High finess cavity|SIMTRUM Photonics Store

Principle

The working principle of an ultra-stable cavity lies in the process of tightly locking the frequency of a conventional laser to an ultra-stable optical reference cavity that is housed in an ultra-high vacuum (UHV) environment and temperature-regulated precisely at its zero expansion point. The core of this technology resides in selecting materials with a virtually zero coefficient of thermal expansion (e.g., Ultra-Low Expansion (ULE) glass) and precisely controlling their temperature at the zero expansion point; meanwhile, elaborate mechanical design is adopted to isolate external vibrations, thereby rendering the cavity length extremely stable.

Subsequently, the precise Pound-Drever-Hall (PDH) frequency locking technique is applied: a small modulation is imparted to the laser beam, the signal reflected from the cavity is detected, and an error signal that indicates the direction of frequency deviation is generated. This error signal is then used to implement real-time feedback control on the laser, forcing its frequency to align at all times with the inherent, ultra-stable resonant frequency of the cavity. Ultimately, the laser frequency is stabilized at the resonance peak of the optical resonant cavity, achieving an equally unparalleled level of stability.

Q: Can it be used outdoors?

A: Our ultra-stable cavities can be equipped with mechanical positioning and protection devices to enable a certain range of short-distance relocation, and are also suitable for outdoor operation.

Q: What is the maximum number of wavelengths that can be customized?

A: Ordinarily, 2 wavelengths are available for customization; the customization of 4 wavelengths can also be achieved with special structures and optical lenses.