Sample interview questions: What are some common techniques for achieving tunable laser output in the mid-infrared region?
Sample answer:
Common techniques for achieving tunable laser output in the mid-infrared region include the following:
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Optical parametric oscillation (OPO): OPO is a nonlinear process that utilizes a nonlinear crystal to generate new wavelengths by mixing the pump laser beam with a signal beam. By controlling the angle and temperature of the nonlinear crystal, the output wavelength can be tuned to the mid-infrared region.
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Optical parametric amplification (OPA): Similar to OPO, OPA also employs a nonlinear crystal to generate new wavelengths. However, instead of generating an oscillating output, OPA amplifies the signal beam at the desired wavelength. The output wavelength can be tuned by adjusting the crystal parameters.
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Difference frequency generation (DFG): DFG is a nonlinear process that involves mixing two input laser beams of different wavelengths in a nonlinear crystal to generate a new wavelength that corresponds to the difference in frequency between the two input beams. By adjusting the wavelengths of the input beams, the output wavelength can be tuned to the mid-infrared region.
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Quantum cascade lasers (QCLs): QCLs are semiconductor lasers that can be designed to emit in the mid-infrared region. They rely on intersubband transitions in quantum wells to achieve population inversion and lasing action. By engineering the quantum well structure, the emiss… Read full answer