Undergraduate Laser
Laboratory at SJSU
Ken Wharton
SJSU Physics Department
• 4 of 14 full-time faculty members with
laser/optics research background
• Houses “Institute for Modern Optics”
(contact rdbahuguna@aim.com for more info)
• Located in the heart of Silicon Valley
Instead of a typical “Advanced Laboratory”,
our department instead offers an optics
laboratory and a laser laboratory for our
upper-division majors.
Laser Laboratory: Overview
• 4 optical tables; 8 students/section
• 4 hours/week (2 units)
• No write-up time in class
The first few labs
are identical for
all students.
Then the students
rotate through two
sets of four labs.
Introductory “Experiments”
• Labs 1 & 2 (same for all students):
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Laser and Electrical Safety
Mounts/hardware (built from scratch each week)
Optics handling/cleaning
Beam pointing + centering (HeNe laser)
Power measurements (HeNe laser)
ND Filters/Attenuation (Only actual experiment)
Scientific Writing Techniques
Need 4 sets of everything in these labs.
(Optical Tables, ND Filters, power meters,
HeNe lasers, mirrors, hardware...)
Primary Experiments
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Align HeNe cavity; current vs. power (*)
Polarization Lab (/2, /4 plates, Pockels cell)
CCD Lab, Gaussian Beam Propagation
Photodetector response time (chopped HeNe)
He-Ne Beam Amplification / Saturation Intensity (*)
CO2 laser (homemade system) (*)
Argon-Ion laser (multi-line, diffraction grating expt.)
Interferometry (index of refraction of air)
Donated equipment includes CCD camera, optical
tables, power supplies, HeNes, Optics, Hardware...
HeNe Discharge Tube
1st experiment: Use reference HeNe to align mirrors,
optimize power output, plot discharge current vs. power.
2nd experiment:
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Increasing input power lowers gain (from ~15% to ~5%)
allowing estimation of saturation intensity for HeNe.
CO2 Laser Experiment
• One mirror fixed; one
mirror adjustable (students
align with reference HeNe)
• Maximum power ~ 500mW
• Students try different
output couplers
• Beam size estimated from
burn spot on paper
• Students compute gain
coefficient, efficiency
Final Thoughts
• Lab complements laser course
– Usual reasons: Hands-on learning, etc...
– The real world vs. 1st-order laser theory
e.g. Gaussian Beam Lab, introduce M2≠1
– Lab experience key for jobs in photonics
• If interested in more info, please contact me:
– Ken Wharton, wharton@science.sjsu.edu
Thanks: Sarma Lakkaraju, Kiumars
Parvin, Ramen Bahuguna, Jose Garcia