Post on 21-Sep-2020
Fiber Laser for ERL
Zach Ulibarri Mentor: Zhi Zhao
Introduc:on • Goal: – Mode locked laser oscillator – 50 MHz repe::on rate
– Designed for emiEance measurement
Laser Basics • Popula:on inversion in gain medium
Laser Basics • S:mulated photon emission
Laser Basics • Light emits and repeats process
Mode Locked Lasers • Saturable absorber
Intensity
Transmission
Mode Locked Lasers
• With saturable absorber in place, random noise can create pulses
Mode Locked Lasers
• How do we add sufficient noise to the cavity?
Mode Locked Lasers
• How do we add sufficient noise to the cavity?
Ar:ficial Saturable Absorber • Wave plates create phase shiS induced intensity modula:on
Experimental Setup
Top View
Mode Locked Lasers
19.8ns
Mode Locked Lasers • Detector is too slow
FWHM suggests Pulse width = 1.22 ns
Autocorrelator Measurement • Michelson interferometer creates small delay • Aligned pulses create second harmonic genera:on
Intensity Autocorrela:on
Intensity Autocorrela:on
FWHM suggests pulse width = 8ps. Very large!
Chirp • Index of refrac:on depends on wavelength
• Compensate with diffrac:on gra:ng
Chirp
Intensity Autocorrela:on
Dechirped Autocorrela:on
Dechirped Autocorrela:on
FWHM = 330 fs = 1.5*220
Interferometric Autocorrela:on
FWHM suggests pulse width = 220fs
Spectrum
Simulated Results
200fs
Agrees with es:mates
Pulse Energy • Peak power es:mated from pulse energy and characteris:cs Chirped Dechirped
"↓$%&'( = *↓+,- // "↓$%&'( = *↓+,- //
= 20301/50.5∗ 10↑6 = 53.301/50.5∗ 10↑6
=1.0634 =4.0234
Peak Power
*↓$(+5 = "↓$%&'( /6↓$%&'(
= 1.06 ∗10↑−9 /200∗10↑−15
=5.2851
*↓$(+5 = "↓$%&'( /6↓$%&'(
= 4.02 ∗10↑−9 /200∗10↑−15
=20.151
Chirped Dechirped
Ques:ons?