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Showing posts from April, 2022

OPTICAL SWITCHING-SEED,Bipolar Controller Modulator

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 OPTICAL SWITCHING It is a process by which an optical signal can be routed to a desired communication path without converting them to electrical signal. There are two types of optical switches slow switch-used to route around a fault  in the optical fiber Fast Switch-uses Electro optic or magneto optic effect for switching There are 3 broad classification of  switches 1.Mechanical Method Mirrors and prisms are used to divert incoming optical signals to the required path. They can be controlled easily as they are simple in structure.Miniaturization and application in large scale communication equipment is difficult. 2. MEMS (Micro electro mechanical systems) The Mechanical components,sensors and actuators are fabricated on a silicon substrate.They are ideal for large scale switching.Their Power consumption is minimal.They need high processing capabilities for manufacturing. 3.Optical Wave guide Method These switches utilize the refractive index of substrates to guide opti...

TUNABLE THRESHOLD LOGIC GATE-SWITCHING SPEED AND ENERGY

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  The below figure is the circuit diagram of an MQW-HBT 3 input threshold gate Figure 1 MQW-HBT 3 input threshold gate To operate the gate,the light should be above the excitonic peak The Load resistor current is the superposition of currents in the MQW-HBT P-i-(MQW)-n diodes in parallel with HBTs modulate light of the same wavelength In the figure,a load resistance is used with a variable voltage supply. A Zener diode is connected in parallel with the MQW-HBT. It prevents damage due to accidental high voltages. For the light source,a tunable laser is used. When there is no light on the MQW-HBT, there is no current and no voltage drop across the load The function of the gate can be altered by changing the supply voltage For a  NOR function, 12v power supply and when none of the inputs is 1(illuminated),the output is 1 and if any of the input is 0,the output is 0 For a Inverse Carry Gate, 18v power supply  and when two or more inputs are 1,the output is 0,else output is 1 ...