A versatile wide-spectrum photonic integrated circuit (PIC) platform, spanning from ultraviolet (UV) to infrared (IR) wavelengths, is essential for advancing on-chip optical microscopy and spectroscopy applications. The key desirable requirements for PICs are low-loss, low-autofluorescence background signals, and high-refractive index contrast (HIC) to enable compact designs. Here, we present a low-loss, low-autofluorescence aluminum oxide (Al2O3) waveguide platform developed using atomic layer deposition (ALD). At 405 nm, the Al2O3 strip waveguide exhibits an autofluorescence background approximately 200 times lower than silicon nitride (Si3N4) and a propagation loss of less than 0.5 dB/cm. We demonstrate the suitability of the Al2O3 platform for multicolor on-chip total internal reflection fluorescence (TIRF) and super-resolution optical microscopy. The proposed Al2O3 platform offers a promising solution for highly sensitive on-chip bioimaging and spectroscopy applications.