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NIST Measurement Services: Measurement Assurance Program for the Spectral Density of Relative Intensity Noise of Optical Fiber Sources Near 1550 nm



Gregory E. Obarski, Jolene Splett


This paper provides the documentation to establish a measurement assurance program (MAP) for the spectral density of relative intensity noise (RIN) of optical sources. A standard is made available to industry for high-precision calibration of RIN measurement systems. The device is an erbium-doped fiber amplifier (EDFA) to which is coupled a linear polarizer followed by a narrow pass-band optical filter. Measurements show that the spectral density of the RIN is invariant under attenuation and pump current, and constant from zero t many tens of gigahertz. These properties render it suitable as a standard for the calibration of high-speed systems. We characterize the device for use as a standard in the 1550 nm wavelength range over a radio-frequency (rf) baseband of 0.1 GHz to 1.1 GHz. For the typical device studied in depth, the magnitude of the RIN is -109.9 dB/Hz with uncertainty < or =} 0.12 dB over the entire bandwidth. Since the behavior of the RIN standard can be determined from physical theory, we give a thorough derivation of the spectral density of RIN in the frequency representation. This derivation has been absent from the literature. We use this derivation to formulate the needed numerical RIN equations in spatial wavelength coordinates that are used to determine the RIN from optical power spectral density measurements made with a calibrated optical spectrum analyzer. The standard is then applied to calibrate a NIST RIN measurement system. To further validate the standard we develop a second calibration method based on a distributed-feedback (DFB) laser having Poisson-limited RIN. We apply each method to determine the frequency-dependent calibration function (Κ) of our RIN system and derive the equation that relates them. A comparison of the calibration functions obtained from measurements using the two methods agrees well with the theory developed.
Special Publication (NIST SP) - 250-57
Report Number


calibration, measurement assurance, optical fiber sources, Poisson-limited laser, relative intensity noise, spectral density, transfer standard


Obarski, G. and Splett, J. (2000), NIST Measurement Services: Measurement Assurance Program for the Spectral Density of Relative Intensity Noise of Optical Fiber Sources Near 1550 nm, Special Publication (NIST SP), National Institute of Standards and Technology, Gaithersburg, MD, [online],, (Accessed April 15, 2024)
Created August 31, 2000, Updated October 12, 2021