1	Advances on Portable Frequency References in LUMOS Kansas State University Kevin Knabe
2	Outline Goals Overview of Frequency Standards Saturated Absorption Spectroscopy Fiber Cells Reflected Pump Setup (single beam!) Locking Update on the Cr:F Laser
3	Goals Studying ν₁ + ν₃ vibrational band of acetylene (optimize signal for locking) Create an acetylene cell using Photonic BandGap (PBG) Fiber and Single Mode Fiber (SMF) Lock a laser to absorption signal
4	Acetylene as Frequency Reference Moderate accuracy (± 100 MHz) High accuracy ( ±2 kHz)
5	Saturated Absorption
6	Theory of Saturated Absorption
7	Pump-Probe Setup
8	Photonic Bandgap Fibers “10 mm fiber”- 7 missing cells 7.5 μm mode field diameter
9	Typical Data
10	Pressure Results
11	Power Results
12	Goals Studying ν₁ + ν₃ vibrational band of acetylene (optimize signal for locking) Create an acetylene cell using Photonic BandGap (PBG) Fiber and Single Mode Fiber (SMF) Lock a laser to absorption signal
13	The Splice is Right
14	Making Fiber Cells
15	Goals Studying ν₁ + ν₃ vibrational band of acetylene (optimize signal for locking) Create an acetylene cell using Photonic BandGap (PBG) Fiber and Single Mode Fiber (SMF) New Goal: Check quality of half cells Lock a laser to absorption signal
16	Saturated Absorption Spectroscopy With Only 1 Beam in PBG Fiber*
17	Pump-Probe Setup for Spliced Half-Cells
18	Pump-Probe Setup for Spliced Half-Cells – No AOM
19	Reflected Pump Setup
20	R-Pump Results: Signal Quality
21	R-Pump Results: Comparison Of Widths
22	Goals Studying ν₁ + ν₃ vibrational band of acetylene (optimize signal for locking) Create an acetylene cell using Photonic BandGap (PBG) Fiber and Single Mode Fiber (SMF) Check quality of half cells Lock a laser to absorption signal, then compare with locked Cr:F frequency comb
23	Locking Lock laser to sat. abs feature. Measure with comb referenced to GPS. Lock comb to fiber-based reference, output stable microwaves.
24	Chromium Forsterite Update
25	Cr:F Spectra
26	f-2f Interferometer
27	Conclusion Characterization has been done on acetylene filled PBG fibers Advances have been made on making gas filled cells Discovery of the Reflected-Pump technique Cr:F is close to being locked! Next: Lock Laser to saturated absorption signal
28	Thanks Funding Agencies: AFOSR NSF CAREER Kansas NSF EPSCoR program Kansas Technology Enterprise Corporation Kansas State University Mike Wells and the JRM Staff