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Tuning the wavelength of a colorless laser transmitter, used to build an upstream channel in the WDM-PON transport domain of a 5G mobile radio access network, to the wavelength of the maximum transmission of its multiplexer channel is implemented by a number of regulated and proactive procedures. Part I is a beginning of this article and is devoted to straight initialization. The main attention in the article will be paid to the consideration of reflective type systems. Broadband and single-frequency reflective methods for tuning direct modulation lasers: VSCEL, DFB, DBR, and external modulation lasers: integral module on InP-substrate, with direct detection and heterodyne reception are analyzed, their advantages and disadvantages are determined. The transition to modulation reflectometric methods of tuning on few close frequencies is substantiated, for which two- and three- frequency technologies for multiplexer probing based on EML lasers with scanning are proposed. The use of methods makes it possible to increase the signal-to-noise ratio, sensitivity and accuracy of multiplexer spectral characteristics measurements, and, consequently, the accuracy of tuning the wavelength of a colorless laser transmitter to the central wavelength of one of multiplexer channels.
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