Microfluidics enables the formation of femto- to picoliter-sized droplets, which have garnered attention for their potential applications as optical components. Their unique features, such as uniformity, periodicity, and self-assembly, make them particularly suitable for optical gratings. This chapter focuses on optofluidic grating including diffraction grating and long-period grating using microfluidic droplets. The discussion covers the working principle, droplet formation, relationship between the optical signals (diffraction or transmission) and the droplet grating characteristics.