الفهرس 
CHAPTER I: GENERAL INTRODUCIONOnly 14 pages are availabe for public view
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Abstract
The successful remote operation of equipment for maintenance and diagnostics tasks in
the future International Thermonuclear Experimental Reactor (ITER) requires the development
of transmission links that can withstand high total dose, ranging from 1 to 100 MGy, depending
on the particular working conditions. Therefore, the feasibility of applying photonic technology
in such intense radiation fields and up to very high particles fluences needs to be assessed.
Although a considerable amount of radiation effects studies of laboratory experiments on
individual devices exposed to a variety of radiation conditions are reported in literature, only a
few theoretical models are available to describe the behaviors of the irradiated optoelectronics
devices. Also, there is a scarcity of analysis of the optical, the electrical properties and the
communication parameters of the devices working under the high temperature irradiation. The
proposed mathematical models in this thesis provide a clearer understanding and a deeper
analysis of the laboratory results and also the ability to extrapolate and predict the most accurate
results for changing of the performance characteristics of irradiated optoelectronic devices.
The Vertical Cavity Surface-Emitting Laser (VCSEL) is considered one of the most
important devices for enabling ultra parallel information transmission in lightwave and
computer systems. Neutron fluences were chosen in such a way that one gets estimates of the
behavior especially in space environments and nuclear engineering. Laser Diodes show a
reduction of light output power and also a shift of threshold current after irradiation. The thesis
has proposed the study of the transmission bit rates and products of optical laser diode sources
such as VCSEL under thermal irradiated environments. We have taken into account the
performance characteristics of these devices such as the harmonic response transfer function, the
resonance frequency, 3-dB bandwidth, damping frequency and the pulse rise time. Both the
ambient temperature and irradiation dose as well as the spectral wavelength possess serve
reduction effects on the transmission characteristics (dispersion and bandwidth) and
consequently the transmitted bit rates and products.
In addition, we have investigated the performance of PIN photodiodes employed in high
temperature-irradiated environment. Nonlinear relations are correlated to investigate the currentvoltage
and capacitance-voltage dependences of the silicon PIN photodiodes, where thermal and
gamma irradiation effects are considered over the practical ranges of interest. Thermal and
irradiation effects are modeled over the practical ranges of interest. Both the ambient
temperature and irradiation dose as well as the spectral power of incident light possess several
effects on the electro-optical PIN photodiode characteristics (dark current, photocurrent,
absorption coefficient, responsivity, quantum efficiency, rise time, bandwidth and directivity)ABSTRACT
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and consequently signal to noise ratio (SNR) and bit error rate (BER) for analog and digital
optical link systems. The results of each of SNR and BER show that, InGaAs PIN photodiodes
more radiation hardness than Si PIN photodiode.
Moreover, we have also taken into account the radiation dependent characteristics of the
avalanche photodiodes (APDs). The study has presented the main irradiation effects, i.e., the
multiplication gain, minority carrier life time, impact ionization, illumination and radiation
damage coefficient. By comparing protons and gamma radiation effects, we will applied the
model on the two different silicon APD structures. The fluence effects of 51 MeV proton
irradiation on the photosensitivity and SNR are also investigated. Also, we have taken into
account the effects of excess noise on the device performance and then to decrease the bit error
rated that has a bad effect on the operating efficiency. The results demonstrate that the model
can accurately calculate the internal parameters of the APDs and produce data that can be
directly compared with measurements.
Finally, we have taken into account the integrated device that is composed of a
Hetrojunction Phototransistor (HPT) and a Laser Diode (LD) or Light Emitting Diode (LED).
The expressions describing the transient response of the output, the rise time, and the output
derivative are derived. The results show that the transient response of the two types of the
device strongly depends on the optical feedback inside the device and it is found that the device
works in two different modes. They are amplification for small optical feedback coefficient and
switching for high optical feedback coefficient. The rise times in both types of the device are
calculated in order to calculate the transmission bit rates depending on non return to zero (NRZ)
and return to zero (RZ) coding formats in both modes. By increasing the optical feedback, the
rise time in the amplification mode is increased along with an increasing output, while that in
the switching mode can be reduced effectively with a saturated output.