This document presents the core chapters of a doctoral thesis developing a co-programmable platform for continuous-wave nonlinear mid-infrared vibrational spectroscopy. Conventionally, nonlinear vibrational spectroscopies such as sum- and difference-frequency generation (SFG/DFG) provide interface-specific chemical fingerprints, yet in practice they remain strongly instrument-defined: spectral access, stability, and reproducibility are tightly coupled to ultrafast sources, synchronization, and phase-matching pipelines. This work defines and demonstrates a co-programmable platform that reorganizes nonlinear vibrational readout at the level of a deployable spectroscopy pixel. A pixel is a dual-band nanocavity that co-couples visible and mid-infrared (MIR) fields at a single site, enabling MIR-addressed excitation while emitting narrow nonlinear lines in the visible for straightforward detection. Here the pixel is implemented as a dual-resonant nanoparticle-on-slit nanocavity hosting molecules in a nanogap hotspot.

Broadband operation is obtained without broadband ultrafast pulses: a tunable continuous-wave MIR source is swept across selected windows while the visible pump and detection chain remain fixed. Source--structure co-programming uses post-fabrication FTIR resonance maps to choose MIR sweep windows that overlap the measured enhancement landscape of each chip, turning device variability into an instance-specific scheduling choice rather than a change of measurement class. The output is a standardized vibrational fingerprint expressed as MIR-indexed, co-registered nonlinear spectra (vSFG and vDFG, with optional additional mixing channels) and drift-robust observables such as power-normalized spectra and ratiometric traces. An effective-susceptibility description captures interference between resonant vibrational terms and a complex non-resonant background, enabling consistent fitting and comparison across devices and molecules.