Light matter interaction holds significant relevance across a range of applications including lasing, sensing, communications, and computing. One prominent method for modulating optical properties is through the use of a Fabry-Perot cavity, which controls the photonic density of states within optical cavities. Additionally, plasmonic and high contrast dielectric cavities represent a cutting-edge approach for photonic dispersion engineering and phase modulation. These techniques confine light field distribution within nanostructures whose dimensions are comparable to, or smaller than, the light wavelength. Materials exhibiting resonant quantum confined states, such as excitons, phonons, and magnons, offer alternate avenues for manipulating light propagation and interaction. Our work aims to explore light-matter interactions within various innovative low-dimensional semiconductors. This exploration is achieved by generating cavity photons either out-of-plane (Fabry-Perot cavity) or in-plane (plasmonic or dielectric cavity), offering a substantial platform for extensive degrees of freedom in optical enhancement and tunability. Van der Waals (vdW) layered semiconductors often manifest strongly bound exciton states at room temperature. Many also exhibit emergent physical and quantum phenomena such as spin-ordering and charge density wave transitions which are of great promise for both electronics and photonic applications. In this thesis, I will show that multilayer transition metal dichalcogenides (TMDCs) by themselves provide an interesting platform for excitation and control of excitonic modes, paving the way to exciton-photonics without the need of external cavity media. As a result, by nanoscale patterning of such excitonic 2D chalcogenides into nanoresonators with sizes comparable to the light wavelength range, it is possible to demonstrate a light-matter interaction among excitons, plasmons, and dielectric cavities and thus the formation of hybrid exciton-cavity-plasmonic quasiparticles. This hybridization represented by optical reflectance response can be tuned as a function of nanostructure dimensions. Further, we show that the strong interaction among the three-oscillator system gives rise to a Rabi splitting exceeding 410 meV and a strong suppression of the absorption resonance. This potentially paves the way to exploring the interaction between quantum emitters and exciton-polariton condensation. I will also show observation and manipulation of optical properties of vdW magnetic semiconductors by optical cavities, particularly antiferromagnetic semiconductors such as MPX$_3$ (M = Fe, Ni, Mn; X = S, Se). The recent emergence of vdW magnetic semiconductors provides a new platform to explore the coupling of fundamental spin phenomena with optical resonances, due to the persistence of long-range magnetic orders. Such spin-induced optical properties include high linear dichroism contrast, non-linear optical response, and spin-induced exciton formation, etc. However, while ferromagnetism in vdW crystals is easily detected, antiferromagnetism is much more difficult to probe due to the lack of net magnetic moment. We have identified ways to detect the antiferromagnetism in various antiferromagnets. For example, we are able to image the AFM-zigzag order in FePS$_3$ by using optical linear dichroism (LD). We also demonstrate the spin orientation imaging in MnPSe$_3$ by using non-linear optical methods as second harmonic generation (SHG) mapping. All of these methods are based on the strong coupling between the magnetic order in the lattice and the optical response (linear or non-linear) to light polarization. Further, the spin-induced LD and SHG can be tuned by external stimuli, such as magnetic field and strain, as well as some internal manipulation, such as the control of the cavity sizes and metastructures. This paves the way for tuning spin orientations by the artificial design of meta-surfaces, paving a new path towards tunable and integrated magneto-photonics.