Microring resonators are a fundamental building block for integrated optical filters, and have both modulation and waveform generation applications. A hybrid chalcogenide (As2S3) on titanium diffused (Ti:LiNbO3) waveguide platform has been developed to realize tunable microring resonators on a lithium niobate (LiNbO3) substrate. The use of a LiNbO3 substrate allows for electro-optic tuning, which is demonstrated for the first time on an As2S3 guided optical mode. While optical modes confined in diffused waveguides are commonly electro-optically tuned, the use of a rib waveguide external to the substrate poses new design challenges. Simulation work to determine the optimum electrode design was carried out, while also taking into account the limitations of working with a low melting temperature chalcogenide material. The tuning of this hybrid As2S3 on Ti:LiNbO3 device structure is demonstrated with fabricated Mach-Zehnder interferometers and ring resonators. Electro-optic tuning of the TM polarization utilizing the r13 LiNbO3 tuning coefficient is shown, yielding results that show an improvement over previous tunable LiNbO3 microring resonators. Simulations are also carried out to show the waveform generating capabilities of this hybrid device platform.

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Fabry-Perot interferometer (FPI) devices are designed based on the electro-optic (EO) activities of nonlinear optical (NLO) polymer materials for tunable optical filters (TOFs) and spatial light modulators (SLMs). The performance of the EO polymer based FPI devices is theoretically modeled with first order approximation on the FPI cavity interface phase dispersion. NLO materials including TCBD coupled hybrid sol-gel, AJL8/amorphous polycarbonate (APC), and AJLS102/APC are incorporated in FPI structures with distributed Bragg reflector mirrors and transparent conducting oxide electrodes for TOFs. High finesse (over 200), low drive voltage (10 dB isolation ratio with 5 V), and fast settling time (about sub-millisecond) are achieved. The physical origin of the large tunabilities is explored and the contributions from EO effect and inverse piezoelectric effect are analyzed. EO polymer SWOHF3ME/APC is employed in FPI devices with simplified structures for SLMs. Modulation beyond megahertz level is achieved with constant modulation ratio from DC frequency to high operation speed. The operation speed can be potentially over gigahertz with improved device and drive circuit design. When the EO polymer based SLM is configured to work at near the resonance band of the NLO material, the spectral tunability is increased due to resonance enhanced EO activity and the SLM performance is significantly improved. The EO polymer based FPI devices can be further optimized and are promising candidates for many optoelectronic applications.

The thesis deals with the method for the improvement of the measurement accuracy in the optical frequency spectra measurements based on tunable optical filters. The thesis starts with the selection of the proper optical filter that is suitable for accurate light spectrum measurement. The selected filter was then used for the design and realization of the measurement system for the inspection of the fibre Bragg gratings. The system incorporates a reference block for the compensation of environmental influences, an interferometric verification subsystem and a PC - based control software implemented in LabView. The preliminary experimental verification of the measurement principle and the measurement system functionality were carried out on a testing rig with a specially prepared concrete console in the UJV Řež. Advanced tests were conducted on nuclear power plant’s containment shape deformation measurement in Temelin.

L’augmentation des débits des réseaux WDM impose des contraintes de plus en plus restrictives sur les composants optiques qui les constituent. La maîtrise rigoureuse des phénomènes tels que la dispersion chromatique ou la sensibilité à la polarisation prend une importance capitale. Dans le cas des filtres optiques, la combinaison de la réduction de la bande passante et de l'accentuation des pentes tend à faire apparaître des effets auparavant négligeables. La société Yenista Optics rencontre des difficultés à contrôler la perte dépendante de la polarisation (PDL) de ses filtres au cours du processus de fabrication. L’objectif de cette thèse est de définir une méthode permettant de caractériser correctement un filtre optique dit ultrafin, c'est à dire dont la bande passante est de l'ordre de la dizaine de picomètres et les pentes de l'ordre de plusieurs centaines de dB par nanomètre. / The increasing bit rate of WDM networks strengthens the constraints on the optical devices which constitute them. Strict monitoring of phenomena such as chromatic dispersion and polarization sensitivity becomes critical. In the case of optical filters, bandwidth reduction combined with steeper roll-offs unveil effects which were previously negligible. The Yenista Optics company encounters difficulties to control the polarization dependent loss of its optical filters during the manufacturing process. The goal of this thesis is to define a method which allows to accurately characterize polarization dependent loss of ultra-narrowband filters, that is filters whose the bandwidth is a few tens of picometers and the steepness is several hundreds of decibels per nanometer.

Technology is rapidly becoming more compact and engineers are investigating new applications that are possible with this compact technology. For example photography has recently become an obvious part in our lives due to the shrinking of cameras. If there was a way to implement a light spectrum sensor into our phones there are a lot of applications this could be used for. For example the visual light spectrum can be used to detect the difference between materials in ways that our eyes can not. It could also be used to detect the amount of UV-light when outdoors or be used as an infrared camera. In order for this to be possible the spectrum sensor can’t be too big which makes the common spectrometer a bad choice for the application. This thesis compares two methods of detecting visual light spectrum suitable for On-Chip applications. One method utilize well-defined optical filters while the other works by incorporating an algorithm that boosts the performance of less well-defined optical filters. A simulation was created to assess the performance of the methods and one of these spectrometers were then designed into a circuit board to test the performance in real environments. The results concluded that the algorithmic method currently has better performance to the same price but that the purely optically filtered method is set to be stronger in the future. / Dagens teknik blir snabbt mer kompakt och ingenjörer undersöker nya tillämpningar som är möjliga med den här kompakta tekniken. Till exempel fotografi har nyligen fått en självklar plats i våra liv när kameratekniken blivit mindre. Om det fanns ett sätt att implementera en ljusspektrumsensor i våra telefoner så hade det funnits en mängd applikationer för detta. Till exempel så kan ljusspektrumet användas för att märka skillnad på material som våra ögon inte kan. Det kan också användas för att mäta mängden UV-ljus när man är ute, eller användas som en infraröd kamera. För att det här ska vara möjligt så kan inte spektrumsensorn vara alltför stor vilket gör en traditionell spektrometer blir olämplig. Den här avhandlingen jämför två metoder för att mäta det synliga ljusspektrumet som är passande för att placeras direkt på ett kretskort. En metod använder specifika optiska filter medan den andra metoden använder en algoritm för att förbättra utslaget hos mindre specifika optiska filter. En simulation skapades för att bedöma de två metoderna och ett kretskort designades sedan för att implementera en av spektrometrarna på och testa beteendet i verkliga miljöer. Resultaten visade att den algoritmiska metoden just nu har bättre prestanda men att den rent optiskt filtrerade metoden troligtvis kommer vara starkare i framtiden.

Visual inspection is a crucial final step when manufacturing products, as it determines if a product can be sold or rejected. The inspection is often performed manually by trained inspectors, which is time-consuming and often subjective. By automating the inspection, it can be performed faster and more accurately. Additionally, with faster and better results from inspection, faults in production can be noticed quickly and prevented, thus saving both money and resources. The automation often involves capturing images of the productand then analysing the images with a computer program. When capturing the images, the product must be in focus and under correct lighting. This master thesis set out to compare autofocus methods in the context of capturing images of optical filters for inspection. As the optical filters were highly reflective in the visual spectrum, the comparison was limited to autofocus methods proven to work on reflective surfaces. The literature proposes four autofocus methods for reflective surfaces. These four methods were compared regarding time, resolution, and working range. As these methods were designed for microscopes with high amplification and limited working range, they were overly complex and not applicable to the context of capturing images of optical filters. Therefore a more straightforward method with a lower resolution and larger working range that uses readily available components is proposed. The proposed method is a hybrid method using light triangulation and contrast detection, two standard autofocus methods for matte surfaces. The light triangulation quickly gives a rough focus, and then the final focus can iteratively be found with contrast detection. In the tests performed, the proposed method found focus and captured an image within 12 seconds. The proposed method achieved a resolution of just over 0.1 millimetres with a working range of 200 millimetres. / Visuell inspektion är ett avgörande sista steg under tillverkning, då det avgör ifall en produkt kan säljas eller ska kasseras. Inspekitonen genomförs ofta manuellt av tränade inspektörer vilket är tidskrävande och ofta subjektivt. Genom att automatisera inspektionen kan den genomföras snabbare och mer exakt. Dessutom med snabbare och bättre resultat från inspektionen så kan fel under produktionen upptäckas tidigt och förebyggas vilket sparar både pengar och resurser. Automatiseringen genomförs ofta genom att bilder på produkten tas och analyseras med ett datorprogram. När bilderna tas så är det viktigt att produkten är i fokus och under rätt belysning.  I detta mastersarbete så jämfördes olika autofokusmetoder i samband med att ta bilder på optiska filter för inspektion. Då de optiska filtren är högreflektiva i det synliga spektrumet så begränsades metoderna i jämförelsen till metoder som har visats fungera på reflektiva ytor. Litteraturen föreslår fyra autofokusmetoder för reflektiva ytor. Dessa fyra metoder jämfördes med avseende på tid, upplösning och arbetsområde. Då dessa metoder var designade för mikroskop med hög förstoring och begränsat arbetsområde så blev det tydligt att de var alltför komplicerade och inte applicerbara i samband med att ta bilder på optiska filter. Därför föreslås en enklare metod med lägre upplösning och större arbetsområde som använder lättillgängliga komponenter.  Den föreslagna metoden är en hybridmetod som använder ljustriangulering och kontrastdetektering, två vanliga autofokusmetoder för matta ytor. Ljustrianguleringen ger snabbt ett ungefärligt fokus och därefter kan det slutliga fokuset iterativt tas fram med kontrastdetektering. I testerna som genomfördes så hittade den föreslagna metoden korrekt fokus och en bild togs inom 12 sekunder. Metoden uppnådde en upplösning på drygt 0,1 millimeter och ett arbetsområde på 200 millimeter.

This paper attempts to use image processing methods to reduce the influences of ambient light and scattering effect on the performance of an underwater range finder. The Taguchi method, as well, is employed to increase the repeatability of underwater range finding. In this study, the image processing methods of the least-squares approximation, brightness and contrast adjustment, and primary color processing are presented. The illumination center is also used to estimate the position of the laser spot in the image. In addition, a bandpass optical filter at the receiving end is used to investigate the effects of filters on the quality of range finding. To verify the effectiveness of the proposed image processing methods, a series of DOE process runs are carried out to study effects of the design parameters on quality of range finding. For each image processing method, its corresponding control factors and levels are assigned to an inner orthogonal array. To make the proposed image processing methods robust against noises, both environmental illumination and turbidity are forced into the experiments by utilizing an outer orthogonal array. Images for processing are then captured under different noise conditions in accordance with the allocation of the outer noise array. And, according to the layout of the inner array, the S/N ratio of each treatment combination is calculated. After that, the optimum combination of control factors is predicted through the analysis of variance. Then, the confirmation experiments are carried out to verify that the combination of control factors at the perceived best levels is valid. Based on the results of experiments and analyses, it is found that the least-squares approximation is better than other proposed image processing methods for increasing the quality of range finding. Moreover, the effect of increasing quality of range finding by using the least-squares approximation is superior to that of using a bandpass optical filter. Even though a range finding system has incorporated a bandpass optical filter for filtering out unwanted noises, the quality of range finding can still be increased distinctly while the algorithm of the least-squares approximation is employed. As well, the least-squares approximation is feasible to reduce the scattering effects in the laser images if the size of the sparse backscattering light spot is smaller than that of the target light spot.

Σκοπός της διπλωματικής είναι η κατασκευή συστήματος που θα δημιουργεί φασματική απεικόνιση αντικειμένων χρησιμοποιώντας μια απλή ψηφιακή φωτογραφική μηχανή και φίλτρα τα οποία θα εναλλάσσονται μπροστά στον φακό της μηχανής με την βοήθεια βηματικού κινητήρα. / The aim of the project is the construction of a system that creates spectral imaging objects using a simple digital camera and filters which rotates in front of the camera lens by means stepper motor.