VCSEL Optical Clock Using Subwavelength Quarter-Wave Plate
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CLEO 2009: High Frequency Polarization Switching VCSEL Clock Using Subwavelength Quarter-Wave Plate by: Clinton J. Smith, Wen-Di Li, Shufeng Bai, and Stephen Y. Chou
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VCSEL Optical Clock Using Subwavelength Quarter-Wave Plate
- 1. Clinton J. Smith, Wen-Di Li, Shufeng Bai and Stephen Y. Chou NanoStructures Laboratory, Princeton University CLEO/IQEC 2009 High Frequency Polarization Switching VCSEL Clock Using Subwavelength Quarter-Wave Plate NanoStructures Lab Princeton University Supported in part by DARPA
- 4. Comparison to Atomic Clocks Developed by Knappe & Jau Y. Y. Jau, E. Miron, A. B. Post, N. N. Kuzma, and W. Happer, "Push-Pull Optical Pumping of Pure Superposition States," Physical Review Letters, vol. 93, p. 160802, 2004. S. Knappe, V. Shah, P. D. D. Schwindt, L. Hollberg, J. Kitching, L.-A. Liew, and J. Moreland, "A microfabricated atomic clock," APPLIED PHYSICS LETTERS, vol. 85, pp. 1460-1462, 2004. *Does not include current modulation electronics ** Designed for Rb resonance lock 4.6 GHz 3.4 GHz ** 4.6 GHz Frequency N/A Yes Yes Cs/Rb Resonance Lock Polarization Self-Switching Laser Intensity Modulation Current Modulation Operating Principle 5-10 mW N/A 5 mW Power Consumption 3 8 6 Number of Optical Elements ~1.7 cm 3 optical bench top < 1 cm 3 * Size Smith Jau Knappe
- 11. VCSEL Clock Oscillation Frequency Governed by Cavity Length Independent Component Mount Integrated Component Mount 25 dB 20 MHz 3.88 GHz 3.67 GHz 3.45 mA 2.04 cm 25 dB 8.5 MHz 4.6 GHz 4.58 GHz 4.28 mA 1.64 cm SNR FWHM Measured Oscillation Frequency Theoretical Oscillation Frequency VCSEL Drive Current Cavity Length
- 12. VCSEL Clock Oscillation Frequency Changed With Drive Current 3.45 mA Drive Current 5.58 mA Drive Current 2.97 mA Drive Current 30 dB 6 MHz 7.22 GHz 5.58 mA 3.67 GHz 2.04 cm 25 dB 6 MHz 5.63 GHz 2.97 mA 3.67 GHz 2.04 cm 25 dB 20 MHz 3.88 GHz 3.45 mA 3.67 GHz 2.04 cm SNR FWHM Measured Oscillation Frequency VCSEL Drive Current Theoretical Oscillation Frequency Cavity Length
Editor's Notes
- Our setup uses a VCSEL which can be made to switch polarization on its own by introducing the other polariztion into the cavity. The graph above (you can click through the next few slides for a crude animation) shows how the VCSEL emits linear polarized light which then passes through the quarter--wave plate and is converted to circular. A partial reflector then takes the circular polarization and flips its handedness. Now the circular polarizied light passes though the QWP again and is converted into the opposite linear polarization and this causes the VCSEL to flip its lasing polarization. Rinse and repeat ad infinitum…
- Here are some oscillations with the other cavity setup. You can see they are much cleaner than the previous ones. You can also see how the frequency is shifted by changing the drive current of the VCSEL (in the last case of the spherical PR, the reflector itself was moved to change the frequency). So you can see there appear to be two methods of monkeying around with the frequency.
- Our setup uses a VCSEL which can be made to switch polarization on its own by introducing the other polariztion into the cavity. The graph above (you can click through the next few slides for a crude animation) shows how the VCSEL emits linear polarized light which then passes through the quarter--wave plate and is converted to circular. A partial reflector then takes the circular polarization and flips its handedness. Now the circular polarizied light passes though the QWP again and is converted into the opposite linear polarization and this causes the VCSEL to flip its lasing polarization. Rinse and repeat ad infinitum…
- Here are some oscillations with the other cavity setup. You can see they are much cleaner than the previous ones. You can also see how the frequency is shifted by changing the drive current of the VCSEL (in the last case of the spherical PR, the reflector itself was moved to change the frequency). So you can see there appear to be two methods of monkeying around with the frequency.
- Here are some oscillations with the other cavity setup. You can see they are much cleaner than the previous ones. You can also see how the frequency is shifted by changing the drive current of the VCSEL (in the last case of the spherical PR, the reflector itself was moved to change the frequency). So you can see there appear to be two methods of monkeying around with the frequency.