**Credit Hours: **3 Hours

**Prerequisites:** OSE 3052

**Course Overview**

This course is an introduction to the principles of operation and design of lasers. The concept of the photon is first introduced and processes of interaction of light with matter for the absorption of light (and its application to detectors) and the generation of light via spontaneous and stimulated emission. Atomic transitions leading to fluorescence are introduced. Light amplification by stimulated emission of radiation is introduced as the basis of optical amplifiers. Optical resonators are described as a means for optical feedback. The laser is then introduced as an optical oscillator and compared to radio and microwave oscillators. Basic characteristics and types of lasers including continuous wave and pulsed lasers are discussed. Engineering applications, including devices such as scanners, CD players, and printers; industrial applications such as cutting and welding; and medical applications such as surgery, therapy, and diagnostics by means of imaging and spectroscopy. The course ends with a brief introduction to nonlinear optics and its use for wavelength conversion (second-harmonic generation and frequency up- and down-conversion).

Topics to be Covered:

- Ray Tracing in an Optical System: Ray Matrices, Applications to optical cavities, Stability diagrams;
- Gaussian Beams: TEM00 modes; Physical description of Gaussian beams, (Amplitude, radial and longitudinal phase); higher order modes; ABCD Law for Gaussian beams,
- Optical Cavities: Gaussian beams in stable resonators; ABCD law applied to optical cavities; mode volume.
- Resonant Optical Cavities: General concepts; Cavity Q and Finesse; Photon lifetime; Cavities with gain.
- Atomic Radiation: Simple Harmonic Oscillator; Einstein A&B coefficient approach; Line shape functions; Amplification by an atomic system.
- Laser Oscillation and Amplification: Threshold conditions; Laser oscillation/amplification in homogeneous broadened medium; Gain saturation in H.B. medium.
- General Characteristics of Lasers; Two three, four level lasers; C.W. Lasers( ring, standing wave, optimum output coupling problem);
*Laser Dynamics (solving rate equations)* sub-threshold; c.w. at threshold; small signal a.c. modulation; relaxation oscillations; gain switching; Q switching.
- Semiconductor Lasers (Time Permitting)

**Learning Outcomes:**

Upon completing this course, the students will:

- Understand the concept of the photon and describe the photon.
- Explain the basic phenomena involved in interaction of light with matter: absorption, emission, fluorescence.
- Explain the concept of optical amplification by stimulated emission of radiation.
- Describe how light is confined in an optical resonator and the resonator modes.
- Design a simple laser cavity.
- Describe the operational principles of the laser.
- Estimate the output power of a laser based on properties of the gain medium and cavity.
- Interrelate laser power, pulse energy, and irradiance.
- Distinguish the different types of lasers and their basic specifications, and be able to select the type of laser for a given set of specifications of wavelength, power, and pulse width.
- State some of the main applications of lasers.
- Explain how to produce/extend the wavelength range of a laser using nonlinear optics
- Relate an integrated view of science and engineering by explaining the fundamental analogies between electronic, electromagnetic, and optical oscillators (lasers).