Simple Laser-Light Modulator with Acrylic Plate Faraday Rotator for Educational Use

He-Ne and other gas lasers, which were once expected to become the major tools of optical communications in the future, now seem to be very far from practical application in communications technology. But the beauty and excellent rectilinear propagation of a gas laser is very moving, and it is still attractive as an educational material in optical communications. The author constructed a simple optical communication system using a He-Ne gas laser for educational use. In this system, a commercially available acryl plate (cut to square bar, 10 × 10 × 20 mm in size) was used as the Faraday rotator to modulate the laser beam, because it is easy to process, highly transparent, lightweight, and easy to obtain.