Fabry- Perot resonator

The two examples shown demonstrate how an interference effect can be produced either by amplitude division of an incident beam, followed by retardation (achieved in this case by multiple reflection between the partially reflective parallel plates of a Fabry-Perot resonator) and recombination, or by division of the wave front at the multiple equally spaced slits of a diffraction grating, again followed by recombination. 

Experimental Techniques. A block diagram of the experimental set-up used for saturated absorption experiments is shown in Figure 1. The argon laser is a commercial 4W tube in a home made cavity. This cavity is made of three Invar rods, decoupled from the tube in order to avoid vibrations. Line selection is made with a prism, and single frequency operation is obtained with a Michel son interferometer. The laser can be frequency locked to a stable Fabry-Perot resonator with a double servo-loop acting on a fast PZT for line narrowing and on a galvo-plate for wide tuna-bility. This results in a linewidth of less than 10 KHz and a continuous tunability of 6 GHz. 

X. An Adjustable Finesse Fabry-Perot Resonator XL Optimization of Resonators XII. Summary... 

We have used the much simpler conical horn on our detector and Fabry-Perot resonator. We may estimate the ratio of the beam waists for a scalar and conical horn by calculating the ratio of their grains =... 

Our primary use of reflectors has been as elements in a Fabry-Perot resonator (cf. Section VI). If reflectors are used as focusing elements instead of lenses, it is common to use nonnormal incidence to avoid truncation losses. The choice of reflecting optics with nonnormal incidence does introduce aberrations in the reflected field, the most serious of which is coma (Murphy, 1987). 

We see that reducing the beam waist increases We note that is more weakly dependent on P. We will derive an expression for he field at the sample in a Fabry-Perot resonator in Section VIII after we have developed the appropriate lumped equivalent circuit for a transmission mode spectrometer. 

Due to the finite beam growth of a Gaussian beam, there will be a phase error that causes the surface reflectivities to be slightly different for the two surfaces. The response of a Fabry-Perot resonator with surfaces of different reflectivities is given in Section X, where we show that the minimum reflected power differs slightly from zero for surfaces with slightly different reflectivities. 

Although all laboratories that perform high-field ESR have experimented with Fabry-Perot resonators instead of fundamental mode microwave cavities, few laboratories have as yet explored quasioptical implementations of common microwave devices such as a magic T or circulator in an FIR-ESR spectrometer (see Earle and Freed, 1995 Earle et al. 1996b Smith, 1995). Part of the problem is the unfamiliar appearance of optical circuits to spectroscopists who are only familiar with... 

Fig. 12. Fabry-Perot resonator with one mirror of variable reflectivity r, and one mirror of variable reflectivity r2 - (a) Dashed line = 0.9 solid line r-j = 0.8 dot-dash line r, = 0.7 and r-2 = 0.8. (b) Planar Fabry-Perot interferometer that shows the effect of beam growth between the mirrors. The transmitted beam is a superposition of all the partial waves to the right of m,.

The unfiltered OLED shows a deep absorption peak due to the Fabry-Perot resonance of the naturally-occurring weak microcavity, and the filtered OLED shows oscillations in the reflectance due to the same effect. Lower reflectance filters could be designed with more layers in the DBR, at the expense of added complexity. 

G. Phase Properties of Radiation in Fabry-Perot Resonator... 

Our consideration so far have applied to photons in an ideal spherical cavity. Consider now the very important case of interaction between a single atom with electric dipole transition and cavity field in the case of Fabry-Perot resonator formed by two parallel ideal reflecting mirrors. In this case, the cavity field can consist only of the photons propagating along the axis of resonator (z axis) because all other photons should leave the space limited by the mirrors. This means that the cavity photons have well-defined direction and therefore are in a state with given linear momentum (21)-(22). Hence, the radiation emitted by the electric dipole transition consists of the two modes with m = 1, while the radiation of the third mode m 0 is forbidden. In this case, the photons with given helicity can be represented in terms of linearly polarized photons as follows [27] ... 

Since the atom-field interaction in the Fabry-Perot resonator is allowed for the two electric dipole transitions... 

This result is obtained by analogy with (79)-(81). Thus, unlike the case of spherical cavity, the spectrum of the SU(2) phase of photons in the Fabry-Perot resonator is trivial. 

The quantum fluctuations of the radiation phase manifest qualitative difference from those calculated within the Pegg-Barnett approach. In particular, the phase bunching effect can be observed for a multipole radiation in a spherical cavity in the quantum domain of low intensity. This effect does not occur in a linear cavity (Fabry-Perot resonator). 

---