Fig. 2: The mechanism to generate highly stable ultrasonic oscillation

Figure. 2 (a) In a laser, photons (quantum of light) are emitted when the electronic state of an atom changes from a high energy state to a low energy state. The emitted light is confined by two mirrors referred to as cavity to generate high-purity light. (b) On the other hand, when the beam oscillation changes from a high-energy oscillation state to low-energy oscillation state, it can also generate a high-purity ultrasonic vibration.