Real-time phase tracking for wide-band optical frequency measurements at the 20th decimal place

High-Speed Random-Channel Cryptography in Multimode Fibers

“…For practical deployment, independent, frequency-locked lasers should be used at Alice and Bob [28]. There are a range of remote laser frequency-locking techniques that Alice and Bob can implement, including injection locking, locking to external references, and direct measurements [39][40][41]. Optical circulators (OC) were used to separate the outgoing and incoming light at the transceivers.…”

The Quantum Technology Puzzle Game

“…Therefore, the comb itself has two purposes: it acts as a reference for all the lasers to maintain their narrow linewidth, and it is the clockwork that transfers the optical frequency's spectral purity to the microwave region, or to a different optical frequency. The latter is needed when comparing a strontium lattice clock to other optical atomic clocks such as ytterbium lattice clocks (578 nm), calcium ion clocks (729 nm), and many others [4]. It is also needed to transfer the low phase noise of visible wavelengths to the telecommunication range at 1.55 µm, at which long-distance transfer of the frequencies via an optical fiber becomes possible.…”

Fiber-delay-line-referenced optical frequency combs: three stabilization schemes

“…Optical frequency combs (OFCs) emit optical pulse trains with millions of well-defined, mutually coherent, perfectly spaced comb modes [1][2][3][4][5][6][7] . This unique feature enables coherent phase linking among the optical, microwave, and terahertz regimes [8][9][10] . More importantly, the development of low-noise OFCs over the past two decades has experienced fascinating evolution, which facilitates advances of various applications such as ultra-low-noise microwave generation [11] , distance ranging [12][13][14] , and dual-comb spectroscopy [15,16] .…”