Questions and Answers
What is the primary principle behind the operation of a semiconductor laser?
Which materials are used in the construction of a semiconductor laser?
What ensures population inversion in the p-n junction of a semiconductor laser?
What is the typical high current density required for continuous stimulated emission in a semiconductor laser?
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Which component of the semiconductor laser is responsible for reflecting the laser beam partially?
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What role do the rough surfaces play in the construction of a semiconductor laser?
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What is another name for the semiconductor laser due to its operation principle?
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How is the output wavelength of the laser determined?
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Study Notes
Principle of Semiconductor Laser
- Emission of recombination energy occurs in the form of light.
Construction of Semiconductor Laser
- Utilizes Gallium Arsenide (GaAs) and p-GaAs materials.
- Standard dimensions of the laser are 1 mm × 1 mm × 1 mm.
- Ohmic contacts are formed on the upper and bottom surfaces of the p-n junction.
- Front and back surfaces act as resonators for the laser.
- End faces are parallel and polished to ensure optimal light reflection.
- One end is fully reflecting, while the opposite end is partially reflecting to allow some light exit.
- Remaining two surfaces are roughened to prevent light leakage.
- Diode operates with forward bias near the band gap voltage of the material.
- Both p-type and n-type layers are heavily doped to enhance performance.
Working Mechanism
- Heavy doping in p-type and n-type regions creates population inversion at the depletion region of the diode.
- Forward-bias voltage applied is equivalent to the energy gap voltage (V = Eg/e).
- Recombination of electrons and holes occurs, leading to light emission.
- A high current density, around 20 kA/cm², is required to maintain continuous stimulated emission.
- Increased current density injects more electrons into the n-region and more holes into the p-region, facilitating continuous light emission.
- Referred to as an injection laser due to its charge carrier dynamics.
- Laser output is emitted from the p-n junction through the partially reflecting surface.
- Output wavelength formula is expressed as: ( λ = \frac{hc}{Eg} ), where ( h ) is Planck's constant and ( c ) is the speed of light.
Applications of Semiconductor Lasers
- Utilized in research and investigation fields.
- Employed for high-intensity light generation.
- Used in micro welding processes.
- Capable of direct extraction and laser applications in various industries.
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Description
This quiz covers the principles and construction aspects of semiconductor lasers. Key topics include the emission of light from recombination energy and detailed structural features such as the use of Gallium Arsenide. Test your understanding of the working mechanism and components that enhance laser performance.
