Final answer:
A laser beam can travel down an optical fiber due to the principle of total internal reflection, along with optical fibers having low loss, high bandwidth, and reduced crosstalk.
Step-by-step explanation:
The property of light that allows a laser beam to travel down an optical fiber is the principle of total internal reflection. Optical fibers are designed to be highly transparent, which enables light to travel long distances with minimal loss of intensity. This characteristic, known as low loss, is critical for efficient optical communication. Additionally, light from lasers has high bandwidth, which allows more data to be transmitted over a single fiber compared to electrical signals on a conductor. Another advantage is reduced crosstalk, meaning optical signals in one fiber do not interfere with those in adjacent fibers. Together, these properties enable optical fibers to be an effective medium for transmitting laser signals for telecommunications and Internet communications.