Laser Wavelength Metrology

Modern fiberoptic networks use Dense Wavelength Division Multiplexing (DWDM) to pack many information channels on a single fiber, using closely spaced laser wavelengths. It is essential to have absolute wavelength standards and calibration instruments to maintain the network. In the future, much tighter control will be needed as channel capacity is expanded to Ultra DWDM.

Our laboratory has developed a laser wavelength measuring instrument that can make absolute measurements to an accuracy of 1.5 parts in 10⁹. It employs a Michelson interferometer to make a ‘rough’ measurement to better than 1 in 10⁷, and a Fabry-Pérot interferometer to make the final measurement. The reference laser is an iodine-stabilized HeNe laser with 1 in 10¹¹ accuracy.

Using our wavelength meter, we have established a set of absolute standards throughout the blue region of the spectrum (420–465 nm), using saturated absorption in the ¹³⁰Te₂ molecule.

The wavelength meter is capable of working at any wavelength in the visible and near infrared. With a different diode-array detector, it can be used to establish standards in the 1.3 and 1.5 micron telecommunication bands.

Selected Publications:

T. J. Scholl, S. J. Rehse, R. A. Holt, and S. D. Rosner, “Broadband precision wavelength meter based on a stepping Fabry-Pérot interferometer,” Review of Scientific Instruments 75, 3318-3326 (2004). pdf

T. J. Scholl, S. J. Rehse, R. A. Holt, and S. D. Rosner, “Absolute wave-number measurements in ¹³⁰Te₂: reference lines spanning the 420.9-464.6-nm region,” Journal of the Optical Society of America B 22, 1128-1133 (2005). pdf