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Critique of Present and Future Problems in the Far Infrared

The coherent radiation history of the far IR began around 1960-62 with the extension of the Compagnie Genérale de Telégraphie sans Fils 0 type Carcinotrons down to 500 μm wavelength and the extension of the He-Ne laser by Bell Telephone Laboratories first to 28 and later to 133 μm wavelength [1,2]. Less than a year later, the British Services Electronics Research Laboratory announced the first far IR molecular lasers (H2O and HCN) operating at 78 and 337 μm wavelength [3].