The invention provides a system for regenerative selective catalytic reduction including a catalyst chamber that contains a catalyst for reducing NOX in a gas stream passing therethrough. The phosphonates are obtained as reaction mixtures where the level of alkyl phosphonation is deliberately controlled to provide only partial alkyl phosphonation of the amino acid. Thereby, it is possible to realize a quantum cascade laser capable of preferably realizing reflectance control for light within a mid-infrared wavelength region on the laser device end face. One or more transmit power control commands are generated based on the comparison. Other device elements extend from the anchor.