Thin Film Interference in Diamond Membranes for Control of Silicon Vacancy Center Emission

Abstract Thin‐film interference is widely leveraged in classical optics as a minimalistic yet powerful lever for controlling optical fields, underpinning technologies from anti‑reflective coatings to photovoltaics. However, extending this concept to diamond membranes and other thin film solid‐state quantum emitter host materials has remained unexplored, partly due to the challenges in fabricating ultrathin membranes. Here, a wedge‐shaped diamond membrane is engineered to demonstrate thickness‐dependent interference phenomena. This can not only be used as a broadband reflector or wavelength‐specific absorber, but it can also significantly modulate both excitation and emission intensities of silicon vacancy (SiV) centers, leading to a photoluminescence enhancement up to 96‐fold. This route circumvents the need for high‑Q cavities or intricate nanolithography, and the sample gradient offers a visualization of broadband resonances and anti‑resonances across the visible to near‑infrared spectrum. These findings offer an alternative method for controlling effective brightness enhancement or suppression of diamond color centers‐based quantum photonics. Beyond quantum emission enhancement, diamond membranes could serve as a passive layer such as a broadband reflector or a wavelength‐specific absorber, and find applications in heterostructures, photovoltaics, display technologies, and even in semiconductor thermal management.