Introduction to Laser

By Prof. M. R. Shenoy   |   IIT Delhi
Learners enrolled: 1450
This course introduces LASER to senior undergraduate students, as well as first year postgraduate students. The objective is to provide a detailed account of the basic physics, including resonator physics, and the principle of operation of Lasers. Issues relevant to the design and output characteristics of the Lasers, and some specific laser systems would also be discussed. The course is ‘applied’ in nature, and could be taken by B.E/B.Tech IIIrd/ IVth Year, M.Sc IInd/ M.Tech. I Year. Working engineers/scientists/teachers, who did not have exposure to the subject earlier, would also find it very useful, if interested. The course would require a regular and serious study schedule on the part of the students (to understand the subject and do well).

INTENDED AUDIENCE : IIIrd, IVth year B.Tech / M.Sc (Physics/ Electronics/ Electronic Sciences) students, and also M.Tech Ist Sem students, who had no previous exposure to Lasers in any course. PLUS Engineers working/ dealing with Lasers
PREREQUISITES : Basic undergraduate-level knowledge of Electromagnetics, Optics, and Atomic Physics/Modern Physics would be required.
INDUSTRIES SUPPORT : Companies and R&D Laboratories working on Laser Applications, Optoelectronic and Optical Communication are expected to value this course.
Course Status : Completed
Course Type : Elective
Duration : 12 weeks
Category :
  • Physics
Credit Points : 3
Level : Undergraduate/Postgraduate
Start Date : 24 Jan 2022
End Date : 15 Apr 2022
Enrollment Ends : 07 Feb 2022
Exam Date : 23 Apr 2022 IST

Note: This exam date is subjected to change based on seat availability. You can check final exam date on your hall ticket.

Page Visits

Course layout

Week 1:PART – I: Interaction of Radiation with Matter
General Introduction, Spontaneous and stimulated emissions, the Einstein coefficients
Week 2:Line shape function, Line-broadening mechanisms: Homogeneous and inhomogeneous broadening, natural-, Doppler- and collision broadening.
Week 3: PART – II: Scheme of Light Amplification
Rates of stimulated emission and absorption, condition for amplification by stimulated emission, the meta-stable state and laser action.
Week 4:3-level and 4-level pumping schemes. Laser Rate Equations: Two-, three- and four-level laser systems, condition for population inversion, gain saturation;
Week 5:Laser amplifiers, gain and bandwidth; Rare earth doped fiber amplifiers.
Week 6:PART – III:
Optical Resonators Plane mirror resonator: resonance frequencies, cavity loss, cavity lifetime and Q-factor;
Week 7: Spherical mirror resonators: Ray paths in the resonator, stable and unstable resonators,resonator stability condition
Week 8:Transverse modes of laser resonators. Hermite-Gauss modes of a spherical mirror resonator. Gaussian beams in laser resonators.
Week 9:PART – IV:
The Laser Laser Oscillations, Optical feedback, threshold condition, variation of laser power near threshold, optimum output coupling,
Week 10:Characteristics of the laser output, oscillation frequency, Mode selection, single-frequency lasers; Methods of pulsing lasers, Q-switching and mode-locking.
Week 11: PART – V: Some Laser Systems: Ruby, He-Ne, Nd:YAG, Fiber lasers
Week 12:Tunable lasers: The Ti Sapphire laser, Semiconductor lasers; Laser safety.

Books and references

1. B. E. A. Saleh and M. C. Teich, Fundamentals of Photonics, John Wiley & Sons, Inc., 2nd Ed. (2007), Ch.10, 13-15.
2. K. Thyagarajan and Ajoy Ghatak, Lasers: Fundamentals and Applications, Macmillan Publishers India Ltd., 2nd Ed. (2011), Ch.4, 5, 7, 10-13.
3. W. Koechner, Solid-State Laser Engineering, Springer, 6th Ed. (2006).
4. W. T. Silfvast, Laser Fundamentals, Cambridge Univ. Press, Cambridge, (1996).

Instructor bio

Prof. M. R. Shenoy

IIT Delhi
M. R. SHENOY received the M. Sc. in Physics in 1979 from Mysore University and the PhD in the field of Fiber and Integrated Optics from IIT Delhi in 1987. He joined the faculty of IIT Delhi in 1988, where he is currently Professor in the Department of Physics. Dr. Shenoy was a Visiting Scientist with the Department of Electrical and Electronic Engineering, University of Glasgow, Glasgow, U.K., in 1990 for 10 months, and on short- duration visits at the University of Nice Sophia Antipolis, Nice, France, in 1992, 1997, 2006 and 2008 for collaborative research on Integrated Optical Devices. He has authored/co- authored a number of research papers and book chapters, and has supervised a large number of student projects at the B.Tech, M.Sc. M.Tech and Ph.D. levels. He is a co-editor of the book Fiber Optics Through Experiments (Viva Publications, New Delhi, 1994, 2008). He has delivered a full video course of 46 lectures on Semiconductor Optoelectronics, facilitated by NPTEL, and freely available for download on YouTube. He has been involved in several Sponsored R&D projects on the design and development of guided-wave optical components and devices. His current research interests are in the area of Optoelectronics and Guided Wave Optical Components .

Course certificate

The course is free to enroll and learn from. But if you want a certificate, you have to register and write the proctored exam conducted by us in person at any of the designated exam centres.
The exam is optional for a fee of Rs 1000/- (Rupees one thousand only).
Date and Time of Exams: 23 April 2022 Morning session 9am to 12 noon; Afternoon Session 2pm to 5pm.
Registration url: Announcements will be made when the registration form is open for registrations.
The online registration form has to be filled and the certification exam fee needs to be paid. More details will be made available when the exam registration form is published. If there are any changes, it will be mentioned then.
Please check the form for more details on the cities where the exams will be held, the conditions you agree to when you fill the form etc.


Average assignment score = 25% of average of best 8 assignments out of the total 12 assignments given in the course.
Exam score = 75% of the proctored certification exam score out of 100

Final score = Average assignment score + Exam score

YOU WILL BE ELIGIBLE FOR A CERTIFICATE ONLY IF AVERAGE ASSIGNMENT SCORE >=10/25 AND EXAM SCORE >= 30/75. If one of the 2 criteria is not met, you will not get the certificate even if the Final score >= 40/100.

Certificate will have your name, photograph and the score in the final exam with the breakup.It will have the logos of NPTEL and IIT Madras .It will be e-verifiable at nptel.ac.in/noc.

Only the e-certificate will be made available. Hard copies will not be dispatched.

Once again, thanks for your interest in our online courses and certification. Happy learning.

- NPTEL team

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