A system for suppressing optical noise within an optical spectroscopy analyzer for probing a fluid, comprising a substantially hermetically sealed compartment adapted to contain the fluid, the compartment containing a light source, a first optical member and a second optical member, and allowing measurement of the intensity of light propagating through the second optical member, the first optical member being between the light source and the second optical member, the compartment allowing light from the light source to propagate through the first and second optical members (540, 550) and the fluid on different optical paths (210, 220), the different optical paths (210, 220) having different optical distances between the light source and the first optical member, between the first optical member and the second optical member, or between the light source and the second optical member, the system further comprising: means (130, 410, 580, 620a, 620b, 620c) configured for periodically modifying a stimulus to periodically vary between lower and upper magnitudes of the stimulus to generate a periodically modified stimulus, and applying the periodically modified stimulus to the fluid for modifying a refractive index of the fluid, characterized by further comprising: an inlet conduit providing a first fluidic pathway for permitting injection of the fluid into the compartment; an outlet conduit providing a second fluidic pathway for the fluid, wherein the means (130, 410, 580, 620a, 620b, 620c) for periodically modifying the stimulus comprises a timer and a modulating valve directly and/or fluidically coupled to the outlet conduit, the timer being configured to regulate electronically and/or mechanically an operation of an open-shut cycle of the modulating valve, the modulating valve being configured to receive the fluid from the compartment via the outlet conduit, the modulating valve further being configured to produce a substantially periodic variation of a pressure of the fluid contained in the compartment for modulating as a function of time a time-dependent pressure applied to the fluid as the periodically modified stimulus, the system thereby permitting to average multiple measurements of an intensity of lights that have propagated through the different optical paths (210, 220) over an interval greater than a period for the stimulus to vary from the lower magnitude to the upper magnitude, in order to mitigate optical noise due to interference between light propagating through the different optical paths (210,220). means (130, 410, 580, 620a, 620b, 620c) configured for periodically modifying a stimulus to periodically vary between lower and upper magnitudes of the stimulus to generate a periodically modified stimulus, and applying the periodically modified stimulus to the fluid for modifying a refractive index of the fluid, characterized by further comprising: an inlet conduit providing a first fluidic pathway for permitting injection of the fluid into the compartment; an outlet conduit providing a second fluidic pathway for the fluid, wherein the means (130, 410, 580, 620a, 620b, 620c) for periodically modifying the stimulus comprises a timer and a modulating valve directly and/or fluidically coupled to the outlet conduit, the timer being configured to regulate electronically and/or mechanically an operation of an open-shut cycle of the modulating valve, the modulating valve being configured to receive the fluid from the compartment via the outlet conduit, the modulating valve further being configured to produce a substantially periodic variation of a pressure of the fluid contained in the compartment for modulating as a function of time a time-dependent pressure applied to the fluid as the periodically modified stimulus, the system thereby permitting to average multiple measurements of an intensity of lights that have propagated through the different optical paths (210, 220) over an interval greater than a period for the stimulus to vary from the lower magnitude to the upper magnitude, in order to mitigate optical noise due to interference between light propagating through the different optical paths (210,220). an inlet conduit providing a first fluidic pathway for permitting injection of the fluid into the compartment; an outlet conduit providing a second fluidic pathway for the fluid, wherein the means (130, 410, 580, 620a, 620b, 620c) for periodically modifying the stimulus comprises a timer and a modulating valve directly and/or fluidically coupled to the outlet conduit, the timer being configured to regulate electronically and/or mechanically an operation of an open-shut cycle of the modulating valve, the modulating valve being configured to receive the fluid from the compartment via the outlet conduit, the modulating valve further being configured to produce a substantially periodic variation of a pressure of the fluid contained in the compartment for modulating as a function of time a time-dependent pressure applied to the fluid as the periodically modified stimulus, the system thereby permitting to average multiple measurements of an intensity of lights that have propagated through the different optical paths (210, 220) over an interval greater than a period for the stimulus to vary from the lower magnitude to the upper magnitude, in order to mitigate optical noise due to interference between light propagating through the different optical paths (210,220).