss design, manufacturing and typical performance of micro-fiber sensors created by mask-less micromachining process, which is based on a selective etching of optical fibers [1]. The proposed micromachining is accomplished through introduction of proper dopants in into designated areas of specialty structure-forming fibers. Short sections of these structure-forming optical fibers are spliced to standard or other fibers and etched into different micro-sensor devices. The prosed approach is especially useful for creation of miniature-all silica Fabry-Perot sensors [2,3], miniature micro/nanowire sensor structures, absorption microcells, and similar sensors. Furthermore, the present process allows for formation of micro-sensor structures suitable for sensing of multiple parameters. The proposed micromachining process also provides a versatile and potentially cost-efficient method of all-fiber sensor manufacturing through the design and production of specialty SFFs.

Figure 1. Micromachined sensor devices: (a) Pressure sensor (side polished to expose diaphragm), (b) Micro-resonator (c) Microcell on the fiber tip, (d) Strain sensor, (e) Relative humidity sensor, (f) Refractive index and pressure sensor, and (g) Four parameter sensor for sensing of: thermal conductivity, pressure, refractive index and temperature.

Figure 1. Micromachined sensor devices: (a) Pressure sensor (side polished to expose diaphragm), (b) Micro-resonator (c) Microcell on the fiber tip, (d) Strain sensor, (e) Relative humidity sensor, (f) Refractive index and pressure sensor, and (g) Four parameter sensor for sensing of: thermal conductivity, pressure, refractive index and temperature.