Optical Sources

What are the materials used for fabrication of LED's ?

• GaAs

• GaAlAs

• Ge

• Si

In direct bandgap semiconductor, most energy is released in the form of

• Light

• Heat

• Light and heat

What are heterojunction structures ?

• Junctions formed by semiconductor with different band gap energies

• Junctions formed by semiconductor with same band gap energies

• Junctions formed by direct band gap semiconductor

• Junctions formed by indirect bandgap semiconductor

Full form of LASER

• Light Amplification by spontaneous emission of radiation

• Light Analysis by spontaneous emission of radiation

• Light Amplification by stimulated emission of radiation

• Light Analysis by stimulated emission of radiation

Which of the following is desired characteristics of an optical source ?

• Narrow spectral width

• Wide spectral width

• Coherent emission

• Incoherent emission

Which type of emissions are responsible for lasing action of a LASER ?

• Spontaneous emission

• Stimulated emission

• Both spontaneous and stimulated emissions

• Radiative recombination

Which type of recombination are responsible for light output of LED?

• Non-radiative recombination

• Radiative recombination

• Radiative and Non-radiative recombination

Which type of recombination are responsible for light output of LED?

• Non-radiative recombination

• Radiative recombination

• Radiative and Non-radiative recombination

Which type of recombination are responsible for light output of LED?

• Non-radiative recombination

• Radiative recombination

• Radiative and Non-radiative recombination

What is the full form of ELED

• Emission LED

• Edge- emitting LED

• Efficient LED