We present a Mach-Zehnder-like interferometer capable of simultaneous superoctave (950 – 2100 nm) destructive interference with an intensity extinction of 4 × 10−4. Achromatic nulling is achieved by unbalancing the number of Fresnel reflections off ocular vibrational emission from the broadband, impulsive excitation and quantitatively examine the potential improvement in detectable concenptically denser media in the two interferometer arms. With a methane gas sample in one interferometer arm, we isolate the coherent moletration, compared to direct transmission geometry. The novel concept will benefit sensing applications requiring high detection sensitivity and dynamic range, including time-domain and frequency-domain spectroscopy.