Novel Wavelength Standards in the Near Infrared

Overview

The document is a final report titled "Novel Wavelength Standards in the Near IR," authored by Dr. Kristan L. Corwin from Kansas State University, covering the research period from May 1, 2005, to October 31, 2007. The primary objective of the research was to develop a new class of portable optical frequency references utilizing sub-Doppler spectroscopy within gas-filled hollow-core photonic bandgap (PBG) optical fibers.

The report outlines three major components of the research:

1. Spectroscopy in Hollow Fiber: The study successfully observed sub-Doppler spectra for the first time in hollow-core fibers. It established a relationship between the feature width of the spectra and the diameter of the fiber core, which is crucial for optimizing the performance of these optical systems.

2. Development of a Near-IR Optical Frequency Comb: A mode-locked chromium-doped forsterite laser was stabilized as an optical frequency comb for the first time, employing prism pair dispersion compensation. This advancement allowed for the characterization of molecular transitions within the hollow fibers, revealing unique noise properties that enhance the precision of measurements.

3. Sealing Fibers with Molecular Gases: The research included efforts to seal the hollow-core fibers filled with molecular gases, aiming to create portable frequency references. This aspect is significant for practical applications, as it addresses the challenges of maintaining the integrity and performance of the optical fibers in various environments.

The report also discusses the broader context of frequency metrology, highlighting advancements in portable standards created by the National Institute of Standards and Technology (NIST) and other international institutions. These standards have moderate uncertainties and are essential for commercial applications. The document emphasizes the advantages of using hollow-core PBG fibers, which allow for high-intensity light confinement with low loss, making them superior to traditional capillary fibers.

Overall, the research contributes to the field of optical frequency references by demonstrating the feasibility of using hollow-core PBG fibers for high-accuracy infrared spectroscopy. The findings have implications for the development of portable optical devices, enhancing the precision and accessibility of wavelength standards in the near-infrared region. The report concludes with a recognition of the transformative impact of frequency comb technology and hollow fiber technology on the science of frequency metrology.