Coupled Asymmetric Quantum Dot (CAD) Laser
Final rept. 1 Aug 2001-31 Dec 2003
STANFORD UNIV CA DEPT OF ELECTRICAL ENGINEERING
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Semiconductor solid state lasers based on conduction valence band recombination are now commonplace for low power red emission, and are available commercially at nearly continuous wavelengths throughout the near UV and near IR communications bands. Furthermore, new lasers and broadband spontaneous emission sources are available through a wide wavelength range, including 3-8 micron based on both conduction-valence band and intersubband transitions, and up to 7O micron using cascaded intersubband transitions. However, competing processes make the design of these semiconductor lasers extremely difficult when extended to the very long, 3OO micron wavelength regime corresponding to low terahertz frequencies. In this program, we have developed THz laser designs based on the intersublevel transitions in self assembled quantum dots QDs, where the lasing occurs through discrete conduction states. In an early implementation, two QDs are coupled to make a coupled asymmetric quantum dot CAD laser similar to the quantum cascade laser but offering improved benefits. Unfortunately, current technological limits impede the fabrication of this device. In another scheme, an ensemble of noncoupled QDs is selectively placed in a high quality cavity, called a microdisk, which is resonant with an intersublevel QD transition. In this program, we have demonstrated the initial fabrication of this structure.
- Lasers and Masers
- Solid State Physics