THz and mm-wave technology has become increasingly significant in a very diverse range of applications such as spectroscopy, imaging, and communication as a consequence of a plethora of significant advances in this field. However to achieve a mass production of THz systems, all the commercial aspects should be considered. The main concerns are attributed to the robustness, compactness, and a low cost device. In this regard, research efforts should be focused on the elimination of obstacles standing in the way of commercializing the THz technology. To this end, in this study, low cost fabrication technologies for various parts of mm-wave/THz systems are investigated and explored to realize compact, integrated, and rugged components. This task is divided into four phases. In the first phase, a robust fiber-based beam delivery configuration is deployed instead of the free beam optics which is essential to operate the low cost THz photomixers and photoconductive antennas. The compensation of different effects on propagation of the optical pulse along the optical fiber is achieved through all-fiber system to eliminate any bulky and unstable optical components from the system. THz measurements on fiber-coupled systems exhibit the same performance and even better compared to the free beam system. In the next phase, the generated THz wave is coupled to a rectangular dielectric waveguide through design of a novel transition with low insertion loss. The structure dimensions are reported for various range of frequencies up to 650GHz with insertion loss less than 1dB. The structure is fabricated through a standard recipe. In third phase, as consequence of the advent of high performance active device at mm-wave and THz frequency, a transition is proposed for coupling the electromagnetic wave to the active devices with CPW ports. Different approaches are devised for different frequencies as at higher frequencies any kind of metallic structure can introduce a considerable amount of loss to the system. The optimized structures show minimum insertion loss as low as 1dB and operate over 10% bandwidth. The various configurations are fabricated for lower frequencies to verify the transition performance. The last phase focuses on the design, optimization, fabrication and measurements of a new dielectric side-grating antenna for frequency scanning applications. The radiation mechanism is extensively studied using two different commercial full-wave solvers as well as the measured data from the fabricated samples. The optimized antenna achieves a radiation efficiency of 90% and a gain of 18dB. The measured return loss and radiation pattern show a good agreement with the simulation results.

This paper reports a reciprocal Mach-Zehnder interferometer in a dual Sagnac ring configuration, and one of two arms in Mach-Zehnder interferometer is used for underwater optic fiber hydrophone. Two Mach-Zehnder interferometers operated in opposite sense are simultaneously induced from the underwater acoustic wave and the PZT phase modulation. Thus, at the output, four interferometric beams occur such that the intensity of interferometric beams will enhance. In general, one stage of a double Mach-Zehnder interferometer is just used as a sensor, another one for compensation. Specially, this paper presents two stages of a double Mach-Zehnder interferometer sense the measurand at the same time due to the topology structure of Sagnac ring pairs. In the other words, the characteristic is to win the affection of two beauties at the same time. Two rings in the same direction make a Mach-Zehnder interferometer. Besides, the inner ring in the clockwise direction and the outer one in the counterclockwise direction also make a Mach-Zehnder interferometer. So as to the unbalanced arms of the Mach-Zehnder interferometer, the underwater acoustic wave induces the light beam phase difference in optic fiber hydrophone interrogator to demodulate the acoustic wave signal by PGC circuit.

Large on-chip bandwidths required for high performance electronic chips will render optical components essential parts of future on-chip interconnects. Silicon photonics enables highly integrated photonic integrated circuit (PIC) using CMOS compatible process. In order to maximize the bandwidth density and design flexibility of PICs, vertical integration of electronic layers and photonics layers is strongly preferred. Comparing deposited silicon, single crystalline silicon offers low material absorption loss and high carrier mobility, which are ideal for multi-layer silicon PIC. Three different methods to build multi-layer silicon PICs based on single crystalline silicon are demonstrated in this dissertation, including double-bonded silicon-on-insulator (SOI) wafers, transfer printed silicon nanomembranes, and adhesively bonded silicon nanomembranes. 1-to-12 waveguide fanouts using multimode interference (MMI) couplers were designed, fabricated and characterized on both double-bonded SOI and transfer printed silicon nanomembrane, and the results show comparable performance to similar devices fabricated on SOI. However, both of these two methods have their limitations in optical interconnects applications. Large and defect-free silicon nanomembrane fabricated using adhesive bonding is identified as a promising solution to build multi-layer silicon PICs. A double-layer structure constituted of vertically integrated silicon nanomembranes was demonstrated. Subwavelength length based fiber-to-chip grating couplers were used to couple light into this new platform. Three basic building blocks of silicon photonics were designed, fabricated and characterized, including 1) inter-layer grating coupler based on subwavelength nanostructure, which has efficiency of 6.0 dB and 3 dB bandwidth of 41 nm, for light coupling between layers, 2) 1-to-32 H-tree optical distribution, which has excess loss of 2.2 dB, output uniformity of 0.72 dB and 3 dB bandwidth of 880 GHz, 3) waveguide crossing utilizing index-engineered MMI coupler, which has crossing loss of 0.019 dB, cross talk lower than -40 dB and wide transmission spectrum covering C-band and L-band. The demonstrated integration method and silicon photonic devices can be integrated into the CMOS back-end process for clock distribution and global signaling. / text

This thesis focuses on two topics: thermal limitations of volume Bragg gratings (VBGs) employed as laser-cavity mirrors and formation of color centers in KTiOPO4 and its isomorphs. To explore the mechanisms of the thermal limitations of VBGs in high power lasers, I designed and constructed a diode-pumped, solid‑state laser with a VBG as cavity mirror that had a significantly higher absorption than what is typical. Thereby I could study the limiting thermal effects by using only moderate intra-cavity power. Additionally, I designed a computer model to numerically investigate the thermal effects in VBGs. Both the experiments and the simulations showed that the laser became successively more unstable when the power was increased. Absorption of the reflected laser beam causes broadening of the grating spectrum accompanied by decreasing diffraction efficiency. The reduced reflectivity leads to a leakage of the radiation through the grating. Moreover, the simulations showed that this increased instability was due to a reshaping of the intensity distribution profile inside the grating, which, in turn, leads to a sharp reduction of the diffraction efficiency. High-intensity visible radiation induces color centers in KTiOPO4, which can lead to severe decrease in the performance of the crystal and can cause catastrophic breakdown. The formation of color centers was investigated by measuring picosecond, blue-light induced infrared absorption (BLIIRA) in periodically-poled KTiOPO4, Rb:KTiOPO4, RbTiOPO4, KTiOAsO4 and RbTiOAsO4 through thermal lens spectroscopy using a common-path interferometer. This setup is capable of measuring absorption as low as 10-5 cm-1. The dependence of the BLIIRA signal on blue light average power and intensity as well as on the crystal temperature was studied. The results show the presence of at least two different types of color centers. A higher level of remnant absorption was observed in the phosphates compared to that of the arsenates. The largest portion of the induced absorption is attributed to photo-generated electrons and holes being self-trapped in the proximity to the Ti4+ and O2- ions, respectively, forming polaron color centers. Stabilization of these centers is aided by the presence of mobile alkali metal vacancies in the crystal. / Denna avhandling fokuserar på både volymbraggitters (VBGs) termiska begränsningar, i tillämpning som speglar i laserkaviteter, och på bildandet av färgcentra i KTiOPO4 och isomorfa kristaller. För att undersöka de termiska effekterna i VBGer som medför begränsningar på högeffektlasrar utfördes både experiment och simuleringar. För experimenten konstruerades en diod-pumpad Yb:KYW laser med ett VBG som har betydligt högre absorption än vad som är typiskt. Därmed kunde de termiska effekterna studeras vid måttliga intrakavitetseffekter. Simuleringarna bestod av två delmodeller; gitterstrukturen modelerades med överföringsmatriser och värmeflödet med en tredimensionell modell baserad på finita elementmetoden. Både experimenten och simuleringarna visade att en laser blir successivt mer instabil när den optiska effekten ökar. Absorptionen av laserstrålen i VBGt förändrade dess spektrala egenskaper, vilket i sin tur påverkade laserns stabilitet och prestanda. De huvudsakliga effekterna var en breddning av gittrets spektrum med en minskad reflektans. Simuleringarna visade även att den ökade instabiliteten berodde på en förändring av strålningens intensitetsfördelning inuti gittret, vilket accelererade reduktionen av gittrets reflekterande förmåga. I termer av den effekt som faller in mot gittret, har lasern en tydlig övre effektgräns. När den gränsen har uppnåtts leder vidare ökning av pumpeffekten i huvudsak till ökat läckage genom volymbraggittret, i stället för till ökad uteffekt hos laserstrålen. Kortvågigt synlig ljus av hög intensitet inducerar färgcentra i KTiOPO4, vilket kan leda till kraftigt reducerad transparens och kan orsaka permanent skada i kristallen. För att undersöka skapandet av dessa färgcentra mättes den termiska lins som uppstår vid blå-ljus-inducerad infraröd absorption (Eng: blue-light induced infrared absorption = BLIIRA) inducerad av blåa laserpulser vid en våglängd av 398 nm och vid pulslängder i storlek av pikosekunder i periodiskt‑polad KTiOPO4, Rb:KTiOPO4, RbTiOPO4, KTiOAsO4 och RbTiOAsO4. Den termiska linsen mättes med en metod kallad gemensam-vägsträcka-interferometer (Eng: common-path interferometer), en metod känslig nog för att mäta absorption så låg som 10-5 cm-1. Dessutom undersöktes hur nivån av BLIIRA beror på medeleffekten och intensiteten hos den blåa laserstrålen samt på kristalltemperaturen. Resultaten visar att det bildas minst två typer av färgcentra med olika livslängder. Vidare observerades en högre grad av långsamt avklingande absorption i fosfaterna jämfört med arsenaterna. Den största delen av den inducerade absorptionen tillskrivs fotogenererade elektroner och hål som ”självfångas” i närheten av Ti4+ respektive O2- joner, och bildar färgcentra av polaron karaktär. Stabilisering av dessa centra underlättas av lättrörliga alkalivakanser i kristallerna. / <p>QC 20150922</p>

Darbe pristatomi eksperimentiniai bei teoriniai rezultatai, susiję su skaidriųjų terpių lūžio rodiklio pokyčio indukavimu. Parodoma, kad lydytą kvarcą veikiant Yb:KGV lazerine sistema generuojamais impulsais, jame galima sukurti modifikuoto lūžio rodiklio sritis. Šios sritys pasižymi dvejopu šviesos lūžimu, atsirandančiu dėl medžiagos tūryje besiformuojančių nanogardelių, o modifikuotų sričių vienalytiškumas priklauso nuo akumuliacinių efektų. Pakitusio lūžio rodiklio sritis taip pat galima formuoti ir ličio niobato kristale. Priklausomai nuo spinduliuotės parametrų, šiame kristale galima įrašyti stabilius modifikuoto lūžio rodiklio darinius, o taip pat ir nestabilias modifikacijas, atsirandančias dėl fotorefrakcinio reiškinio. Pastarąjį efektą galima panaudoti daugkartiniam informacijos įrašymui. Pademonstruoti efektyvūs fotoniniai elementai, tūrinės Brego gardelės, įrašytos tiek lydyto kvarco, tiek ličio niobato kristalo tūryje. Pateikiama metodika, skirta lazerio indukuoto lūžio rodiklio pokyčiui nustatyti matuojant Brego gardelių difrakcinius efektyvumus. Taip pat tyrinėjama kaip modifikuoti dariniai lemia superkontinuumo ir šviesos gijos formavimosi reiškinius lydytame kvarce. / The study on refractive index modification of transparent materials with ultrashort laser pulses is presented in this dissertation. Based on experimental data it was demonstrated, that using ultrashort pulses, generated with Yb:KGW laser system, it is possible to produce modified refractive index zones in the fused silica glass, that possess birefringence. This effect is caused by nanogratings that form in the bulk of the material. Homogeneity of the modified zones is determined by the accumulation effects, mainly the number of pulses that affect each area. Refractive index variations can be created also in crystalline material such as lithium niobate. Depending on the writing pulse parameters different types of modifications can be created: permanent modification that is caused by crystal amorphization and non-stable modifications that originate from the photorefractive properties of the crystal. Latter modifications can be used for three-dimensional, rewritable data recording. Highly efficient photonic elements, such as volume Bragg gratings, recorded in fused silica and lithium niobate crystal are demonstrated. The technique allowing the evaluation of refractive index change applying Bragg gratings is described. Also modification influence on nonlinear processes that appear in fused silica such as filament formation and supercontinuum generation is experimentally investigated.

The study on refractive index modification of transparent materials with ultrashort laser pulses is presented in this work. Based on experimental data it was demonstrated, that using ultrashort pulses, generated with Yb:KGW laser system, it is possible to produce modified refractive index zones in the fused silica glass, that possess birefringence. This effect is caused by nanogratings that form in the bulk of the material. Homogeneity of the modified zones is determined by the accumulation effects, mainly the number of pulses that affect each area. Refractive index variations can be created also in crystalline material such as lithium niobate. Depending on the writing pulse parameters different types of modifications can be created: permanent modification that is caused by crystal amorphization and non-stable modifications that originate from the photorefractive properties of the crystal. Latter modifications can be used for three-dimensional, rewritable data recording. Highly efficient photonic elements, such as volume Bragg gratings, recorded in fused silica and lithium niobate crystal are demonstrated. The technique, allowing the evaluation of refractive index change applying Bragg gratings, is described. Also modification influence on nonlinear processes that appear in fused silica such as filament formation and supercontinuum generation is experimentally investigated. / Darbe pristatomi eksperimentiniai bei teoriniai rezultatai, susiję su skaidriųjų terpių lūžio rodiklio pokyčio indukavimu. Parodoma, kad lydytą kvarcą veikiant Yb:KGV lazerine sistema generuojamais impulsais, jame galima sukurti modifikuoto lūžio rodiklio sritis. Šios sritys pasižymi dvejopu šviesos lūžimu, atsirandančiu dėl medžiagos tūryje besiformuojančių nanogardelių, o modifikuotų sričių vienalytiškumas priklauso nuo akumuliacinių efektų. Pakitusio lūžio rodiklio sritis taip pat galima formuoti ir ličio niobato kristale. Priklausomai nuo spinduliuotės parametrų, šiame kristale galima įrašyti stabilius modifikuoto lūžio rodiklio darinius, o taip pat ir nestabilias modifikacijas, atsirandančias dėl fotorefrakcinio reiškinio. Pastarąjį efektą galima panaudoti daugkartiniam informacijos įrašymui. Pademonstruoti efektyvūs fotoniniai elementai, tūrinės Brego gardelės, įrašytos tiek lydyto kvarco, tiek ličio niobato kristalo tūryje. Pateikiama metodika, skirta lazerio indukuoto lūžio rodiklio pokyčiui nustatyti matuojant Brego gardelių difrakcinius efektyvumus. Taip pat tyrinėjama kaip modifikuoti dariniai lemia superkontinuumo ir šviesos gijos formavimosi reiškinius lydytame kvarce.

Tyrimo objektas: kombinuoti mechaninio nuotekų valymo įrenginiai esantys Balbieriškio, Kaišiadorių, Pasvalio ir Kuršėnų nuotekų valyklose. Tyrimo tikslas: išanalizuoti kombinuotų mechaninio nuotekų valymo įrenginių taikymo galimybes, atsižvelgiant į nuotekų charakteristikas, atlikti šių įrenginių privalumų ir trūkumų analizę. Tyrimo uždaviniai: 1. Identifikuoti nuotekų valyklose esamus kombinuotus nuotekų valymo įrenginius. 2. Atrinkti nuotekų valyklas su skirtingais kombinuotais nuotekų valymo įrenginiais. 3. Išanalizuoti pasirinktose nuotekų valyklose atitekančių nuotekų charakteristikas. 4. Atlikti atrinktuose objektuose kombinuotų valymo įrenginių privalumų ir trūkumų analizę. Tyrimo metodas: ekspertinis vertinimas (vizualus vertinimas). Tyrimo rezultatai:  Trumpai aprašomi atrinkti objektai, kuriuose sumontuoti skirtingi kombinuoti mechaninio nuotekų valymo įrenginiai. Aprašomos kombainų techninės charakteristikos ir jų veikimas.  Atliekamas kombainų vertinimas pagal vertinimo kriterijus: įrenginių techninis patikimumas, valymo procesų technologinis stabilumas, valymo įrenginių kontrolės ir eksploatavimo ypatumai, valymo įrenginių priežiūros ir einamojo remonto ypatumai.  Gauti kombainų vertinimo rezultatai pagal 4 kriterijus panaudojami daugiakriterinei analizei, kuriai atlikti naudojama kompiuterinė programa DAM.  Atsižvelgiant į ekspertinio vertinimo ir daugiakriterinės analizės metu gautus rezultatus nustatyta, kad geriausias iš vertintų kombainų yra PASSAVANT... [toliau žr. visą tekstą] / Object of the research: combined mechanical wastewater treatment facilities in the wastewater treatment plants of Balbieriškis, Kaišiadoriai, Pasvalys and Kuršėnai. Aim of research: to analyse the possibilities to apply combined mechanical wastewater treatment facilities, to perform the analysis of advantages and disadvantages of those treatment systems regarding the wastewater characteristics. Objectives of the research: 1. To identify combined wastewater treatment facilities located in the wastewater treatment plants. 2. To select the wastewater treatment plants with different combined wastewater treatment facilities. 3. To analyse the characteristics of wastewater coming into the selected wastewater treatment systems. 4. To perform the analysis of advantages and disadvantages of combined treatment facilities in the selected objects. Method of the research: expert evaluation (visual evaluation). Results of the research:  A short description of the selected objects where different combined mechanical wastewater treatment systems are installed. Technical characteristics and operation of combines are described.  An evaluation of combines is performed according to the following criteria: technical reliability of systems, technological stability of treatment processes, peculiarities of treatment plant monitoring and exploitation, peculiarities of maintenance and permanent repair of treatment plant systems.  The received results of combine evaluation are used for... [to full text]

La spectroscopie Raman est un outil non destructif fort utile lors de la caractérisation de matériau. Cette technique consiste essentiellement à faire l’analyse de la diffusion inélastique de lumière par un matériau. Les performances d’un système de spectroscopie Raman proviennent en majeure partie de deux filtres ; l’un pour purifier la raie incidente (habituellement un laser) et l’autre pour atténuer la raie élastique du faisceau de signal. En spectroscopie Raman résonante (SRR), l’énergie (la longueur d’onde) d’excitation est accordée de façon à être voisine d’une transition électronique permise dans le matériau à l’étude. La section efficace d’un processus Raman peut alors être augmentée d’un facteur allant jusqu’à 106. La technologie actuelle est limitée au niveau des filtres accordables en longueur d’onde. La SRR est donc une technique complexe et pour l’instant fastidieuse à mettre en œuvre. Ce mémoire présente la conception et la construction d’un système de spectroscopie Raman accordable en longueur d’onde basé sur des filtres à réseaux de Bragg en volume. Ce système vise une utilisation dans le proche infrarouge afin d’étudier les résonances de nanotubes de carbone. Les étapes menant à la mise en fonction du système sont décrites. Elles couvrent les aspects de conceptualisation, de fabrication, de caractérisation ainsi que de l’optimisation du système. Ce projet fut réalisé en étroite collaboration avec une petite entreprise d’ici, Photon etc. De cette coopération sont nés les filtres accordables permettant avec facilité de changer la longueur d’onde d’excitation. Ces filtres ont été combinés à un laser titane : saphir accordable de 700 à 1100 nm, à un microscope «maison» ainsi qu’à un système de détection utilisant une caméra CCD et un spectromètre à réseau. Sont d’abord présentés les aspects théoriques entourant la SRR. Par la suite, les nanotubes de carbone (NTC) sont décrits et utilisés pour montrer la pertinence d’une telle technique. Ensuite, le principe de fonctionnement des filtres est décrit pour être suivi de l’article où sont parus les principaux résultats de ce travail. On y trouvera entre autres la caractérisation optique des filtres. Les limites de basses fréquences du système sont démontrées en effectuant des mesures sur un échantillon de soufre dont la raie à 27 cm-1 est clairement résolue. La simplicité d’accordabilité est quant à elle démontrée par l’utilisation d’un échantillon de NTC en poudre. En variant la longueur d’onde (l’énergie d’excitation), différentes chiralités sont observées et par le fait même, différentes raies sont présentes dans les spectres. Finalement, des précisions sur l’alignement, l’optimisation et l’opération du système sont décrites. La faible acceptance angulaire est l’inconvénient majeur de l’utilisation de ce type de filtre. Elle se répercute en problème d’atténuation ce qui est critique plus particulièrement pour le filtre coupe-bande. Des améliorations possibles face à cette limitation sont étudiées. / Raman spectroscopy is a useful and non-destructive tool for material characterization. It uses inelastic light scattering interaction with matter to investigate materials. The major part of the performances in a Raman spectroscopy system comes from two light filter units: the first shapes the light source (usually a laser) and the other attenuates the elastic scattered light in the signal beam. In resonant Raman spectroscopy (RRS), the excitation energy (wavelength) is tuned to match an electronic transition of the sample. When in resonance, the Raman cross section is increased by a factor up to 106. Current RRS setups are limited by filtering devices technology. RRS is a complex technique which, for the moment, remains tedious to implement. This master thesis presents the construction of a tunable Raman spectroscopy system based on volume Bragg gratings light filters. The setup is designed to operate in the near infrared region so as to study carbon nanotubes resonances. Steps leading to the operation of the system are described. They cover conceptualization, fabrication, characterization and optimisation of the setup. Collaboration with a local small company, Photon etc, led to the building of two new light filters that allow to tune easily the excitation wavelength. These filters have been adapted to work with a tunable titanium-sapphire laser (tunable from 700 to 1100 nm) and assembled with a homemade microscope and a detection system combining a CCD camera with a grating spectrometer. This document is arranged as follow: First are presented the theoretical aspects surrounding RRS. Carbon nanotubes (CNT) are than described to illustrate the relevance of such technique applied to material science. Principles behind the use of the Bragg filters are described to be followed by a scientific paper in which the main results of this work are presented. These include the optical characterisation of the filters and measurements with the system. Low frequency limits of the system are demonstrated using a sulphur powder where the 27 cm-1 line is clearly resolved. The tunability of the setup is also demonstrated using a bulk carbon nanotube sample. By changing the excitation wavelength, different nanotube chiralities become resonant, leading to different signals in the Raman spectra. Finally, clarifications regarding the alignment, optimisation and operation of the system are described. Low angular acceptance has been found to be the main drawback of the system leading to attenuation problems especially critical for the notch filter. Possible improvements on this limitation are discussed.

Since their discovery in 1978 by Hill et al. and the development of the transverse holographic technique for their fabrication by Meltz et al. in 1989, fiber Bragg gratings (FBG) have become an important device for applications in optical communications, optical signal processing and fiber-optical sensors. A superstructured fiber Bragg grating (SFBG), also called a sampled fiber Bragg grating, is a special FBG that consists of a several small FBGs placed in close proximity to one another. SFBGs have attracted much attention in recent years with the discovery of techniques allowing the creation of equivalent chirp or equivalent phase shifts. The biggest advantage of an SFBG with equivalent chirp or equivalent phase shifts is the possibility to design and fabricate gratings with greatly varying phase and amplitude responses by adjusting the spatial profile of the superstructure. The realization of SFBGs with equivalent chirp or equivalent phase shifts requires only sub-millimeter precision. This is a relief from the sub-micron precision required by traditional approaches. In this thesis, the mathematical modeling of FBGs and SFBGs is reviewed. The use of SFBGs for various applications in photonic microwave signal processing is considered. Four main topics are presented in this thesis. The first topic is the use of SFBG as a photonic true-time delay (TTD) beamformer for phased array antennas (PAAs). The second topic addresses non-linearities in the group delay response of an SFBG with equivalent chirp in its sampling period. An SFBG with an equivalent chirp using only a linear chirp coefficient may yield a group delay response that deviates from the linear response required by a TTD beamformer. In the thesis, a technique to improve the linearity of the group delay response is proposed and an adaptive algorithm to find the optimal linear and non-linear chirp coefficients to produce the best linear group delay response is described. Since no closed-form solution exists to represent the amplitude and phase responses of an SFBG, we rely on a Fourier transform analogy under a weak grating approximation as a starting point in the design of an SFBG. Simulations are then used to refine the response of the SFBG. The algorithm proposed provides an optimal set of chirp coefficients that minimizes the error in the group delay response. Four gratings are fabricated using the optimized chirp coefficients and their application in a TTD PAA system is discussed. The third topic discusses the use of an SFBG with equivalent phase shifts in its sampling period as a means to realize optical single sideband (SSB) modulation. SSB modulation eliminates the power penalty caused by chromatic dispersion experienced by an optical signal traveling through a long length of optical fiber. By introducing two π phase shifts through equivalent sampling to the SFBG, two ultra-narrow transmission bands are created in the grating stop band of the +/- 1st spectral orders. In the proposed system, a double-sideband plus carrier (DSB+C) modulated optical signal is sent to the input of an optical SSB filter based on the equivalent phase-shift SFBG in order to select the optical carrier and a single sideband, effectively blocking one sideband from propagating. Finally, the fourth topic focuses on the implementation of a photonic microwave bandpass filter based on an SFBG with equivalent chirp. Photonic microwave filters are used to process microwave signals in the optical domain. By using a technique called phase-modulation to intensity-modulation (PM-IM) conversion, a two-tap delay line filter is created with one negative tap. A single SFBG with a chirp in its sampling period is used as a means to achieve the PM-IM conversion for the two taps. Two phase modulated optical carriers are used to generate the two taps, each entering a different port of the SFBG and thus experiencing an opposite dispersion value. The two optical signals are then recombined before being sent to a photodetector (PD) where the filtered microwave signal is recovered.

THz and mm-wave technology has become increasingly significant in a very diverse range of applications such as spectroscopy, imaging, and communication as a consequence of a plethora of significant advances in this field. However to achieve a mass production of THz systems, all the commercial aspects should be considered. The main concerns are attributed to the robustness, compactness, and a low cost device. In this regard, research efforts should be focused on the elimination of obstacles standing in the way of commercializing the THz technology. To this end, in this study, low cost fabrication technologies for various parts of mm-wave/THz systems are investigated and explored to realize compact, integrated, and rugged components. This task is divided into four phases. In the first phase, a robust fiber-based beam delivery configuration is deployed instead of the free beam optics which is essential to operate the low cost THz photomixers and photoconductive antennas. The compensation of different effects on propagation of the optical pulse along the optical fiber is achieved through all-fiber system to eliminate any bulky and unstable optical components from the system. THz measurements on fiber-coupled systems exhibit the same performance and even better compared to the free beam system. In the next phase, the generated THz wave is coupled to a rectangular dielectric waveguide through design of a novel transition with low insertion loss. The structure dimensions are reported for various range of frequencies up to 650GHz with insertion loss less than 1dB. The structure is fabricated through a standard recipe. In third phase, as consequence of the advent of high performance active device at mm-wave and THz frequency, a transition is proposed for coupling the electromagnetic wave to the active devices with CPW ports. Different approaches are devised for different frequencies as at higher frequencies any kind of metallic structure can introduce a considerable amount of loss to the system. The optimized structures show minimum insertion loss as low as 1dB and operate over 10% bandwidth. The various configurations are fabricated for lower frequencies to verify the transition performance. The last phase focuses on the design, optimization, fabrication and measurements of a new dielectric side-grating antenna for frequency scanning applications. The radiation mechanism is extensively studied using two different commercial full-wave solvers as well as the measured data from the fabricated samples. The optimized antenna achieves a radiation efficiency of 90% and a gain of 18dB. The measured return loss and radiation pattern show a good agreement with the simulation results.