Department News

KAIST researchers developed an ultrastable optical frequency comb stabilization technique

관리자 2020.04.07

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Frequency-stabilized optical frequency combs have created many high-precision applications. Accurate timing, ultra-low phase noise, and narrow linewidth are prerequisites for achieving the ultimate performance of comb-based systems. Ultra-stable cavity-based comb-noise stabilization methods have enabled frequency instability to the sub-10-15-level frequency instability. However, such state-of-the-art methods are highly complex and alignment-sensitive, and their use has been mostly confined to advanced metrology laboratories. Here we have established a simple, compact, alignment-free, and potentially low-cost all-fiber photonics-based platform for generating multiple ultra-stable optical frequency combs. The achieved performance includes 1-fs timing jitter, 10-15-level frequency instability, and <5-Hz linewidth, rivalling those of cavity-stabilized combs. This method features flexibility in configuration: as a representative example, two combs were stabilized with 180-Hz repetition rate difference and ~1-Hz relative linewidth and could be used as an ultra-stable, octave-spanning all-fiber dual-comb spectroscopy source. The demonstrated method constitutes a mechanically robust and reconfigurable tool for generating multiple ultra-stable combs that are highly suitable for various high-precision field applications.