Photonic generation of ultra-low phase noise and frequency-tunable microwave or millimeter-wave (mm-wave) signals has been a topic of interest in the last few years. Advanced photonic techniques, especially the recent advancement in photonic components, have enabled the generation of microwave and mm-wave signals at high frequencies with a large tunable range and ultra-low phase noise. In this thesis, techniques to generate microwave and mm-wave signals in the optical domain are investigated, with an emphasis on system architectures to achieve large frequency tunability and low phase noise. The thesis consists of two parts. In the first part, techniques to generate microwave and mm-wave signals based on microwave frequency multiplication are investigated. Microwave frequency multiplication can be realized in the optical domain based on external modulation using a Mach-Zehnder modulator (MZM), but with limited multiplication factor. Microwave frequency multiplication based on external modulation using two cascaded MZMs to provide a larger multiplication factor has been proposed, but no generalized approach has been developed. In this thesis, a generalized approach to achieving microwave frequency multiplication using two cascaded MZMs is presented. A theoretical analysis leading to the operating conditions to achieve frequency quadrupling, sextupling or octupling is developed. The system performance in terms of phase noise, tunability and stability is investigated. To achieve microwave generation with a frequency multiplication factor (FMF) of 12, a technique based on a joint operation of polarization modulation, four-wave mixing and stimulated-Brillouin-scattering-assisted filtering is also proposed. The generation of a frequency-tunable mm-wave signal from 48 to 132 GHz is demonstrated. The proposed architecture can even potentially boost the FMF up to 24. In the second part, techniques to generate ultra-low phase noise and frequency-tunable microwave and mm-wave signals based on an optoelectronic oscillator (OEO) are studied. The key component in an OEO to achieve low phase noise and large frequency-tunable operation is the microwave bandpass filter. In the thesis, we first develop a microwave photonic filter with an ultra-narrow passband and large tunability based on a phase-shifted fiber Bragg grating (PS-FBG). Then, an OEO incorporating such a microwave photonic filter is developed. The performance including the tunable range and phase noise is evaluated. To further increase the frequency tunable range, a technique to achieve microwave frequency multiplication in an OEO is proposed. An mm-wave signal with a tunable range more than 40 GHz is demonstrated.

Photonic generation of ultra-low phase noise and frequency-tunable microwave or millimeter-wave (mm-wave) signals has been a topic of interest in the last few years. Advanced photonic techniques, especially the recent advancement in photonic components, have enabled the generation of microwave and mm-wave signals at high frequencies with a large tunable range and ultra-low phase noise. In this thesis, techniques to generate microwave and mm-wave signals in the optical domain are investigated, with an emphasis on system architectures to achieve large frequency tunability and low phase noise. The thesis consists of two parts. In the first part, techniques to generate microwave and mm-wave signals based on microwave frequency multiplication are investigated. Microwave frequency multiplication can be realized in the optical domain based on external modulation using a Mach-Zehnder modulator (MZM), but with limited multiplication factor. Microwave frequency multiplication based on external modulation using two cascaded MZMs to provide a larger multiplication factor has been proposed, but no generalized approach has been developed. In this thesis, a generalized approach to achieving microwave frequency multiplication using two cascaded MZMs is presented. A theoretical analysis leading to the operating conditions to achieve frequency quadrupling, sextupling or octupling is developed. The system performance in terms of phase noise, tunability and stability is investigated. To achieve microwave generation with a frequency multiplication factor (FMF) of 12, a technique based on a joint operation of polarization modulation, four-wave mixing and stimulated-Brillouin-scattering-assisted filtering is also proposed. The generation of a frequency-tunable mm-wave signal from 48 to 132 GHz is demonstrated. The proposed architecture can even potentially boost the FMF up to 24. In the second part, techniques to generate ultra-low phase noise and frequency-tunable microwave and mm-wave signals based on an optoelectronic oscillator (OEO) are studied. The key component in an OEO to achieve low phase noise and large frequency-tunable operation is the microwave bandpass filter. In the thesis, we first develop a microwave photonic filter with an ultra-narrow passband and large tunability based on a phase-shifted fiber Bragg grating (PS-FBG). Then, an OEO incorporating such a microwave photonic filter is developed. The performance including the tunable range and phase noise is evaluated. To further increase the frequency tunable range, a technique to achieve microwave frequency multiplication in an OEO is proposed. An mm-wave signal with a tunable range more than 40 GHz is demonstrated.

La génération de signaux microondes à grande pureté spectrale est fondamentale pour différentes applications (systèmes RADAR, échantillonnage large bande). L’optique propose des solutions prometteuses pour la montée en fréquence des d’oscillateurs à bas bruit de phase. L’objectif de cette thèse est d’étudier différentes configurations d’oscillateurs optoélectroniques (OEO) à 10 GHz. Pour cela, nous avons développé puis validé expérimentalement un modèle décrivant le bruit de phase, que nous avons ensuite étendu aux OEOs à boucles multiples. Cet outil unique nous a permis de concevoir un OEO à double boucles à l’état de l’art avec un encombrement réduit (premier mode parasite avec un niveau de bruit de phase de -146 dBc/Hz à 187 kHz de la porteuse). Nous avons également étudié des OEOs à amplification optique qui permettent de lever les verrous associés aux amplificateurs RF lors de la montée en fréquence (contribution de bruit et bande passante) tout en conservant d’excellentes performances. Enfin, nous nous sommes intéressés aux oscillateurs optoélectroniques couplés (COEOs), qui associent un laser à verrouillage de modes à un OEO. Nous avons modélisé le bruit de phase du laser en tenant en compte pour la première fois la non-orthogonalité des modes de la cavité, puis initié un modèle pour le COEO. Après une étude expérimentale des paramètres clef, nous avons réalisé un COEO proche de l’état de l’art, dont le bruit phase au voisinage de la porteuse est amélioré par rapport aux OEOs pour des longueurs de boucle plus courtes. / High purity microwave signal generation is required in various applications (RADAR systems, wideband sampling). For high frequency operations, optics offer promising solutions to generate low noise oscillators. The objective of this thesis consists in studying various optoelectronic oscillator (OEO) configurations at 10 GHz. We first worked on a phase noise model and its experimental validation, further extended to multiple loop OEOs. This comprehensive model allowed the design of a state-of-the-art dual loop OEO with consideration to its compactness (first spur located at 187 kHz from the carrier with a phase noise level of 146 dBc/Hz).We then focused on all photonic gain OEOs to get rid of RF amplifiers whose bandwidth and noise contributions are a limit for high frequency operations. Finally, we studied coupled optoelectronic oscillators (COEOs) which may simply be described as a combination of a mode locked laser and an OEO. We worked on a phase noise model for active and harmonically mode locked laser taking into account for the first time the non-orthogonality of the cavity modes. This model is the basis to a COEO model we began to develop. After experimentally determining key parameters, we designed and optimized a low noise COEO exhibiting a close-to-carrier phase noise similar to the state-of-the-art.

<p>Two experimentswere  conducted  using  pigs  at different  life stages to  determine  the  effects  of dietary  tryptophan  and  water  delivered  oregano  essential  oil  on growth performance, rectal temperature, water use,intestinal integrity and gene expression of biomarkers in the face heat or transport stress. In the first experiment, 192 grow-finish pigs were used to investigate the effects of  water  supplementation  of  oregano  essential  oil  (OEO)  on  growth  performance,  water  intake, rectal temperature, intestinal integrity, and expression of genetic biomarkers during an acute heat challenge. Pigs were randomly allotted to 2 X 2 factorial arrangement of treatments with pigs being heat  stressed  or  not  and  being  supplemented  with  OEO  or  not with 8  replicate  pens  of  each treatment  with  6  pigs/pen  (4  barrows,  2  gilts  per  pen).  Water  treatments  were administered immediately, with  dosing at  47 μL/L of OEO. One-half  of  the  pigs  on  each  water  treatment remained under thermoneutral conditions (TN; 21.1C), while the other half was subjected to a 3 d diurnal, acute heat stress (HS) with 12 hours at 33.3 oC (7AM-7PM) and 12 hours at 26.7oC (7PM-7AM). Three days post-HS, temperatures were reduced back to TN for the rest of the study, and pigs remained on their water treatments. Rectal temperatures were collected in the morning and evening  of  the  heat  stress  period  on  one  barrow  and  one  gilt  in  each  pen. Jejunal  tissue was collected for subsequent histological examination and determination of gene expression. All data were  analyzed  using  the  GLM  procedure  of  SAS  (ver.  9.4).  Pigs  subjected  to  heat  stress  had reduced ADG (P < 0.003) and G:F (P < 0.008) during the 3d heat stress compared to pigs reared under thermoneutral conditions. However, post-heatstress, heat stressed pigs had compensatory gain resulting in increased ADG (P < 0.001) and G:F (P < 0.001) compared to thermoneutral reared pigs.   Overall,  there  was an  interaction  (P  <  0.006)  observed  between  water  and  heat  treatment with  OEO  increasing  ADG  in  thermoneutral  pigs  but  not  in  heat  stressed  pigs.  Similarly, interactions  between  water  and  heat  treatment  were  observed  for  ADFI  during  heat  stress  (P  < 0.004),  post  heat  stress  (P  <  0.01),  and  overall  (P  <  0.004)  from  increasing  OEO  intake  in thermoneutral pigs but not in heat stressed pigs. Rectal temperatures were higher (P < 0.001) for heat stressed pigs at the end of d 1 and 2 of the acute heat challenge compared to TN housed pigs. Pigs exposed to HS also used more water than pigs housed in a thermoneutral environment (P < 0.002). There were no differences between villi height, crypt depth or VH:CD between treatment groups  (P  >0.05).  There  was  also  no  difference  in  TP53  and  CDKNA1  gene  expression  among treatments (P > 0.10). In the second experiment, 36 barrows were used in an 18d experiment to investigate the effects of pre-weaning tryptophan supplementation on performance and intestinal integrity following  weaning  with  or  without  transport  stress  at  weaning.  Pigs  were  randomly allotted to 2 X 2 factorial arrangement of treatments of pre-weaning tryptophan supplementation or not and weaning transport or not. Pigs on the tryptophan treatment received 0.35, 0.45, and 0.55 g Trp/d in 5 day intervals, beginning 15 d prior to weaning.Tryptophan was dissolved in chocolate milk and administered by oral gavage with control pigs receiving milk only. At weaning, 4 pigs from each pre-weaning treatmentwere euthanized for collection of jejunal tissue.  Of the remaining pigs, half the pigs oneach treatment were transported for 12 h, and half were moved into individual pens  with  no  transport.  Following  transport,  all  pigs  were  individually  housed  and  provided  ad libitum  access  towater  andfeed  from  a  common  diet.  On  d  3  post-weaning,  all  pigswere euthanized for collection of jejunal tissue. Jejunal tissue was used for histological examination and for determination of gene expression. All data were analyzed using the GLM procedure of SAS (9.4).  No  effects  of  Trp  supplementation  were  observed  on  pre-weaning  (P  >  0.10)  growth. Pig BW and ADFI were unaffected (P > 0.10) by Trp supplementation and transport at weaning. Post-weaning, there was a tendency (P < 0.06) for an effect of transport on ADG as transported pigs lost weight in the 3 d post-weaning period while non-transported pigs gained slightly. Gain:Feed post-weaning  was  lower  (P  <  0.04)  for  transported  pigs  compared  to  non-transported  pigs.  No differences  were  observed  for villus base  and  mid  width,  villus  height,  crypt  depth  or  villus height:crypt   depth.   There   was   a   tendency   for   an   interaction   of   transportation   and   Trp supplementation  (P  <  0.06)  on  villi  base  width  driven  by  an  increased  villus  width  in  non-transported pigs given supplemental Trp but a decrease in villus width in transported pigs given supplemental Trp.These results conclude that these alleviating agents had minimal effects when pigs  were  stressed, however TN grow-finish pigs  benefitted  from  OEO  water  supplementation among growth performance.</p>

L'optique constitue aujourd'hui une solution performante pour la réalisation de sources très pures en hyperfréquences, en particulier grâce à l'approche de l'oscillateur électro-optique (OEO). La pureté spectrale de ces sources est essentielle pour les applications spatiales, militaires et pour la métrologie du temps et des fréquences. Durant cette thèse, nous avons réalisé et étudié différents types d'OEO à résonateur optique en vue d'optimiser le bruit de phase de ce système. Nous avons en particulier orienté nos travaux vers une approche originale utilisant un anneau résonant fibré (ARF) passif. Ce type de résonateur présente en effet des coefficients de qualité optiques supérieurs à 109 pour des longueurs de fibre restant relativement faibles (L ~ 10 m) et facilement intégrables dans un support planaire. En parallèle, nous avons mené un travail important sur les oscillateurs à base de résonateurs optiques 3D. Concernant l'OEO à ARF, des progrès spectaculaires ont pu être obtenus grâce à une meilleure compréhension des phénomènes de bruit intrinsèques à ce système. Les deux types de bruit prépondérants étaient la conversion du bruit du laser (FM et AM) en bruit de phase RF par différentes non-linéarités (dont la photodiode) et le déclenchement d'effets non-linéaires optiques à l'intérieur du résonateur. Le contrôle de ces effets a permis en particulier d'éliminer des remontées importantes de bruit sur le spectre de l'oscillateur, et d'atteindre un niveau de bruit de phase de -128 dBc/Hz à 10 kHz de la porteuse à 10.2 GHz en utilisant un OEO à base d'un ARF passif de 100 mètres de longueur, optimisé et immunisé contre les effets non-linéaires optiques.