الفهرس 
BACKGROUND AND LITERATURE REVIEW
Active filter for finesse enhancementOnly 14 pages are availabe for public view
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Abstract
This thesis aims to study the development of coupled cavities ring laser in sensing ap-plications using different technologies. For this purpose, a novel architecture of cou-pled cavities has been proposed based on dual coupler ring resonator coupled to a ring laser cavity. The novel configuration was studied in passive mode of operation (with-out gain medium) and compared to the conventional configurations of coupled cavi-ties. The effect of introducing a gain medium to compensate the cavity losses was also studied for single and coupled cavities. The active cavity was then used to increase the sensitivity of spectroscopic gas sensing using incoherent broadband cavity en-hanced spectroscopy (IBCEAS) technique. The operation of the ring laser with the proposed configuration as sensor was then studied and demonstrated as gyroscopic sensor.
The thesis is divided into six chapters as listed below:
Chapter 1:
This chapter gives a brief introduction of the motivation, objectives, major contribu-tions and organization of the thesis.
Chapter 2:
This chapter presents a review of the main concepts related to coupled cavities ring resonators and external cavities lasers. In the beginning, we discuss the different con-cepts related to ring resonators, the different configurations of coupled cavities ring resonators and their applications.
Chapter 3:
This chapter introduces a novel coupled cavities ring resonators configuration which consists of dual coupler ring resonator coupled to the main cavity. Firstly, we discuss the response of the proposed configuration giving analytical expressions for its differ-ent parameters. Secondly, we compare the analytical results with numerical simulations to get the percentage error in the different formulas under different conditions. Thirdly, we compare the proposed configuration with other ring resonators configura-tions.
Chapter 4:
This chapter proposes a novel technique to characterize resonators with long length and small free spectral range (FSR) using radio frequency (RF) beating signal. This method is used to characterize fiber cavities. Then, the usage of gain medium inside the cavity is discussed to compensate cavity losses. Active ring resonators were meas-ured for both single and coupled cavities showing a great enhancement in cavity full width half maximum (FWHM). A model was proposed to simulate the effect of gain medium in this active optical filter. Finally, the active optical resonator was used to increase the sensitivity of incoherent broadband cavity enhanced spectroscopy for gas sensing applications.
Chapter 5:
This chapter studies the usage of the proposed configuration in laser cavities for non-reciprocal sensing applications. Three major effects were discussed: increase in RF beating signal power, dynamic range extension and enhancement in scale factor using vernier effect. A simple model was suggested to study the effect of the coupled cavity in the laser system. The concept was demonstrated experimentally for gyroscopic ap-plications.
Chapter 6:
This chapter gives the conclusion of this thesis and introduces several recommenda-tions and suggestions for the future work.