Flagship D

Silicon chip frequency comb and light sources

Frequency combs combined with atomic or molecular clocks constitute the most accurate measurements devices in science. Such instruments may reach instabilities at the fractional uncertainty level of 10-18. This corresponds to a clock stability in which the clock losses about half second on the lifetime of the Universe. Frequency combs is a versatile laser device which provides a rain bow spectra of discrete equidistant spaced lines in frequency that may be applied to a number of precision tasks such as: high speed optical communications, search for time drift of fundamental constants, detection of gravitational waves, mapping of the Earth’s gravitational potential, precision geodesy, etc. The typical foot print of commercially available frequency combs is several square meters and come at the cost of about half a million Euros. To make frequency combs available to a broad community at low cost, low footprint, yet robust and versatile we have initiated an important technological development of micro sized frequency combs referenced to stable optical laser sources. These so-called integrated silicon chip combs are compact, robust and potentially transportable in the field. However, unlike bulky conventional combs, silicon combs suffer from unwanted phase and frequency noise limiting its applications. In addition, these sources suffer from thermal instabilities as a result of the pumping producing the comb structure. To overcome these challenges we plan to employ a number of strategies. We will reduce phase and frequency noise by referencing the comb to an ultrastable laser source. We will work on novel comb designs based on advanced materials such as AlGaAs where the threshold power is significantly lower compared conventional systems. Integrate a genuine lock scheme that ensures the micro resonator resonance is locked to the pump laser.

Flagship Leader

Jan Westenkær Thomsen
Niels Bohr Institute
+45 51 68 04 10
18 APRIL 2021