High performance, low cost and compact size modules are required for the modern communication systems. To design such models, we should depend on the modern technology-based materials and new techniques such as Defected Ground Structure (DGS), Electromagnetic Band Gap (EBG), Partial substrate Removal (PSR), and Photonic Band Gap (PBG). The Design of antennas with defected ground structures will explore additional resonant frequencies and the improvement in bandwidth is also possible. In this work, design and analysis of CPW-fed monopole antenna for UWB applications are proposed with defected ground structure. Later, a compact L-shaped monopole is designed and substrate removal technique is applied to enhance the bandwidth of the antenna. A fractal antenna with a swastika-shaped structure is designed and a substrate removal technique is applied to enhance the gain of the antenna. Finally, a circular half ring monopole antenna, Stub loaded circular-shaped antenna and a circular notch band antenna a circular notch band antenna a circular notch band antenna a circular notch band antenna a circular notch band antenna with DGS are proposed for ultra wide band applications.
Recently organic semiconductors have obtained considerable interest in the fields of electronic and photonic devices due to a wide range of applications and low cost. This work describes fabrication and investigations of organic semiconductor devices such as humidity, light and temperature sensors based on copper phthalocyanine (CuPc). Temperature dependent properties of organic-inorganic (Ag/CuPc/GaAs/Ag) heterojunctions were investigated in a wide temperature range of 82 to 350 K. The fabricated junctions could be used as photo-electric sensors for the NIR-UV spectral region. A photoelectric displacement transducer, organic phototransistor based on CuPc, and photo capacitive sensor based on poly-N-epoxypropylcarbazole complexes were fabricated and investigated as well. The concept of multi-functional sensors using organic semiconductors is discussed. Properties of CuPc films deposited at high gravity conditions from 50g to -50g by centrifugation were investigated.
With the rapid and ongoing developments in telecommunication and electronic warfare technology, faster and more flexible systems are in demand. Wideband signal processing is thus needed to implement such systems. Microwave photonics has been introduced as a tool for achieving such ultra - broadband signal processing. Instantaneous Frequency Measurement (IFM) receivers play an important role in electronic warfare. They have been developed as a means of obtaining a rapid indication of the presence of a threat and to roughly identify the frequency of the threat signals. They also have the advantages of low-cost, compactness and moderate to good sorting capability in an interference-free environment. The main limitation of the traditional IFM RF receivers is the constrained bandwidth. Microwave Photonic IFMs have been considered, but the main disadvantages of photonic realization of the recent IFM receiver is cost. This work proposes and demonstrates a low - cost photonic IFM receiver with a broad frequency measurement range. The proposed methods are based on the use of photonic mixing to down-convert the RF modulated optical signals to DC.
A hybrid silicon laser is a semiconductor laser fabricated from both silicon and group III-V semiconductor materials. The hybrid silicon laser was developed to address the lack of a silicon laser to enable fabrication of low-cost, mass-producible silicon optical devices. The hybrid approach takes advantage of the light-emitting properties of III-V semiconductor materials combined with the process maturity of silicon to fabricate electrically driven lasers on a silicon wafer that can be integrated with other silicon photonic devices. This book demonstrates the silicon evanescent laser, amplifier, modulator, photo detector and pre amplified photo detector individually and how these individual photonic components can be integrated together to form an optoelectronic device. A device that can make tera scale computing a reality.
Thin-film silicon solar cell is a promising technology for solar energy due to their low-cost large-scale manufacturability, but one of the major challenges is to absorb light at infrared wavelengths where the absorption length is much larger than the active layer thickness. This book overviews the state-of-the-art light trapping technology for efficiency improvement in thin-film Si solar cells. we propose an all-dielectric, textured photonic crystal (TPC) as an effective light trapping scheme, which integrates dielectric gratings and a distributed Bragg reflector (DBR) in the backside of thin film silicon. We understand the operation principles for this design by using photonic band theories and electromagnetic wave simulations. We also developed a self-assembled method to fabricate the proposed photonic structures. Finally, we explored the fundamental performance limits for thin-lm Si solar cells.
Providing insights into an advanced microscopy technique for polymer-based nanofabrication, this book covers all aspects of the direct laser writing, interpretations in detail of the concept of low one-photon absorption microscopy, as well as single-emitter/photonic devices coupling problems. Starting with the theory of focusing electromagnetic wave, the book goes on to treat various experimentally working conditions, i.e. medium with the mismatched refractive index and absorption, for calculating the intensity distribution at the focusing region. Experimental demonstrations show how a ultra low absorption property opens up a new trend for cost-effective 3D imaging and nanofabrication.
The Radio-over-Fiber (RoF) links play an important role in systems where mm-wave (60GHz) signals need to be distributed over many 100's of meters. In 60GHz RoF systems, cost of modulating a laser is a problem. A potentially low cost solution is the use of mm-wave pulse repetition frequencies mode-locked lasers (MLLs). In this book, a novel concept of injection-locking these MLL to implement mm-wave phase shift is introduced. Both magnitude and phase of the modulation response are measured using VNA and a "plateau" is observed in magnitude response which corresponds to the locking range of the system. The MLL phase shifter operation makes them an ideal candidate for mm-wave RoF phased array antenna and advanced antenna beam steering systems. The wireless injection locking of MLLs is also presented which uses modular integration of a MLL and a planar antenna. Then, a novel Photonic Active Integrated Antenna approach is introduced to further improve the integration, where a MLL is hybridly integrated with a planar antenna to perform wireless injection-locking. Finally, a novel self oscillating mixer behavior of the MLL is studied under both homodyne and heterodyne configurations.