Generation and versatile transmission properties of ring-shaped beams based on thermal lens effect of magnetic fluids and ring-limited windows

A simple method is proposed to generate ring-shaped beams via combining thermal lens effect of magnetic fluids and placement of ring-limited windows behind magnetic fluid samples. Far-field patterns of ring-shaped beams are simulated after the ring-limited windows. The relationship between the system parameters and the transmission parameters (describing the transmission properties of the system) are calculated and analyzed in detail. The results show that each transmission parameter is almost independent of one of the system parameters. The influence of magnetic fluid characteristic parameter on the transmission properties is also investigated. The results presented in this work may be very helpful for designing optical devices with high repeatability of performance for specific applications, such as power-tunable optical switch, optical attenuator and modulation depth amplifier.