Optical cavity resonance width

This problem demonstrates the link between the widths of the cavity response and the transmission peaks of this well-known interferometer. However, the fringe pattern observed with a Fabry-Perot etalon should not be confused with the mode pattern of a laser having a plane-parallel resonator. The Fabry-Perot etalon is normally used with the plates so close together that all the transverse modes of the corresponding optical cavity are virtually degenerate in frequency. The plane wavefronts assumed in the discussion of the theory of the etalon are composed of an infinite sum over the transverse modes of the cavity. 

An embodiment having a cylindrical structure is shown above. The detector element is built on a substrate 24 of p-doped CdTe, CdMnTe, InSb or ZnTe. To facilitate the removal of holes, p+-type regions 30, 30 are embedded in the layer 7. A resonant cavity structure is also provided. The width of the layers 7, 16 and 24 combine to equal one-quarter of the wavelength of the frequency of energy the detector is designed to receive. These layers form a resonating function not unlike the concept of resonating cavities used in optics. 

Optical pumped UV lasing spectrum of ZnO film was observed as shown in figure 5. The samples were optically pumped by a frequency-tripled mode-locked Nd YAG laser 355nm, lOHz repetition rate, 15ps pulse width. The pump beam was focused to a spot with diameter of about 20 pm on the surface of ZnO film. The threshold of lasing was as low as 0.24 pJ. From the lasing spectrum, we could find that much narrow lasing peak with line-width less than 0.6nm. This was due to self-formed resonator cavities [14]. 

The quantity may be written in terms of the circuit parameters of Fig. 5 as Qu = (oL/Ru- The inductance of the cavity may be found by calculating the flux passing through a strip normal to the E field and the optical axis in the resonator of width A/2, multiplying by the mode number q, and dividing by the current flowing in the cavity =... 

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