Lasers and Photonics
How lasers work and how light is used in technology, developed as a full course in laser physics and photonics: the properties of laser light, photon rates, radiance and coherence, and the history from Einstein's 1917 prediction of stimulated emission through the maser, the ruby laser and low-loss optical fibres to chirped pulse amplification and attosecond pulses; absorption, spontaneous and stimulated emission, the Einstein coefficients and their link to dipole matrix elements, and why gain needs a population inversion in three- and four-level systems; homogeneous and Doppler line broadening, stimulated-emission cross sections, gain coefficients, saturation and spectral hole burning; optical resonators analysed with ray matrices and the stability condition, Gaussian and higher-order transverse modes, longitudinal modes, photon lifetime, finesse and Q; the threshold condition and the laser rate equations, gain clamping, switch-on spiking, relaxation oscillations, output coupling and slope efficiency; gas, solid-state, fibre and semiconductor lasers compared by pumping, quantum defect and wall-plug efficiency; Gaussian beam propagation and focusing with the complex beam parameter, beam quality and temporal coherence; Q-switching, mode-locking, the time–bandwidth limit, chirped pulse amplification and high-harmonic generation; optical fibres with numerical aperture, the V number and single-mode cutoff, attenuation, modal and chromatic dispersion and link budgets; nonlinear optics with second-harmonic generation, phase matching and quasi-phase matching, the Kerr effect, self-phase modulation and solitons; light-emitting diodes, photodiodes and receiver noise, electro-optic modulators and silicon photonic ring resonators; and a capstone on optical communications, lidar, laser materials processing, medicine, quantum photonics and laser safety, with runnable Python examples throughout.
PHYS-460 Year 4 3 credits 12 lessons · 4 h 53 min ▶ Video lessons coming soon
Offered by HSM University · Physics
This is the Canadian version of this course. See the American version.
What you'll learn
- Explain what distinguishes laser light from ordinary light, estimate photon rates, radiance and coherence lengths, and outline the history of lasers and photonics.
- Derive Einstein's relations between the A and B coefficients, relate them to dipole matrix elements, and explain why gain requires a population inversion and at least three energy levels.
- Describe homogeneous and inhomogeneous line broadening, compute Doppler widths, cross sections and gain coefficients, and explain gain saturation and spectral hole burning.
- Use ABCD matrices and g parameters to test resonator stability, and compute mode sizes, free spectral ranges, photon lifetimes, finesse and Q.
- Derive the threshold condition and solve the laser rate equations for steady-state output, gain clamping, relaxation oscillations and slope efficiency.
- Compare gas, solid-state, fibre and semiconductor lasers by gain medium, pumping, quantum defect and wall-plug efficiency, and choose a laser for an application.
- Propagate and focus Gaussian beams with the complex beam parameter, use \(M^2\) to describe real beams, and relate fringe visibility and coherence length to the spectrum.
- Explain Q-switching and mode-locking, apply the time–bandwidth limit, and describe chirped pulse amplification and high-harmonic generation of attosecond pulses.
- Compute the numerical aperture, V number and cutoff of optical fibres, and analyse attenuation, modal and chromatic dispersion and link power budgets.
- Explain second-order and third-order nonlinear optics, compute second-harmonic efficiency and coherence length, and describe phase matching, the Kerr effect and optical solitons.
- Analyse LEDs, photodiodes, receiver noise, electro-optic modulators and ring resonators, and explain the role of integrated photonics.
- Apply the course to optical communications, lidar, laser processing, medicine and quantum photonics, and assess laser hazards using exposure limits, laser classes and hazard distances.
Course content
12 lessons · 4 h 53 min total · final exam
- 1 Why lasers and photonics: light as a technology 25 min · quiz
- 2 Light–matter interaction: absorption, emission and Einstein coefficients 25 min · quiz
- 3 Line broadening, gain and population inversion 26 min · quiz
- 4 Optical resonators: modes, stability and the Fabry–Pérot cavity 24 min · quiz
- 5 Laser principles: threshold, rate equations and output power 24 min · quiz
- 6 Laser types: gas, solid-state, fibre and semiconductor lasers 24 min · quiz
- 7 Gaussian beams, coherence and beam quality 23 min · quiz
- 8 Pulsed lasers: Q-switching, mode-locking and ultrafast optics 25 min · quiz
- 9 Optical fibres: guidance, modes, attenuation and dispersion 23 min · quiz
- 10 Nonlinear optics: harmonic generation, phase matching and the Kerr effect 23 min · quiz
- 11 Photonic devices: LEDs, photodetectors, modulators and integrated photonics 23 min · quiz
- 12 Capstone: photonics at work — telecommunications, lidar, laser manufacturing, medicine and quantum photonics 28 min · quiz
- E Final exam 20 questions
Requirements
Recommended background. You can start any course at any time.
Description
How lasers work and how light is used in technology, developed as a full course in laser physics and photonics: the properties of laser light, photon rates, radiance and coherence, and the history from Einstein's 1917 prediction of stimulated emission through the maser, the ruby laser and low-loss optical fibres to chirped pulse amplification and attosecond pulses; absorption, spontaneous and stimulated emission, the Einstein coefficients and their link to dipole matrix elements, and why gain needs a population inversion in three- and four-level systems; homogeneous and Doppler line broadening, stimulated-emission cross sections, gain coefficients, saturation and spectral hole burning; optical resonators analysed with ray matrices and the stability condition, Gaussian and higher-order transverse modes, longitudinal modes, photon lifetime, finesse and Q; the threshold condition and the laser rate equations, gain clamping, switch-on spiking, relaxation oscillations, output coupling and slope efficiency; gas, solid-state, fibre and semiconductor lasers compared by pumping, quantum defect and wall-plug efficiency; Gaussian beam propagation and focusing with the complex beam parameter, beam quality and temporal coherence; Q-switching, mode-locking, the time–bandwidth limit, chirped pulse amplification and high-harmonic generation; optical fibres with numerical aperture, the V number and single-mode cutoff, attenuation, modal and chromatic dispersion and link budgets; nonlinear optics with second-harmonic generation, phase matching and quasi-phase matching, the Kerr effect, self-phase modulation and solitons; light-emitting diodes, photodiodes and receiver noise, electro-optic modulators and silicon photonic ring resonators; and a capstone on optical communications, lidar, laser materials processing, medicine, quantum photonics and laser safety, with runnable Python examples throughout.
Part of the Science stream, typically taken in year 4.