High Q/V (quality factor/mode volume) platforms enable simultaneous localization of light in space and time and have enabled enhanced performance metrics in applications such as optical signal processing, photovoltaics, optical sensing and optical trapping. Slotted photonic crystal nanobeams (SPCNs) are one type of high Q/V structure that support mechanical modes in addition to high Q optical modes, opening the door to favorable optomechanical properties. In this work, in-plane excitation of fundamental resonance modes in SPCNs with high optical quality factor and high values of optomechanical coupling strength is investigated towards the realization of a monolithic configuration that is compatible with photonic integrated chips. In-line and side- coupled excitation configurations are studied. Simulations suggest that the number of optical modes supported in the SPCNs and the transmission intensity of light in these modes depend strongly on coupling configuration. For high Q SPCNs, in-line coupling suppresses the fundamental optical mode. Side-coupling supports excitation of the fundamental optical mode, but suppresses even order modes in the cavity.
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