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Course Info | Class Notes | Evaluation / Check Marks | Labs | Class Schedule & Homework |

The nature of light itself as well as the atomic processes leading to light production, the mechanisms of incoherent light production, as well as the fundamentals of laser action will be examined. Incoherent sources of emission including blackbody radiators, gas discharges, and semiconductor sources will be studied and modeled and spectroscopic emissions analyzed. For an atomic system quantum mechanics will be used to model energy levels and transitions (hence predicting the emission spectrum). Most importantly, the basic mechanics of lasers will be covered including the quantum processes involved, concept of laser gain, excitation mechanisms, and optical resonators. Mathematical models of laser action, based on rate equations, will be developed allowing computation of thresholds (e.g. gain) and prediction of performance. The concept of laser gain and saturation will be examined, both in theory and in the lab. An intensive laboratory component allows students to explore course material in a practical hands-on manner.

In this course students will build their own laser using custom helium-neon plasma tubes with antireflective windows in place of the usual integral mirrors. External optics allow students to align the cavity as well as insert intra-cavity optics such as a variable loss used to measure the gain of the laser - in this case the output coupler is inside the kinematic mount with two adjustment screws visible. The beam is made visible in this photo by using a commercial fog machine. This photo is, of course, the cover photo of the text used in the course (Photo © 2004 John Wiley & Sons, publishers).

Prerequisites, etc.

• Prerequisites for the program (and hence this course) are a College Diploma in Engineering Technology or an undergraduate University Degree in Physics, Chemistry, or Engineering. A strong background in physics and optics is required as well as the ability to apply algebra and calculus to solve problems.
• This course is a prerequisite for PHTN9180 Laser Systems
• This course is equivalent to BATP9301 Laser Systems
• This course is offered as part of the post-graduate Advanced Lasers certificate

Evaluation ...

• Three midterm examinations, totalling 60%, as follows ...
Midterm #1 during week 6 (on Tuesday 2011/10/11) in class
One Hour, in class, worth 15%. (Chapters 1, 2, and 3)
Midterm #2 during week 10 (on Tuesday 2011/11/08) in class
One Hour, in class, worth 15%. (Chapter 4)
Final term test #3 during week 14 (on Thursday 2011/12/08) in class
Two hours, in class, worth 30%. It is not an "all encompassing" final exam (there is no "traditional" all-encompassing final exam in this course during exam period) but rather a demonstration of application of learned theory.


• Labs and assignments combined for a total of 40%

Check your marks here NOTE: these are UNOFFICIAL marks to be used only for the guidance of students as the term progresses. Official marks will appear on your transcript at the end of the term.

Course policies match the Standardized Policies and Procedures for CEE (dated January 2011). In summary:

• LATE assignments are worth ZERO. There is no "grace period" with a "per day" penalty. Late submissions (i.e. ANY not printed and ready when you enter the lab) receive a mark of zero. You will be DENIED access to the printer at the start of the lab - either the lab is ready to submit, or it is late and hence worth zero.
• Students are allowed only ONE single-day late submission without penalty. This is a once only one-day extension ... once used, any further late submission will receive an automatic zero.
(This policy reflects expectations in the real world: to be late for work, once, will likely not result in termination however chronic late arrivals will almost certainly result in job loss. Develop good work ethic _now_.)
• Students must pass the theory (testing) and practical (lab/assignment) portions of the course separately in order to receive a passing grade. If a failing grade is received in either portion, then the lower of the two marks (theory or practical) will become the final grade.
• In order to be considered for supplementary evaluation (SE) upon failure in this course, a mark of 50% minimum will be required in the practical (lab/assignment) portion of the course plus a mark of 45% minimum in the theory (testing) portion. A theory mark of 44% or less, or a lab mark of 49% or less, will result in failure with no SE option.

Complete course policies can be found in the Teaching and Learning Plan (T&LP) document found on Blackboard.

Textbook

Fundamentals of Light Sources and Lasers by Csele, 2004, John Wiley & Sons, ISBN 0-471-47660-9

Chapters 1 to 5 and 9 are covered in this course. The rest of the text is covered in the next course

Unit 1: Light and Atomic Emission (Chapters 1&2 of the text)

The fundamental nature of light itself will be examined including the processes of emission and absorption and the fundamental concepts of atomic energy levels and laws governing these. As well as blackbody radiation, line spectra (e.g. from an electrically-excited gas discharge) will be examined. Experiments such as that of Franck-Hertz will be used to illustrate the behavior of energy levels. Finally, semiconductor light sources (e.g. LEDs and lasers) will be examined with an emphasis on the physics of junctions and band gaps

Unit 2: Quantum Mechanics (Chapter 3 of the text)

This section is meant to provide the student with a 'survival guide to quantum mechanics' as required to understand basic light emission and laser action - it is not meant to be all-encompassing nor exhaustingly thorough since an advanced quantum course is included in the program curriculum. We begin with a look at the development of quantum mechanics as stemming from problems evident in classical models. Evidence of wave behaviour in electrons is presented and basic wave mechanics (i.e. wave equations for particles) are introduced. Quantum concepts of energy levels, angular momentum in quantum states, and electron spin are then introduced with experimental evidence (e.g. in the form of the Stern-Gerlach experiment) provided to support the existence of these. Spectroscopic Notation, required when examining the energy levels of a given species, is also examined.

Unit 3: Introduction To Lasers (Chapter 4 of the text)

A cornerstone of this course, we begin with a look at the characteristics of coherent light and quickly move to understand the mechanisms to coax coherent emission from an atomic species. Using concepts from unit 1 (such as the Boltzmann distribution) the concepts of a population inversion is examined. Laser gain, as generated by stimulated emission, is then detailed. Basic mathematical models for the laser based on gain and loss are developed (including the calculation of threshold gain) and the requirements for a resonator are demonstrated. In a practical sense, concepts studied in this chapter are augmented by lab work involving the alignment of a laser resonator, and determination of pumping threshold for both semiconductor and YAG lasers. The familiar helium-neon gas laser will be used extensively throughout this unit as an illustrative example.

Unit 4: Mathematical Modelling of Lasing Transitions and Mechanisms (Chapter 5 of the text)

Delving further into the mechanism of the laser we examine three and four level energy schemes and rate equations governing these. Various pumping mechanisms are examined and the effect of atomic parameters such as level lifetime are illustrated. The important concept of gain saturation is illustrated, both mathematically and in a lab experiment, and various parameters are examined leading to the production of a simple mathematical model predicting the operation of the laser itself.

In the next course, resonators will be examined and modelled (both using sum-of-losses and distributed loss techniques), short-pulse techniques (Q-switching and modelocking) and non-linear optics (harmonic generation) will be examined in detail. Specific mechanisms of various lasers including ion, nitrogen and excimer, carbon-dioxide, YAG (including DPSS) and ruby lasers will be examined.

Course Notes and Links

Lab References:
• NIST eBook of Atomic Spectral Data as required for several labs in this course
• Notes On Lab Reports details what is required for a lab report in this course
• Notes On Lab Reports II with an advanced discussion on both formal and informal lab reports


• Using a Spectroscope the basic theory and use of the spectroscopes in lab 1
• Spectroscopes a reference on using a spectroscope as required for Labs 1 and 2 (Password-protected PDF)
• Photomultiplier Tubes the basic operation of these tubes as required for lab 2

Lecture Notes:
• Chapter 1 and 2 notes on Blackbody radiation and atomic emission (Password-protected PDF)
• Chapter 3 - Quantum Intro notes on introductory quantum mechanics concepts (Password-protected PDF)
• Quantum Terms a summary of how to compute quantum terms and determine allowed transitions: concentrate on the single-electron case (Password-protected PDF)
• Midterm #1 Preview a collection of practice questions (with answers, but not full solutions) (Password-protected PDF)


• Laser Gain a review of important concepts (Password-protected PDF)
• Pre-Lab #5 Notes from the in-class presentation. Also contains a good example for study purposes (Password-protected PDF)
• HeNe Visible Gas Laser the development of the visible HeNe laser from the OSA www.osa.org to which all student have access from any college computer. Makes an excellent review after lab #4 of major concepts! (Password-protected PDF)
• Midterm #2 Preview a collection of practice questions (with answers, but not full solutions) (Password-protected PDF)


• Cross Sections and Gain from the in-class presentation during week 9 (Nov 1) (Password-protected PDF)
• Power Development in a HeNe output of the simulation (from class) (Password-protected PDF)
• Neutral Neon Transitions from the in-class presentation (Password-protected PDF)

Test #3 Review:
• Helium-Cadmium Example from the in-class presentation (Password-protected PDF)
• Helium-Cadmium Solution numerical solutions to the presentation (Password-protected PDF)
• Helium-Cadmium Hints if you're really stuck, a few hints to get you started ... try it yourself first, though, as hints will not be given on the actual test! (Password-protected PDF)
• Thermal Gain Example a second study example (Password-protected PDF)
• Entrance Exam for PHTN1400 a _minimal_ standard for entry into PHTN1400, from the in-class presentation (Password-protected PDF)
• Formula Sheet for the third test

Useful Links

• NIST eBook of Atomic Spectral Data as required for several labs in this course
• Hyperphysics by C.R. Nave ...a complete Web-based physics reference
• Quantum Mechanics Primer from the Homebuilt Lasers Site (opens in a new window)
• Physical Simulations of Light and Radiation (including Lasers) from PhET (U of Colorado)

Equipment Manuals and SOPs

• Standard Operating Procedures (SOPs) for laboratory equipment.

Class Schedule (completed/planned)

Week 1 2011/09/09:
  Course introduction, policies, labs, evaluation, and overview
  Chapter 1 and 2
  Blackbody radiation, Quantization
Week 2 2011/09/12:
  Quantization, Photoelectric effect, FHz experiment, Fluorescence
  Semiconductor sources
  LAB #1: Basic Spectroscopy
    PRELAB DUE at the beginning of the lab 
Week 3 2011/09/19:
  Chapter 3
  Quantum Mechanics
  LAB #1: Basic Spectroscopy (Parts C & D)
Week 4 2011/09/26:
  Quantum Mechanics - Multielectron case
  Chapter 4
  Start of Lasers - Properties, Inversions, Pumping, Stimulated Emission
  LAB #2: Advanced Spectroscopy
Week 5 2011/10/03:
  Midterm #1 Preparation
  LAB #3: Selective Pumping
Week 6 2011/10/10:
  Midterm #1 In Class on Tuesday (one hour)
  Return and Review Midterm on Thursday
Week 7 2011/10/17:
  Laser Gain
  Threshold gain calculations
Week 8 2011/10/24:
  Windows
  Gain Measurement techniques
  Pre Lab#5 Concepts
  Lab #3 Due
  Lab #4
Week 9 2011/10/31:
  Three and Four level lasers (Csele 5.2)
  CW and Pulse laser action (Csele 5.3)
  Depopulation of LLL in 4-level lasers (Csele 5.4)
  Rate equations (Csele 5.5-5.7)
  Midterm #2 Prep and Review
  Lab #4 Due
  Lab #5 (Part 1 of 3)
Week 10 2011/11/07:
  Term Test #2 (in class)
  Return and review test #2
  Cross-section and Gain
  Lab #5 (Part 2 of 3)
Week 11 2011/11/14:
  Cross-section and Gain
  Lab #5 (Part 3 of 3)
Week 12 2011/11/21:
  HeNe case study
    Effect of shared energy levels on transitions
    Suppression of IR transitions
  Lab #5 Due
  Lab #6 (semiconductor pumping threshold)


Week 13 2011/11/28:
  HeCd example (complete)
  Lab #6 Due
Week 14 2011/12/05:
  Term Test #3 (in class, Thursday, two hours)
 

Laboratories and Assignments

There are five major labs in this course. Some labs require extensive background research (e.g. in solid state laser design in order to compute the gain of a diode laser in lab 4). Some require a complete lab report ranging from 5 to 15 pages containing sections outlining background, procedure, observations, and conclusions. The format of lab reports is outlined here. As well, some lectures will be conducted in the lab period.

NOTE: While observed results (numbers only) may be identical for more than one student, no other portions of the lab are to be shared. Where procedures, analysis, graphs, and/or conclusions are suspected to be plagiarized, labs will be submitted to the dean's office and all students involved will receive a mark of zero. "Sharing" answers and analysis often equates to "Plagiarism" which is academic misconduct and will be treated accordingly.

Lab 1: Introduction To Spectroscopy
Basic spectroscopy of the emissions of various light sources are performed using two types of grating instruments. Emissions from broadband sources such as incandescent and fluorescent sources are first analyzed using a manual spectroscope. Atomic spectra from several pure gases in spectrum tubes (e.g. Hydrogen and Mercury) are then analyzed and related to energy level transitions in the atomic species. Students will also be given an unknown spectral source (a spectrum tube with an unknown gas) and be required to identify the gas via its spectral emissions using a high-resolution computer-based Ocean Optics spectrograph.
Lab Weighting: 2.0
Part A&B on week 2 (2011/09/16) - Prelab also due at this time; Part C&D on week 3 (2011/09/23)
Full Lab Report due at the beginning of the lab on week 4. Failure to submit this lab BEFORE on ON the due date and time will result in an immediate ZERO on the lab and placing of the student on course condition (meaning one more late or missing lab results in immediate EXPULSION from the course without recourse).
PRELAB due on entry to first lab period (week 2)
Lab 1 Marking Scheme (Example only)

Lab 2: Advanced Spectroscopy
Students will use both manual spectrometers (Coleman-20 and GeneSys units) and automated spectrophotometers (Perkin-Elmer Lambda-3B dual-beam automated spectrograph). The operation of single-beam, manual units and the Dual-beam unit (Perkin-Elmer Lambda 3B) will be compared. Skills developed in this lab will be employed in numerous courses (including PHTN1432: Thin film and High Vacuum next term).
Lab Weighting: 1.0
Lab on week 4 (2011/09/23)
Condensed Lab Report (with questions) due on week 5

Lab 3: Selective Pumping in a gas laser
The role of helium in pumping the ULL of a helium-neon gas laser will be investigated and experimental proof will be furnished to show how selected levels can be excited. In order to perform the experiment and resolve the tightly-clustered emission lines of neon a McPherson 1m monochromator with PMT detector is employed.
Lab Weighting: 1.0
Lab on week 6 (2011/10/14)
Condensed Lab Report (with questions) due on week 7 (2011/10/21)

Lab 4: HeNe Lasers
Basic electronics and laboratory skills will be developed while investigating the operation of the helium-neon gas laser. Students will wire a 'bare' gas laser tube to a power supply. As part of an assignment optical and electrical characteristics will be investigated and students will be introduced to application of the gain threshold equation.
Lab Weighting: 1.0
Lab on week 7 (2011/10/21)
Condensed Lab Report (with questions) due on week 8 (2011/10/28)

Lab 5: Gas Laser Cavity Optics
A 'bare' helium-neon gas laser tube with completely external optics will be setup and the mechanics of this laser will be studied. The student will build the entire optical resonator on an optical breadboard and align cavity optics. Various electromagnetic modes (TEM_xx) will be observed when aligning the optics. Next, gain will be determined by inserting a glass slide intra-cavity at various angles. This glass slide will render a loss ranging from close to 0% at Brewster's angle (polarized) to 8% at perpendicular. By summing all losses in the laser gain may be determined.
Lab Weighting: 2.0
Part A on week 9
Part B on week 10
Part C on week 11
Full Lab Report due at the beginning of the lab period on week 12
Lab 5 Marking Scheme example

Lab 6: Lasing threshold of a Semiconductor Laser
In the lab, several key physical parameters of a commercial-grade semiconductor diode laser are determined and from these a model is developed to predict the threshold current of the device (following question 5.9 on page 158 of Csele).
Lab Weighting: 1.0
Lab on week 12
Condensed Lab Report (with questions) due on week 13

Contacts:

For the Advanced Lasers programs ...
Program Coordinator - Dr. Ben Cecil
Telephone (905) 735-2211
E-Mail: (Be sure to include 'Photonics' in the subject line to avoid deletion by an anti-spam filter)

For this specific course ...
Professor Mark Csele
Telephone (905) 735-2211 x.7629
E-Mail: (Be sure to include 'Photonics' in the subject line to avoid deletion by an anti-spam filter)
URL: http://technology.niagarac.on.ca/people/mcsele

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Copyright (C) Mark Csele and Niagara College, Canada, 2005-2011
Some images and text excerpted from Fundamentals of Light Sources and Lasers by Csele, John Wiley & Sons, 2004, ISBN 0-471-47660-9 and hence are Copyright © John Wiley and Sons. Further reproduction in any form is prohibited without written approval from the publisher.
This course is part of the TECHNOLOGY division