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BSc Physics with Theoretical Physics / Course details

Year of entry: 2021

Course unit details:
Lasers and Photonics

Unit code PHYS30611
Credit rating 10
Unit level Level 3
Teaching period(s) Semester 1
Offered by Department of Physics & Astronomy
Available as a free choice unit? No


Lasers and Photonics


Unit title Unit code Requirement type Description
Introduction to Photonics PHYS20612 Pre-Requisite Compulsory


This course follows on from PHYS20612, thereby providing a solid background for the physics and operation of different types of lasers and photonic principles, together with examples of their use in scientific research.  

Learning outcomes

This course unit detail provides the framework for delivery in 20/21 and may be subject to change due to any additional Covid-19 impact.  Please see Blackboard / course unit related emails for any further updates

On completion of the course, students will be able to:
1. Demonstrate how a laser operates, and how optical feedback is used to ensure lasing.
2. Explain line broadening and how this is of relevance to laser operation.
3. Demonstrate how the concepts of laser thresholds, gain and the oscillation conditions can be derived using rate equations.
4. Review multi-mode laser operation, including higher order cavity modes.
5. Describe the operation and output characteristics of a selection of laser sources.
6. Review applications of lasers and photonics in scientific research.


1. Basic laser physics: Einstein A and B coefficients; induced and spontaneous transitions; systems in thermal equilibrium; population inversion.

2. Homogeneous and inhomogeneous broadening: Doppler; natural; pressure; Gaussian and Lorentzian lineshapes and widths, the Voigt Profile.

3. Develop the processes that lead to lasing from a single atom – laser field interaction using density matrices, through to the solutions for many atoms in a gain medium.

4. Gain saturation: homogeneous and inhomogeneous; saturation intensity. 

5. Laser oscillation: oscillation conditions; threshold conditions; passive cavity frequencies.

6. 3 and 4 level lasers: power to maintain threshold, output coupling & optimization.

7. Multi-mode laser oscillation.

8. Laser cavities and modes: Gaussian modes; high order transverse modes; frequencies of oscillation; Laguerre-Gaussian modes, mode stability.
9. Examples of different laser systems: CW, pulsed, tunable.

10. Applications and examples of lasers & photonics used in research.

Assessment methods

Method Weight
Other 33%
Written exam 67%

Feedback methods

Feedback & exercises will be available through examples presented during the lectures together with answers available via Blackboard, and through working through the solution of selected examples in the lectures.

Recommended reading

Milloni, P.W. & Eberly, J.H. Lasers
Saleh, B.E.A., Teich, M.C. Fundamentals of Photonics (Wiley)
Siegman, A.E. Lasers (University Science Books)
Smith, F.G. & King, T.A. Optics and Photonics: An introduction (Manchester Physics)
Wilson, J. & Hawkes, J.F.B. Optoelectronics: An introduction (Prentice Hall)
Yariv, A. Introduction to Optical Electronics (Wiley)

Study hours

Scheduled activity hours
Assessment written exam 1.5
Lectures 24
Independent study hours
Independent study 74.5

Teaching staff

Staff member Role
Andrew Murray Unit coordinator

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