Output coupling

A dc restoration circuit is needed following the output coupling capacitor to make the drive voltage referenced to the power switch s common. The supply voltage of the driver should be well bypassed so that its voltage does not droop during the drive pulse. 

Fig. 5.2 Hemispherical prism coupling scheme. The microsphere is in a V groove channel for the solvent and analyte. Left, polar view showing input and output coupling. Right, equatorial view illustrating how precessed light is collected at the drop port. Reprinted from Ref. 3 with permission 2008 Optical Society of America...

C.F. Madigan, M.H. Lu, and J.C. Sturm, Improvement of output coupling efficiency of organic light-emitting diodes by backside substrate modification, Appl. Phys. Lett., 76 1650-1652, 2000. 

The information about the losses in the material under investigation lies within the unloaded quality factor. In case of measurements at low levels of rf power weak coupling (Qexti, Qext2 Ql) resulting in Qo Ql is of common use. For measurements of the power dependence matched input coupling (Qexti Qo) and weak output coupling conditions should be adjusted (e.g. by a mechanical adjustment of coupling antennae position inside a cavity resonator). 

The apparatus used to perform vibrational relaxation experiments in supercritical fluids consists of a picosecond mid-infrared laser system and a variable-temperature, high-pressure optical cell (68,73). Because the vibrational absorption lines under study are quite narrow (<10 cm-1), a source of IR pulses is required that produces narrow bandwidths. To this end, an output-coupled, acousto-optically Q-switched and mode-locked Nd YAG laser is used to synchronously pump a Rhodamine 610 dye laser. The Nd YAG laser is also cavity-dumped, and the resulting 1.06 pm pulse is doubled to give an 600 u.l pulse at 532 nm with a pulse duration of "-75 ps. The output pulse from the amplified dye laser ("-35 uJ at 595 nm, 40 ps FWHM) and the cavity-dumped, frequency-doubled pulse at 532 nm... 

Furthermore, for the face detected emission (as usually is the case), the light output coupling factor (287) reduces the measured Oel to OgE, so that we deal with the external quantum EL efficiency... 

As illustrated in Fig. 9 and described in Sect. 3.1.2, prior to sputtering deposition of the layers, two surface relief gratings (period of A = 400 nm) were fabricated on the glass slide for input and output coupling of the optical beam. A calculation based on the theory developed in Sect. 2.2 gave an electric field profile for the TE mode as shown in Fig. 10. 

Fig. 21. Schematic representation of a subsonic C02 laser with purely chemical excitation (after Cool82)). A He and Fg injectors, H CO2 and NO inlet, C construction detail shown in B, L D2 mixing array, K part of the D2 inlet system which is shown in detail in J, D sodium chloride window, E totally reflecting cavity mirror with long focal length, M, F beam-folding (plane) mirrors, O partially reflecting cavity mirror for output coupling, N laser beam, G resonator housing flushed with nitrogen...

Single-mode operation was achieved by closing down the variable iris in front of the output coupling mirror. The mirror itself was mounted on a piezoelectric transducer, which is capable of converting an applied voltage into a proportional extension of the element (Lansing 80-214 Lock-In... 

Using Equation 68, four Q s will now be defined appropriate for a transmission Fabry-Perot cavity. The unloaded Q, Qq accounts for power dissipation in the cavity. Similarly, the input and output coupling Q s are labelled Qd and Qc2 The sum of all dissipative elements defines the loaded Q, Q ... 

For the transmission cavity considered here, some power will always be coupled out through the output coupling iris. If we call Pp the power reflected from the input to the cavity, then... 

Fig. 6.16 Cavity-dumped synchronously pumped dye laser system with synchronization electronics [Courtesy Spectra-Physics] (a) experimental setup (b) correct synchronization time of a mode-locked pulse with the time of maximum output coupling of the cavity dumping pulse...

When the gain exceeds the total optical losses a due to mirror output coupling, scattering losses, and resonator losses, then net amplification and lasing is achieved. The threshold popnlation inversion is defined as the inversion reqnired for the gain to eqnal the losses ... 

FIGURE 14 Littrow-oriented diffraction grating tuner for a tunable laser. The zeroth-order reflection is used for output coupling, while the first-order reflection is fed back into the laser. 

The analysis uses the optimum output coupling values / = to determined ejqterimentally with the tuning curves and the estimate of the single-frequency cavity chssipative losses a = 2.5% for the ring laser of Fig. 10. Differentiating Eq. (9) with respect to t to find the output minor transmission that maximizes the output power gives... 

FIGURE 25 Typical output coupling methods for confocal unstable resonators. 

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