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ELEC_ENG 409: Semiconductor Lasers

CATALOG DESCRIPTION: Basic concepts of lasers; laser applications; gas and liquid lasers; solid-state lasers; semiconductor lasers; materials and devices; rate equations; laser gain and saturation; modulation and light pulse generation; advanced technology for semiconductor laser fabrications and integration; industrial and medical applications of lasers.

REQUIRED TEXTS: S. L. Chuang, Physics of Optoelectronic Devices , Wiley, 1995.

REFERENCE TEXTS:

• G. P. Agrawal, N. K. Dutta, Semiconductor Lasers , Van Nostrand Reinhold, 1993.
• M. Razeghi, MOCVD Challenge , Vol. 1, Adam Hilger, 1989, Vol. 2, Institute of Physics Publishing, 1995.
• K. Iga, Fundamentals of Laser Optics , Plenum Press, 1994.
• M. Razeghi, Fundamentals of Solid State Engineering , 2 nd ed., Springer, 2006.

COURSE INSTRUCTOR: Prof. Hooman Mohseni

COURSE DIRECTOR: Prof. Manijeh Razeghi

COURSE GOALS: The course is designed to provide an understanding of the basic principles of operation of the modern diode semiconductor lasers. The course provides the opportunity for students to extend their background in semiconductor physics and theory and undertake advanced study and research in the variety of different branches of semiconductor optoelectronics. Content covers physics and operational characteristics of the double-heterostructure and quantum well lasers, dielectric waveguides, and issues of electrical and optical confinement in devices. For students who are looking toward industry positions after graduation this course is to widen background in optoelectronics. For students who plan on Ph.D. studies, it provides an excellent opportunity to prepare themselves for advanced experimental and theoretical research in semiconductor lasers and related fields.

PRE-REQUISITES BY COURSES: ELEC_ENG 403 or ELEC_ENG 405 or any course on semiconductors or consent of instructor.

DETAILED COURSE TOPICS:

Week 1: Basic concepts of lasers: gas lasers, liquid and solid state lasers. Non-equilibrium states in semiconductors. Transparency condition. Gain and stimulated emission. Absorption and gain in quantum wells.

Week 2: Momentum matrix elements of III-V bulk and quantum well semiconductors.

Week 3: Recombination mechanisms in semiconductors. Radiative recombination. Defect and surface recombination. Auger recombination. Recombination rates in quantum wells.

Week 4: Optical waveguides. Dielectric slab and rectangular waveguides. TE- and TM-modes. Longitudinal, transverse and lateral modes.

Week 5: Optical confinement factor. Refractive index in III-V materials. Wave guidance in lossy and gain medium. Threshold condition.

Week 6: Semiconductor lasers. Materials for semiconductor lasers. Double heterostructure lasers.

Week 7: Output power and differential quantum efficiency. Leakage current. Threshold current. Quantum well lasers. Peak gain and threshold current.

Week 8: Direct modulation of semiconductor lasers. Linear gain theory. Nonlinear gain saturation. High-speed modulation response.

Week 9: Power spectrum and semiconductor laser spectral linewidth. Linewidth enhancement factor.

Week 10: Quantum cascade lasers. Surface-emitting lasers. Quantum dot lasers. Future trends in semiconductor diode lasers.

GRADES:

• Homeworks – 25%
• Exams – 50%
• Projects – 25%

COURSE OBJECTIVES: When a student completes this course, s/he will understand the basic physics of optical processes in semiconductors: electronic structure, selection rules for interband and intersubband transitions, recombination, spontaneous and stimulated emission; be able to calculate the electrical and optical confinement in laser structures; understand the physics behind the semiconductor laser operation, basic parameters of laser performance and their limiting factors; be able to calculate laser characteristics.

ABET: 50 % Science, 50 % Engineering