  Here we show that mesoscale freezing water droplet with low Bond number can
behave as fully biocompatible natural microlenses to form the photonic hook in
application to tunable optical switch. We first introduce and demonstrated the
basic concepts of all-optical switch without changes in the wavelength of
illumination of a particle or any moving parts involved. The principle of
operation of the switch based on the temperature-induced phase change inside
water droplet refractive index. Simulation shows that the optical isolation of
switched channels for an optical switch with linear dimensions of about
15{\lambda}3, based on freezing water droplet, can reach 10 dB during the
temperature variation at fixed wavelength. The freezing mesoscale droplets
acting as time domain photonic hook generator open the intriguing route for
full optical switching in a multifunctional green electronics tool for sensing,
integrated optics and optical computers.
