system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Single wavelength light is emitted by:
assistant
The correct answer is  Argon laser light has wavelength of 470 nm which is monochromatic (single wavelength or frequency) in nature. 
It produces an intensity of 200 to 300 mW.

​Ref: Textbook of Operative Dentistry, Nisha and Amit Garg, 3rd edition, Pg no:277