NEW MEASUREMENT SERVICES FOR RELATIVE INTENSITY NOISE (RIN) OF LASERS.The demand for greater bandwidth in optical fiber communications has led to the development of laser transmitters and optical amplifiers with very low noise. The noise of a transmitter is often specified by its relative intensity noise Relative intensity noise (RIN), describes the instability in the power level of a laser. The noise term is important to describe lasers used in fiber-optic communication and LIDAR remote sensing. , or RIN. Because RIN can have a frequency dependence, the acronym RIN is used to denote the spectral density In statistical signal processing and physics, the spectral density, power spectral density, or energy spectral density is a positive real function of a frequency variable associated with a stationary stochastic process, or a deterministic function of time, which has of the relative intensity noise. To meet industry demands for precise measurement of RIN, a NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. scientist has developed a transfer standard for calibrating RIN measurement systems that employ electrical spectrum analyzers to resolve the spectral density of the RIN. The transfer standard is an erbium-doped fiber amplifier to which is coupled a linear polarizer polarizer an appliance for polarizing light. and a narrow-band optical filter ([less than]5 nm) centered in the 1550 nm wavelength range. The device is characterized for frequencies between 0.1 GHz and 1.1 GHz. The spectral density of the RIN, however, is stable and relatively constant to several tens of gigahertz, rendering it suitable for calibrations at even greater bandwidths. The RIN of the transfer standard is nominally -110 dB/Hz, with an uncertainty of [less than or equal to]0.12 dB/Hz. The invariance in·var·i·ant adj. 1. Not varying; constant. 2. Mathematics Unaffected by a designated operation, as a transformation of coordinates. n. An invariant quantity, function, configuration, or system. of the RIN under attenuation Loss of signal power in a transmission. Attenuation The reduction in level of a transmitted quantity as a function of a parameter, usually distance. It is applied mainly to acoustic or electromagnetic waves and is expressed as the ratio of power densities. yields considerable dynamic range with respect to radio-frequency (if) noise levels, and allows for the use of optical fiber connectors. The RIN of the transfer standard has been verified by a combination of theory and measurement, but it also has been confirmed using a laboratory RIN measurement system and a second RIN reference source. This new measurement service recently has been reviewed and certified as a formal calibration service as well as a measurement assurance program (MAP). Customers are offered the choice of using the transfer standard to calibrate To adjust or bring into balance. Scanners, CRTs and similar peripherals may require periodic adjustment. Unlike digital devices, the electronic components within these analog devices may change from their original specification. See color calibration and tweak. their own RIN system (a MAP), or they can send their own device to NIST for calibration. As an extension of this measurement service, the NIST scientist is developing a method for calibrating systems that measure the noise figure of optical amplifiers. |
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