Single mode operation, of laser

This is the reason why virtually all single-mode lasers use internal mode selection. We now discuss some experimental possibilities that allow stable single-mode operation of lasers with internal mode selection. As pointed out in the previous section, all methods for achieving single-mode operation are based on mode sup-... 

Fig. 3.5 Experimental arrangement for intracavity Raman spectroscopy with an argon laser CM, multiple reflection four-mirror system for efficient collection of scattered light LM, laser-resonator mirror DP, Dove prism, which turns the image of the horizontal interaction plane by 90° in order to match it to the vertical entrance slit S of the spectrograph FPE, Fabry-Perot etalon to enforce single-mode operation of the argon laser LP, Littrow prism for line selection [315]...

In order to improve on the spectral purity, i.e. reliable single-mode operation of diode lasers, their resonator design needs to be altered. Both of the common solutions work on grating-induced wavelength-selective feedback. 

For reliable single-mode operation of the Littman laser longitudinal pumping is better than transverse pumping, because the dye cell is shorter and inhomogenities of the refractive index caused by the pump process are less severe [5.183J. 

For high-resolution spectroscopy the bandwidth of the dye laser should be as small as possible. With two etalons having different free spectral ranges, single-mode operation of the Hansch-type laser (Fig. 5.83) can be achieved. For continuous tuning both etalons and the optical length of the laser resonator must be tuned synchronously. This can be realized with computer control (Sect. 5.4.5)... 

M. Hercher Tunable single mode operation of gas lasers using intra-cavity tilted etalons. Appl. Opt. 8, 1103 (1969)... 

M. Pinard, M. Leduc, G. Trenec, C.G. Aminoff, F Laloc Efficient single mode operation of a standing wave dye laser. Appl. Phys. 19, 399 (1978)... 

M.G. Littman Single-mode operation of grazing-incidence pulsed dye laser. Opt. Lett. 3, 138 (1978)... 

H.W. Schroder, H. Dux, H. WeUing Single-mode operation of CW dye lasers. Appl. Phys. 

The two prisms narrow the spectral width of the gain profile above threshold to about 100 GHz. If the free spectral range of the thin etalon is 100 GHz (=AA Inm at A = 600 nm) and that of the thin etalon is 10 GHz, single-mode operation of the CW dye laser can be achieved. This demands tj = 0.1 cm and t2 = 1 cm. 

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