Optimal efficiency calculations for 3C-SiC- and 6H-SiC-based intermediate band (IB) solar cells are presented. Using detailed balance methods, it is shown that the conversion efficiency of IB SiC-based solar cells is very sensitive to IB position, type of spectrum, and concentration of the incident light. Under a 1000 suns concentration and AM1.5 spectrum irradiation, a maximum efficiency of 55.9% is theoretically achieved for 3C-SiC with the IB located at 0.79 eV up to the valence band of the host material. Under the same conditions, a theoretical maximum efficiency of 49.7% is achieved with an IB located at 0.84 eV below the conduction band of the 6H-SiC. Based on the obtained theoretical results, the formation of an isolated IB in the appropriate position is demonstrated for Ni-doped 3C-SiC and Mn-doped 6H-SiC using the density function theory method which leads to an enhancement in the absorption coefficient in the ranges of the solar spectrum.
An integrated, compact and upgradeable bidirectional multiplexer/demultiplexer and Add-drop multiplexing based on
array of ring resonators is proposed. The proposed structure is realized using basic elements in optical integrated circuit
domain. We show that using the proposed block wavelength separation in dense wavelength division multiplexing
standard is possible. Also, the introduced basic block can be used to realize other elements in all-optical networks.
In optical applications including hybrid and integrated cases, there are some inherent phenomena such as dispersion, loss
and many others that must be critically removed for performance improvement. Among these dispersion is important for
light propagation and speed of transmission. Optical pulse broadening and chirping are main disadvantages of dispersion
in pulse propagation. Dispersion cancellation in these applications is crucial. Dispersion compensators are widely used
which are realized with different methods. In this paper a novel dispersion compensator and management system based
on electromagnetically induced transparency (EIT) is introduced. For realization of EIT phenomenon in this paper four
level atoms or quantum dots is used. In this analysis uniform distribution of these atoms is assumed. With application of
control fields the absorption and the index of refraction are controlled. So, with intensity of a control light the dispersion
factor is manipulated. For implementation of this idea ring resonator is considered. With application of control signal the
group delay, phase difference and dispersion are controlled. Easy integration of the proposed technique is an important
advantage of this method. Also, intensity of the control signal is main parameter for dispersion tuning. The proposed
technique is all-optical dispersion management system. Our calculations show delay time and dispersion value well over
nsec and 20 ps/km.nm respectively.
In this paper, an integrated all-optical high precision (well below 0.01 0C ) temperature sensor based on ring resonators
implemented by GaAs and InP is proposed. Analytical relations illustrating the effect of temperature on the intensity
transfer function and group delay are proposed. The index of refraction and length of the ring are changed due to applied
temperature. Based on the derived relations the effects of temperature on the output quantities are illustrated. The output
intensity and group delay can be used as suitable quantities for measuring of the applied temperature. In this analysis
matrix formulation of the light propagation through networks including ring resonator is used. The obtained analytical
relations are evaluated and simulated numerically. Based on our proposed method, it is shown that the proposed
technique supports ultra-high precision measurement. Our calculation and simulations show that based on the proposed
structure so sensitive sensor can be implemented easily using GaAs and InP as suitable material for manufacturing of ring resonators.
In this paper, we demonstrate a compact and integrated optical spectrum analyzer (OSA) based on ring resonator. In this
proposal thermo-optic, electro-optic, acousto-optic and nonlinear optic can be used as control signal to sweep and scan
the frequencies of the input signal. The applied control signal changes the index of refraction of ring resonator and
therefore the resonance frequency is changed and the output intensity in the reflected port is changed proportional to the
input signal contents. Also, the proposed idea can easily be integrated on optical chip. The presented design idea is
simple for realization using optical integrated circuits, has high accuracy (less than 4 pm) and compact. This new OSA is
suitable for the wavelength-division-multiplexing performance monitoring that requires high speed and high wavelength
measurement as well as other related applications.
In optical and optomechatronics applications including hybrid and integrated cases, there are some inherent phenomena such as dispersion, loss and many others that must be critically removed for performance improvement. Among the others, one of the most quantities is dispersion. Dispersion is important in most optical applications such as optical communications including all accessories and optical sensors. Optical pulse broadening and chirping are main disadvantages of dispersion effect. Dispersion cancellation in these applications is crucial. Dispersion compensators are widely spread with many methods for realization of that. In this paper a novel dispersion compensator and management system based on thermo optical effect is introduced. Thermo optical effect and the index of refraction changes due to temperature in ring resonator are used to manipulate dispersion quantity. Thermal source is generated in this case with application of electrical potential on metallic layer coated on ring resonator. Introduced idea is realized using ring resonators and results are presented.
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