Mohammad Soroosh

Circuit modeling of separate absorption, charge and multiplication avalanche photodiode (SACM-APD)

We present a circuit model for separate absorption, charge and multiplication avalanche photodiode (SACM-APD). It is based on the carrier rate equations in the different regions of the device. Using the model we obtain the photocurrent, quantum efficiency, and dark current. As examples, GaAs and InGaAs/InAlAs SACM-APDs are simulated. There is a good correspondence between the simulation and experimental results.

A 4-Channel Demultiplexer Based on 2D Photonic Crystal Using Line Defect Resonant Cavity

ABSTRACT In this paper, a 4-channel demultiplexer based on 2D photonic crystal using line defect resonant cavity was proposed. The structure consists of one straight input and four vertical output waveguides with L3 cavities. The average quality factor is 4107.37, the crosstalk mean value is −27.33 db and the average transmission efficiency is 93.45%. Minimum pass band is 0.4 nm and channel spacing is around 2 nm. Cross section of the proposed structure is 360 so that the proposed multiplexer shows significant characteristics used in optical integrated circuits.

All-angle self-collimation in two-dimensional square array photonic crystals based on index contrast tailoring

Abstract. A comprehensive study has been performed to achieve all-angle self-collimation in basic two-dimen-sionalsquarearrayphotoniccrystalswithcylindricalscatterers.Basedonplanewaveexpansionandfinitediffer-ence time domain analysis for both rod- and hole-type structures, we report on all-angle self-collimation (SC) inthefirstbandofthestructure,whichresultsinlosssuppressionduetoout-of-planescatterings.Alowerthresholdfor index contrast has been obtained to achieve all-angle SC, which offers more design flexibility regardingstructural parameters. Furthermore, it has been shown that a minimum and maximum coupling efficiencyenhancement of ∼40% and 80% can be achieved for the proposed structure, respectively, by introducing arow of scatterers with proper radius at the input and the output air/photonic crystal interfaces.

Equivalent circuit model of noise for a separate absorption and multiplication avalanche photodiode (SAM-APD)

In this paper, we present a circuit model of noise for separate absorption, and multiplication avalanche photodiode (SAM-APD). Also a circuit model of SAM-APD is presented. It is based on the carrier rate equations in different region of device. As two examples, a GaAs and an InGaAs/InAlAs SAM-APD are simulated.

Low Loss and High-Quality Factor Optical Filter Using Photonic Crystal-Based Resonant Cavity

Abstract Transmission efficiency and quality factor are two of the most crucial characteristics in designing optical band pass filters. In this paper, we proposed a novel structure for realizing an optical filter. For the wavelength selecting part of the filter, we employed a V-shaped resonant cavity. The obtained filter has a resonant mode at 1313 nm with transmission efficiency and quality factor as much as 97 % and 3548, respectively.

A New Proposal for Ultra-Compact Polarization Independent Power Splitter Based on Photonic Crystal Structures

Abstract Polarization dependency imposes great limitations for application of optical device in optical networks and systems. In this paper, we are going to design and propose a 1*2 all optical polarization independent power splitter based on photonic crystal structures. For designing such a device we should employ a fundamental photonic crystal structure which has joint photonic band gap. The obtained results show that at 1,560 nm wavelength the final structure has transmission efficiency equal to 45 % for outputs in both TE and TM modes.

Design of highly efficient polarization beam splitter based on self-collimation on Si platform

Abstract A highly efficient polarization beam splitter based on self-collimation phenomenon in 2D square array of air holes in Si background is presented. For the presented structural parameters, a broad bandwidth of Δω/ωc = 1.3% for the incidence angle of |θin| < 80° is obtained. Here, a maximum deviation angle of |θp|max < 5° from ideal self-collimation is considered. The extinction ratios for TE and TM polarizations exceed 70 and 12 dB, respectively, in the whole frequency range through applying optimized anti-reflections at input and output ports. Structural simplicity and its compatibility with existing fabrication technologies along with the flexibility of the design to match for desired central frequency in IR range using scalability rule of Maxwell equations are outstanding features of the design.

A simple empirical model for calculating gain and excess noise in GaAs/AlξGa1-ξAs APDs (0.3≤ξ≤0.6)

In this paper, we present a simple empirical model for calculating gain and excess noise in heterojunction GaAs/AlξGa1-ξAs APDs (0.3≤ξ≤0.6), without going through the relatively complicated and time consuming Monte Carlo simulation, commonly used for such devices. In this model, we present a set of empirical formula which can predict a distribution function for ionization path length for a given electric field throughout multiplication region. To determine the optimized values of the adjustable parameters used in our empirical model, we train a back-propagation neural network. The results are in excellent agreement with those obtained by the random path length (RPL) technique.

Transient and frequency analysis of PIN avalanche photodetector using circuit model

This paper tries to characterize the PIN and avalanche photodiode (APD) in time and frequency domain using the circuit simulation in Spice. For this reason a circuit model of PIN avalanche diodes based on carrier rate equations has been considered. This model is able to pretend dc, ac, and transient response of diode. We contemplate the effects of variation in bias voltage and optical power on frequency and transient response

Static Quasi 3D Thermal Simulation of Ion Implanted Vertical Cavity Surface Emitting Lasers

In this paper, we simulate static thermal behavior of a gain guided VCSEL by solving quasi 3D heat equation. Several heat sources such as Joule heating, reabsorption of spontaneous emission and nonradiative recombination in different vertical positions of the device are considered. We use inhomogeneous thermal conductivities and see reduction of temperature in whole device than the case of homogenous. Moreover, by increasing current spreading, thermal lensing increases. However, increasing the aperture radius causes broadening of profile and lowering of temperature peak. We also found that Joule heating of p-DBR has critical role in temperature distribution. We also analyze the effect of top DBR period numbers on threshold current and active layer temperature peak.