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Course Info | Class Notes | Evaluation / Check Marks | Labs

A continuation of PHTN9120, this course provides an examination of specific laser systems and laser processes with the goals of providing practical experience and producing mathematical models of the laser. Power sources, excitation mechanisms, quantum processes, beam characteristics, and emission spectra for a selection of key commercial and research lasers including ion, CO2, excimer, YAG, ruby, and dye types will be examined. Specific features investigated include wavelength selection (for multi-line lasers), single frequency operation using intra-cavity etalons, pulse generation techniques (including Q-switching and modelocking), the operation of both acousto-optic and electro-optic modulators and switches, and non-linear optics (harmonic generation and OPO). Laser processes modeled include saturation of gain in an amplification medium, the modeling of lasers to optimize elements such as cavity optics, and the modeling of Q-switched lasers to predict output power, available energy, and key timing parameters. A laboratory component allows students to investigate lasing mechanisms and processes as well as the workings of practical lasers.

A tunable titanium-sapphire laser in the advanced laser lab.

Prerequisites

PHTN9120 Fundamentals of Light Sources and Lasers


This course is offered as part of the Advanced Lasers Program in Photonics

Evaluation ...

Three term tests valued at 20% each
TERM TEST #1: In Class Monday Feb 11, 2013
• Safety (Calculating OD of glasses, NHZ, laser regulations)
• Quantum mechanics of shared levels (including questions from lab 1)
• CW Gas laser power supplies and tube design (HeNe & Ion, Basic Electronics, Tube structure, Maintenance, Gas Issues)
• Resonators, modes (FSR), cavity optics (including stability criteria), wavelength selection (including mirror design), etalons
• CO₂ lasers, low-pressure design only (Electronics, IR optics, cavity stability, role of gases, including material from various presentations)
• All material from lab 1
• Chapters 3-5 (all background from PHTN1300), 6, 9, 11
• Everything in "HeNe Lasers", "HeNe Case Study", "Ion Lasers", "SP Intro", and "CO2 Lasers Low Pressure" documents
TERM TEST #2: In Class Monday, March 18, 2013
Basic Knowledge
• Safe use of lasers (choosing safety glasses based on OD)
• TEA and Excimer lasers (including circuit design, discharge dynamics, E/P ratio)
• E/P ratio in gases (including material from the presentation and labs)
• Solid-State lasers (up to Q-Switching)
• SS Lasers: Thermalization of LLLs and Gain calculations
• SS Lasers: Pumping techniques (flashlamps/arc/diode), Wavelength stability of diode pump sources
• All material from lab #3
• Chapters 3-5 (all background from PHTN9120), 10, 12
• Everything in "E/P Ratio", "CO2 Lasers - TEA", "Pulsed Gas Lasers", and "Solid State Lasers" notes
Mathematical Skills
• Calculating the required OD of safety glasses
• Calculating optimal gas fill for excimer and CO2 lasers based on E/P ratio
• Calculating gain of a solid-state laser, thermal populations, re-absorption loss, Stark levels, effective gain

TERM TEST #3 : In Class Monday, April 15, 2013
• Safe use of lasers (choosing safety glasses based on OD)
• Q-Switching and Modelocking (Fast-pulse techniques)
• Calculating the holdoff required of Q-Switches
• AO, EO modulators: calculations of %T
• Calculating transmission of EOM switches
• AOM/PCAOM: Bragg angle and DE computations
• Modelocking: calculating switch rates
• SHG: Efficiency, damage threshold, n-wave mixing
• All material from lab #4 and lab #5
• Numerical models for predicting optimal gain in a Q-switched laser
• Convolution models for predicting the effect of pump diode wavelength drift
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.

Textbook

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

Chapters 6 through 15 are covered in this course.




Course Notes

Classroom Presentations and Links to Augmenting Material:
Pre-lab Material ...

• Standard Operating Procedures (SOPs) for lasers in Niagara College's high powered laser labs.
• Laser Safety For Students from the in-class presentation.
• Coherent.Com where you may download the laser safety video shown in class. Also, some manuals for our Coherent lasers are available here.
Watching this video, and writing a quiz BEFORE the first lab is MANDATORY!

CW Gas Lasers ...

• Entrance Exam Solution useful for identifying areas requiring academic attention. (The examination was given last term).
• Helium-Neon Lasers from the in-class presentation. Covers HeNe lasers and wavelength selection via optics.
• HeNe Gas Laser - Case Study outlining issues such as competition for ULL (good prep for the term test).
• Ion Lasers from the in-class presentation. Covers Ion lasers as well as longitudinal modes, linewidth, and use of etalons.
• Ion Lasers - A Summary from a Spectra-Physics manual. A good overall review of ion lasers.
• A few links for the unit on ION LASERS:
  • History of Gas Lasers from Optics & Photonics News published by the OSA (must be opened from a college computer).
  • Sam's Laser FAQ on Ion Lasers including discussions of gas pressure issues ("spectral balance") in Ar⁺ and Kr⁺ lasers
• CO2 Lasers - Low Pressure primarily covering quantum mechanisms of the CO2 laser as well as design of CW lasers.
• A few links for the unit on CO2 LASERS:
  • Sam's Laser FAQ on Homebuilt CO2 Lasers including discussions on optics

Pulsed Gas Lasers ...

• E/P Ratio covering design issues with nitrogen, excimer, and CO₂ gas lasers.
• E/P Graph allowing determination of the E/P ratio for nitrogen gas.
• CO2 Lasers - TEA primarily covering E/P issues, preionization, and discharge circuit design.
• Pulsed Gas Lasers primarily covering Excimer and Nitrogen lasers and discharge circuit design.

Solid-State Lasers and Q-Switching...

• Solid State Lasers the in-class presentation. (Password protected PDF).
• Modeling Pump Diode Effects the in-class presentation. (Password protected PDF).
• Pre-Requisite (Review) Material for Solid-State Lasers, Q-Switching, and Term Test #2 ...
  • Laser Gain from the in-class presentation (the most important concept from last term!) (Password-protected PDF). Contains an example question about Q-Switch holdoff which is an excellent introduction to Q-Switching.
  • Cross-Sections and Gain from the in-class presentation (the second most important concept from last term!) (Password-protected PDF). Contains an example question pertaining to computation of inversions and thermalization of the LLL.
  • Thermal Populations and Gain (Password-protected PDF). A complete example on computing thermalization of the LLL and gain.
• Q-Switching Notes including AOM and EOM switches (Password protected PDF)
• Modeling Solid State Lasers Developing a model to determine optimal Q-switching time (Password protected PDF)
• Harmonic Generation Password protected PDF file.
• Dye Lasers Password protected PDF file.
General Notes:
• Notes on Lab Reports a tutorial on writing formal lab reports.
• Notes on Lab Reports, Part 2 a tutorial on writing condensed lab reports.
• Midterm #1 Preparation Questions a selection of example questions from previous midterm examinations as covered in class (solutions done in review class). Password protected PDF file.
• Term Test #1 Formula Sheet.
• Midterm #1 SOLUTION.
• Midterm #2 Preparation Questions a selection of example questions from previous midterm examinations as covered in class (solutions done in review class). Password protected PDF file.
• Final Review Questions from a previous review class.
• Final Exam Review Questions a host of questions from various sources as practice for the final exam.
• Final Exam Formula Sheet a typical formula sheet from a previous exam.
• Term Test #3 Review Questions from previous tests and class presentations.
Reading List: (Scientific American Amateur Scientist Articles available on CD in the library or from L-18 for sign-out)
• September 1964 How a Persevering Amateur Can Build a Gas Laser in the Home (HeNe Laser)
• December 1965 Deep Sky Photographs with a 35-Millimeter Camera and More about the Homemade Laser (Follow-Up to the above article)
• October 1980 A Homemade Mercury-Vapor Ion Laser That Emits Both Green and Red-Orange (Hg⁺ Laser)
• Feburary 1969 How to Construct an Argon Gas Laser with Outputs At Several Wavelengths (Ar⁺ Laser)
• June 1974 An Unusual Kind of Gas Laser That Puts Out Pulses in the Ultraviolet (N₂ Laser)
• Feb 1970 A Tunable Laser Using Organic Dye Is Made At Home for Less Than $75


Laboratories and Assignments (2013 Winter)

Lab #1: Safe Operation of Lasers
The safe operation of lasers is examined including use of high-powered ion lasers. In the lab, the concept of Nominal Hazard Zone (NHZ) and optical density (OD) will examined with respect to correctly choosing safety glasses for specific lasers. The operating procedures of large ion lasers will also be demonstrated including use of current and light regulation modes, optics changes, and procedures to maintain a laser such as this.
WARNING:
  Safety Quiz on BLACKBOARD is due by Tuesday 2013/01/15 BEFORE admission to this lab. NO EXCEPTIONS: NO SUCCESSFUL QUIZ, NO LAB ADMISSION (And a mark of ZERO will result)
Lab Sessions:
  Group A - Part A on 2013/01/16, Part B on 2013/01/23
  Group B - Part B on 2013/01/16, Part A on 2013/01/23
  All Sections DUE on 2013/02/30 (at the beginning of the lab period)


Lab #2: Cavity Alignment
A skills-based lab in which the alignment of the optics of two types of lasers will be completed. First, the optics on a large-bore MPB IN-100 carbon-dioxide laser will be aligned using a coaxial HeNe laser beam. Burn patterns will then be used to analyze beam structure under optimized and non-optimal conditions. Next, the optics (HR, OC, and Fold Mirrors) on a Coherent argon-ion laser-pumped dye laser will be removed and aligned by using the fluorescence of the dye itself to provide alignment 'spots'. A lab report will outline details of the procedure.
Lab Sessions:
  Group A - Part A on 2013/01/30, Part B on 2013/02/06
  Group B - Part B on 2013/01/30, Part A on 2013/02/06
  All Sections DUE on 2013/02/13 (at the beginning of the lab period)


Lab #3: Pulsed Gas Lasers
Students will mix various gas fills for a Lumonics Excimer 500 and a Lumonics TEA-203 CO₂ laser in V15 and will study the effect on power output. In the excimer laser, a Helium-Nitrogen mixture will be employed with various concentrations of nitrogen (the active lasing species) and the effect of nitrogen concentration on output power noted. In the TEA laser pressure and voltage will be varied. Results will be correlated with the calculated E/P ratio of the gases employed.
Additional PreLab Question (submit with the lab report):
Compute the expected E/P ratio for nitrogen. Use a similar argument to that used by Calvert for neon gas in the prelab reading (you must use the ionization energy for nitrogen, see section 5: arc discharge of the reading or use NIST tables).
Lab Sessions:
  Group A - Part A on 2013/02/13, Part B on 2013/02/20
  Group B - Part B on 2013/02/13, Part A on 2013/02/20
  All Sections DUE on Monday 2013/03/04 (in class, immediately after March Break)


No Lab on March Break

Lab #4: DPSS Lasers NEW for 2013
A complete overview of DPSS design concepts including the characteristics of pump diodes, absorption characteristics of vanadate (Nd:YVO₄), temperature sensitivity of harmonic generators (phase-matching), and re-absorption losses in solid-state laser media. Includes a quantum analysis of vanadate (e.g. Stark level splitting).
Lab Weight:
This lab is weighted heavier (1.5 times) than other labs in this course
Pre Lab:
A prelab is due upon entering the lab for the first of the two lab sessions. This prelab is worth 25% of the lab and will receive a mark of ZERO if not produced immediately upon entry to the lab. The prelab involves significant reading and calculations - start it early.
Lab Sessions:
  Group A - Part A on 2013/03/13, Part B on 2013/03/20
  Group B - Part B on 2013/03/13, Part A on 2013/03/20
  All Sections DUE on 2013/03/27 (at the beginning of the lab period)


Lab #5: Q-Switched Lasers
A complete overview of Q-Switched lasers including the operation and alignment of practical AOM switches, as well as time-domain modeling of inversion buildup in a flashlamp-pumped Q-Switched Nd:YAG laser. By monitoring the flashlamp intensity of a solid-state YAG laser, a model is developed to predict the inversion, and hence the gain, as it develops in time taking into account both pumped population as well as spontaneous decay. Results of the model are compared to actual experimental results. In this manner, the optimal time to open the Q-switch may be predicted.
Lab Weight:
This lab is weighted heavier (1.5 times) than other labs in this course
Pre Lab:
A prelab is due upon entering the lab for the first of the two lab sessions. This prelab is worth 10% of the lab and will receive a mark of ZERO if not produced immediately upon entry to the lab. The prelab involves significant reading and calculations - start it early.
Lab Sessions:
  Group A - Part A on 2013/03/27, Part B on 2013/04/03
  Group B - Part B on 2013/03/27, Part A on 2013/04/03
  All Sections DUE on 2013/04/10 (at the beginning of the lab period)




Contacts:

For the Photonics Technician/Technology/Advanced Lasers programs ...
Program Coordinator Alexander McGlashan
Telephone (905) 735-2211 x.7513
E-Mail:



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 - 2013
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