A laser printer uses the technology of a semiconductor laser. Let`s break down all the options:

Option 1: Dye lasers are typically used in applications like spectroscopy where versatile wavelength selection is required. They are not suitable for printing processes.

Option 2: Gas lasers, like helium-neon lasers or carbon dioxide lasers, are commonly used for applications that require powerful and constant light beams, such as cutting metal or performing delicate eye surgery.

Option 3: Semiconductor lasers, also known as laser diodes, are used in a range of technology including CD and DVD players and fiber optic communication, as well as in laser printers. They`re suitable due to their ability to emit a narrowly-focused light beam essential for precise printing.

Option 4: Excimer lasers are used in applications including eye surgery or micro-machining, not in printing.

This makes the third option, `Semiconductor laser`, the correct answer for this question since it`s the type of laser most commonly used in laser printers.