The CU/NIST Laser Frequency Comb Calibrator for High-Precision NIR Spectroscopy Steve Osterman1, John Bally1, Scott Diddams2, Frank Quinlan2, Gabriel Ycas2,3 1University of Colorado, Center for Astrophysics and Space Astronomy, Boulder, CO 2National Institute for Sciencde and Technology, Time and Frequency Division, Boulder, CO 3University of Colorado, Department of Physics, Boulder, CO
Abstract HARPS, HIRES, etc. have shown the value of high precision spectroscopy for RV planet searches at visible We have developed a broad-band laser frequency comb at NIST to support high-precision H-Band wavelengths, but visible light RV planet searches are best suited to to solar like stars, making detection of spectroscopy at resolutions of 50,000 and higher. We present an overview of laser frequency comb an earth-analog extremely challenging. Alternatively, low mass M Dwarfs are promising subjects but are not technology and detailed capabilities of the existing H-band laser frequency comb. In addition to ground-based
J easily observed at visible wavelengths. Precision NIR spectroscopy is becoming a reality with advances in applications, we will discuss the possibility of performing high-precision spectroscopy from the SOFIA aircraft. laser comb technology, making high precision RV studies of low mass stars a possibility.
Why look for planets around low mass The Laser Frequency Comb as a High The CU/NIST H-Band Laser Comb stars? Precision Wavelength Reference: ! 250 MHz Er fiber comb (0.002nm/mode at 1550nm) ! Larger RV signature for a given planet mass in the habitable zone ! Two levels of mode filtering increase spacing to 12.5GHz (0.11nm/ ! An LFC represents an ideal wavelength standard: ! Lower mass " Lower temperature mode, or !/"!=15,500 at 1550nm) w/ > 50nm band width ! Dense array of uniformly spaced, uniformly bright lines ! Habitable zone is closer to the host, increasing RV signature ! Post filter non-linear broadening increases band width to 400nm ! Lower host mass increases RV signature ! Frequencies traceable to a fundamental standard. ! Nearest neighbor suppression = 20-40dB for broadened spectrum ! Tighter orbit leads to shorter period (weeks) ! Precision and long term stability should exceed the ultimate precision ~30 dB suppression, ! Large number of host stars within 10pc of the spectrograph. HOSM, SMA present ! Cool stars brighter in the NIR ! A laser Frequency Comb meets these requirements: ! No shortage of narrow spectral features ! The LFC creates a high precision optical frequency ruler: Each line (mode) can be written as fn = nfr + f0 P]":45?97>3;"H:"S7;FF93".9::""
%#!" %!!" "'979"<3BC"%&'()*":>3H;A" $#!" H9F>;:"2\9?"%!!_8":6BI4?5" $!!" Quinlan, 2010 (arXiv:1002.4354) M3;YGBC4?9?@;"B<"@F9::"." #!" :793:"I4764?"$!"M@J" Low power High power !" 12.5GHz filter cavity filter cavity /" +" 0" 1" -" )" *" ," (" f:2f mode ." HNLF &'" locking 2345678"/9:;3"<3;=>;?@A"@BCD"<>?@EB?4?5"9:"DB76"9":4C>F79?;B>:"9?G"BH;3F94G"I9H;F;?576" What else could be done if high precision 3;<;3;?@;J""06;"F9:;3"@BCD"4:"I;FF":>47;G"