A Review of Multimode Interference in Tapered Optical Fibers and Related Applications <s> TOF Structures and Their Fabrication <s> A model for the shape of optical fiber tapers, formed by stretching a fiber in a heat source of varying length, is presented. Simple assumptions avoid any need for the techniques of fluid mechanics. It is found that any decreasing shape of taper can be produced. The procedure for calculating the hot-zone length variation required to produce a given shape of taper is described, and is used to indicate how an optical adiabatic taper can be made. A traveling burner tapering system is capable of realizing the model's prediction, and a complete practical procedure for the formation of fiber tapers with any reasonable shape is thus presented. > <s> BIB001 </s> A Review of Multimode Interference in Tapered Optical Fibers and Related Applications <s> TOF Structures and Their Fabrication <s> A simple method to fabricate nanowires with radii as small as 90nm from compound-glass fibres is described. Low transmission losses at 1.55µm have been achieved in nanowires fabricated from lead-silicate and bismuth silicate optical fibres. <s> BIB002 </s> A Review of Multimode Interference in Tapered Optical Fibers and Related Applications <s> TOF Structures and Their Fabrication <s> Using a ceramic thermoelectric heater, we show highly reproducible fabrication of single-mode subwavelength silica tapers with an ultralow loss level. The reproducibility of the process is studied statistically, leading to an average taper transmission of 94%. The best tapers have a transmission superior to 99%, above the level commonly reached by other fabrication methods. The taper profile is inspected along its length and closely follows the exponential profile predicted by the model of Birks and Li. This high degree of control over the taper shape allows a detailed analysis of the transition to the single-mode regime during tapering. As an application of this fabrication method, we present a microlooped taper probe for evanescent coupling experiments requiring fine spatial selectivity. <s> BIB003 </s> A Review of Multimode Interference in Tapered Optical Fibers and Related Applications <s> TOF Structures and Their Fabrication <s> A fiber-tip high-temperature sensor based on multimode interference is demonstrated both theoretically and experimentally. The temperature sensor presented can measure a broad temperature interval ranging from room temperature to 1089°C. An average sensitivity of 11.4 pm/°C is achieved experimentally. <s> BIB004
Generally, TOF structures are fabricated by heating and tapering regular-size optical fiber BIB001 . The common techniques used in practical experiments include the flame brushing technique BIB002 , the ceramic microheater brushing technique BIB003 and CO 2 laser irradiation BIB004 . The parameters of the TOF, such as tapered waist diameter and the transition length between regular and tapered fibers, can be determined by controlling the hot region length and heating time. Here, several TOF structures addressed in our previous papers are reviewed, ranging from the STMS fiber structure, SPS fiber structure to MFC. Their fabrication techniques and theoretical analysis are also presented. It is useful to start this section on TOF structures which exploit multimodal interference with an overview of the fundamental principles of propagation in an untapered SMS structure as precursor to a similar overview of the operating principles of a tapered SMS structure, described subsequently. Generally, TOF structures are fabricated by heating and tapering regular-size optical fiber BIB001 . The common techniques used in practical experiments include the flame brushing technique BIB002 , the ceramic microheater brushing technique BIB003 and CO2 laser irradiation BIB004 . The parameters of the TOF, such as tapered waist diameter and the transition length between regular and tapered fibers, can be determined by controlling the hot region length and heating time. Here, several TOF structures addressed in our previous papers are reviewed, ranging from the STMS fiber structure, SPS fiber structure to MFC. Their fabrication techniques and theoretical analysis are also presented. It is useful to start this section on TOF structures which exploit multimodal interference with an overview of the fundamental principles of propagation in an untapered SMS structure as precursor to a similar overview of the operating principles of a tapered SMS structure, described subsequently.