The performance of fused fiber couplers is wavelength dependent. Wavelength spectral compensation is a technique to decrease the effect of the wavelength dependence, which is an essential task for many applications in fiber optic communication systems. Fiber devices such as wavelength-flattened couplers (WFCs) can be fabricated using wavelength spectral compensation methods. In this dissertation, wavelength spectral compensation techniques in fused biconical taper (FBT) couplers including both multimode and single-mode fiber couplers are studied in detail. In multimode fiber coupler operation, a novel theoretical model based on frustrated total internal reflection (FTIR) has been developed to effectively describe the power coupling and loss mechanism. Experimental results support the theoretical predictions. In single-mode fiber couplers, the conventional technique of fabricating WFCs is discussed. An alternative analytical model has been developed based upon coupled mode theory, which provides a relatively simple and mathematically sound explanation to the wavelength spectral compensation. Aiming to simplify WFC fabrication, a new way of constructing WFCs is proposed and demonstrated by connecting regular single-mode fiber couplers, some of which serve as wavelength spectral compensators. WFCs of various structures including 2x2, 1x3, 1x2ᴺ, and 4x4 have been developed, and the experimental data agree with theoretical predictions of performance. Potential applications and future research directions in wavelength spectral compensation are also presented. / Ph. D.

<p>U ovoj doktorskoj disertaciji dat je predlog nove metode za merenje talasne dužine monohromatske svetlosti pomoću spektralno osetljivih optičkih komponenti. Princip rada predložene metode se zasniva na kombinovanju spektralnih osetljivosti fiber-optičke račve i dva različita fotodetektora.<br />Izvršena je implementacija i karakterizacija senzorskog sistema za merenje talasne dužine monohromatske svetlosti. U eksperimentalnoj postavci korišćena je 2&times;2 fiber-optička račva, germanijumska (Ge) fotodioda i indijum-galijum-arsenid (InGaAs) fotodioda. Postignuta je linearnost sa faktorom korelacije R2=0.99942 i merna rezolucija od 17 pm u opsegu talasnih dužina svetlosti od 1575 do 1615 nm (L-opseg). U istom opsegu, dobijena je merna greška od približno &plusmn;0.2 nm i ponovljivost od &plusmn;0.16 nm. Ispitani su uticaji promena temperature, snage optičkog izvora i šuma na karakteristike senzorskog sistema.</p> / <p>In this thesis, a new method for measurement of monohromatic light<br />wavelength by using wavelength-dependent optical components is proposed.<br />The principle of operation of the proposed method is based on combining<br />spectral sensitivities of fiber-optic coupler and two different photodetectors.<br />Sensor system for measurement of monochromatic light wavelength is<br />implemented and characterized. Experimental setup consists of 2&times;2 fiberoptic<br />coupler, germanium (Ge) photodiode and indium-gallium-arsenide<br />(InGaAs) photodiode. Excellent linearity (R2=0.99942) and measurement<br />resolution of 17 pm are achieved in measurement range 1575-1615 nm (Lband).<br />In the same measurement range, measurement error of approximately<br />&plusmn;0.2 nm and repeatibility of &plusmn;0.16 nm are obtained. The influence of<br />temperature, optical source power and noise on sensor system characteristics<br />is investigated.</p>