Fiber laser-based frequency comb for frequency metrology in the infrared developed by NIST.NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. staff recently developed a phase-locked "frequency comb A frequency comb is it the graphic representation of the spectrum of a mode locked laser. An octave spanning comb can be used for a mapping radio frequencies into the optical frequency range or it can be used steer a piezoelectric mirror within a carrier envelope phase correcting " in the 1100 nm to 2200 nm wavelength region using fiber optic technology. This novel frequency comb should enable high-precision frequency metrology experiments in the near infrared and, in particular, across the telecommunications region of 1300 nm to 1600 nm. Indeed, over the past several years, stabilized frequency combs have revolutionized frequency metrology and optical clocks. However, prior to the present work, all self-referenced, phase-locked frequency combs used bulk-optic solid-state lasers A solid-state laser is a laser that uses a gain medium that is a solid, rather than a liquid such as in dye lasers or a gas as in gas lasers. Semiconductor-based lasers are also in the solid state, but are generally considered as a separate class from solid-state lasers (see and covered only the visible and very near infrared. This fiber laser-based comb comb 1. a vascular, red cutaneous structure attached in a sagittal plane to the dorsum of the skull of domestic fowl. It consists of a base attached to the skull, a central mass called the body, a backward projecting blade and upward projecting points. 2. extends this wavelength coverage 1000 nm further into the infrared. In addition, the fiber laser-based system can be much more compact, robust, power-efficient and lighter than a bulk optic solid state laser system, and can require less alignment. Finally, it can be integrated easily into a telecommunication system. The phase-locked frequency comb is based on a mode-locked, erbium-doped, fiber laser whose output is amplified and spectrally spec·tral adj. 1. Of or resembling a specter; ghostly. 2. Of, relating to, or produced by a spectrum. spec·tral broadened in novel dispersion-flattened, highly non-linear optical fiber to span from 1100 nm to 2200 nm. This super-continuum actually comprises a comb of frequency lines, separated by the laser repetition rate and with an arbitrary frequency offset. Borrowing the now standard techniques used with Ti:sapphire laser-based systems, researchers phase-locked both the comb spacing and offset to an RF oscillator oscillator Mechanical or electronic device that produces a back-and-forth periodic motion. A pendulum is a simple mechanical oscillator that swings with a constant amplitude, requiring the addition of energy at each swing only to compensate for the energy lost because of air . If the RF oscillator is phase-locked to an atomic frequency standard, the comb will form an accurate frequency ruler covering the entire near infrared region from 1100 nm to 2200 nm. Any unknown optical frequency then can be measured by simply comparing its frequency to that of the nearest tooth of the stabilized frequency comb. CONTACT: Nathan Newbury, (303) 497-4227; nnewbury@boulder.nist.gov. |
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