Standards Development

Scope

Optical frequency standard is a type of atomic frequency standard using atomic(ion) transitions in the optical band as stable frequency references. Generation of accurate and precision optical frequency is the intrinsic capability of optical frequency standards. In order to character the frequency of an optical standard, many different parameters are adopted. These parameters have very similar names, but differ a lot in the numerical numbers. For example, time-interleaved self-comparison frequency instability versus independent clock output frequency instability(both represented in Allan deviation), absolute frequency uncertainty versus systematic frequency shift uncertainty(both called uncertainty).

The scope of this working item is to specify important parameters that characterize the frequencies of optical frequency standards

 - The definition of different types of frequency instabilities, their standard measurement methods and the expected scenarios where they could be used.

- The definition of different types of frequency uncertainties, and the evaluation or measurement methods.

The scope excludes:

- The characterization of the optical frequency standard other than frequency

 - Protocols of how the frequency is output from the optical frequency standard

This standard is applicable to the performance evaluation in the process of optical frequency standard research, product development, test and calibration. This standard will be a good reference for the manufactures to choose which parameters they would like to specify and for the users to find out which parameter is suitable for their applications.

Purpose

Frequency character is the most important parameter of optical frequency standards. There are many different types of frequency uncertainties and instabilities of optical frequency standards that have different definitions and applications. These parameters have very similar names but differ significantly in numerical values, which causes ambiguities and misunderstanding. The development and marketing of optical frequency standards are going to flourish because of the upcoming redefinition of the SI time unit, the second. An international standard is expected to guide the development and application of optical frequency standards.

The standard is applicable to the performance evaluation in the process of optical frequency standard research, product development, test and calibration. The standard will be a good reference for optical frequency standard manufactures to choose which parameters they would like to specify and for the users to find out which parameters are suitable for their applications.