Undergraduate Laser Laboratory at SJSU Ken Wharton SJSU
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): – – – – Laser and Electrical Safety Mounts/hardware (built from scratch each week) Optics handling/cleaning Beam pointing + centering (He. Ne laser) Power measurements (He. Ne laser) ND Filters/Attenuation (Only actual experiment) Scientific Writing Techniques Need 4 sets of everything in these labs. (Optical Tables, ND Filters, power meters, He. Ne lasers, mirrors, hardware. . . )
Primary Experiments • • Align He. Ne cavity; current vs. power (*) Polarization Lab ( /2, /4 plates, Pockels cell) CCD Lab, Gaussian Beam Propagation Photodetector response time (chopped He. Ne) He-Ne Beam Amplification / Saturation Intensity (*) CO 2 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, He. Nes, Optics, Hardware. . .
He. Ne Discharge Tube 1 st experiment: Use reference He. Ne to align mirrors, optimize power output, plot discharge current vs. power. 2 nd experiment: Increasing input power lowers gain (from ~15% to ~5%) allowing estimation of saturation intensity for He. Ne.
CO 2 Laser Experiment • One mirror fixed; one mirror adjustable (students align with reference He. Ne) • Maximum power ~ 500 m. W • 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. 1 st-order laser theory e. g. Gaussian Beam Lab, introduce M 2≠ 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
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