NIST's Time and Frequency Metrology Group, in collaboration with other groups from the Time and Frequency and Optoelectronic Divisions, were recently awarded funding from NIST's Innovations in Measurement Science (IMS) program to pursue research aimed at improving timing metrology by a factor of 1,000 to enable current and future technological innovations.
This five-year project aims to produce much more accurate and precise noise measurements (improvements of a factor of 1,000 or more) than currently available, to expand the useful frequency range up to about 1013 Hz (a factor of about 100 in frequency range), and to provide precision noise metrology for "real world" operating conditions (environments with significant vibration, acceleration, and electromagnetic interference). Applications benefiting from substantially improved state-of-the-art noise metrology can be found in many areas, including homeland security, defense, and commerce.
The proposed plan combines ultrastable lasers, which already have been developed by NIST for optical atomic clock research, with femtosecond laser frequency combs to generate microwave to terahertz signals with ultralow noise that could not be directly produced. The breakthrough idea is the development of femtosecond laser frequency combs which can translate the extremely low noise of cavity-stabilized lasers to the much lower frequencies of the microwave and terahertz regions. This frequency division can bring the extremely low timing jitter and spectral purity of optical signals at about 1015 Hz into the 109 Hz to 1013 Hz spectral region of interest for electronic, microwave, and terahertz systems.
In addition to exploiting NIST expertise in stable laser oscillators and frequency comb science, this work will also lead to improvements in fast digital signal processing, improved laser stabilization technologies for a variety of applications, and novel hardware for vibration and acceleration testing. These improvements will directly benefit the project's goal of improving phase noise metrology and will also benefit other NIST missions, such as developing and measuring new ultra-high performance optical atomic clocks.