Lambdameter for accurate stability measurements of optical transmitters

Abstract

To accurately measure wavelengths of 1.3 and 1.5 micrometers single-mode sources, we developed a lambdameter that can be used in the near IR and the red regions of the spectrum. Wavelength accuracy and resolution are approximately equals 0.1 ppm (parts per million) at 0.633 micrometers . They were measured by comparing each of two adjacent modes of a HeNe laser, frequency- stabilized by a polarization technique, with a single mode from a second frequency-stabilized HeNe laser. We also verified the wavelength of the reference laser with an accuracy of 1 ppm by comparing it with the 1.52 micrometers HeNe laser line. The uncertainty in wavelength of the 1.52 micrometers HeNe laser is limited to the width of the Doppler gain curve, whose peak is known within 0.2 ppm. We describe our lambdameter and the performance of its reference laser as a wavelength transfer standard. Measurements on a commercially packaged 1.52 micrometers distributed-feedback (DBF) laser diode transmitter show that its wavelength fluctuates by at least 1 ppm during normal changes in room temperature.