Laser-actuated optofluidic diaphragm capable of optical signal tracking

We present a laser-actuated adaptive optical diaphragm that is capable of aligning the disturbance of the coaxiality of the optical signal and the plane of aperture. The diaphragm consists of two layers of immiscible liquids, where the bottom layer absorbs a pumping laser beam and transmits an optical signal, while the upper layer transmits the pumping laser beam and stops the optical signal. The operating principle is based on creating the circular thermocapillary rupture of the upper layer by Marangoni forces induced by heating with the pumping laser beam. The thermocapillary rupture serves as an aperture of the diaphragm. The aperture diameter at a fixed power of the laser beam depends on the upper layer thickness and reaches diameters up to two times larger in comparison with diaphragms operating on electrowetting and dielectrophoresis. The aperture tuning ratio is 100%. By shifting the pumping laser beam in the plane of the diaphragm, the aperture can be displaced for a distance up to a few of its radii.We present a laser-actuated adaptive optical diaphragm that is capable of aligning the disturbance of the coaxiality of the optical signal and the plane of aperture. The diaphragm consists of two layers of immiscible liquids, where the bottom layer absorbs a pumping laser beam and transmits an optical signal, while the upper layer transmits the pumping laser beam and stops the optical signal. The operating principle is based on creating the circular thermocapillary rupture of the upper layer by Marangoni forces induced by heating with the pumping laser beam. The thermocapillary rupture serves as an aperture of the diaphragm. The aperture diameter at a fixed power of the laser beam depends on the upper layer thickness and reaches diameters up to two times larger in comparison with diaphragms operating on electrowetting and dielectrophoresis. The aperture tuning ratio is 100%. By shifting the pumping laser beam in the plane of the diaphragm, the aperture can be displaced for a distance up to a few of its radii.