A spectroscopy system is described. The spectroscopy system includes a cell, a photodiode, and mirrors. The cell has walls forming a chamber therein. The chamber is configured to receive laser signal(s) and retaining a vapor therein. The vapor fluoresces in response to the laser signal(s). The mirrors are configured to direct fluorescent light from the vapor toward the photodiode. In some embodiments, the spectroscopy system is incorporated with a photonic integrated circuit.

A system and method for detecting and quantifying the concentration of rare earth elements in a fluid contacting a sensor, the method having the steps of: providing the sensor to an environment such that the sensor is in contact with the fluid, wherein the sensor features a fiber extending between a first end and a second end along a longitudinal axis, wherein the sensor further features a coating on the second end of the fiber, and wherein the coating is a metal-organic framework material including, but not limited to zinc adeninate, 1,3,5-benzenetricarboxylate, 4,4-biphenyldicarboxylate, and combinations thereof; interrogating the sensor with light; collecting a luminescent signal; and detecting the rare earth elements in the fluid contacting the sensor using the luminescent signal.