Abstract: A method in which a (display) device having a part (41) comprising a first wall (43) and a second wall (44) is manufactured, which part (41) is warmed up during the temperature treatment by unilateral irradiation with heat by means of heat radiators (35). The method is characterized in that the temperature treatment further comprises measures which cause a fluid (53) to be fed past the outer surface of the first wall (43) to remove heat from said outer surface and/or measures which cause a fluid to be fed past the inner surface of the second wall (44) to supply heat to said second surface. In an embodiment, the inner surface of the second wall (44) is provided with a heat-absorbing coating (48). Preferably, the heat radiators (35) emit electromagnetic radiation having a wavelength below 3 .mu.m.

Abstract: Device (1) for raising the frequency of electromagnetic radiation. The device (1) comprises a diode laser (3) for generating the radiation, and a non-linear optical medium (11) in which a first optical waveguide (9) is arranged for guiding a fundamental wave of the diode laser radiation while forming a higher harmonic wave. Moreover, the device (1) comprises a wavelength stabilizer (5) for stabilizing the wavelength of the fundamental wave. The wavelength stabilizer (5) is constituted by a second optical waveguide (13) with a refractive index grating extending in its longitudinal direction and whose selection wavelength is electrically controllable by means of an electrode structure (15; 29).

Abstract: A device for doubling the frequency of a light wave and having a satisfactory waveguide action is obtained in a simple manner by providing, in a nonlinear optical material 11, periodic domains 12 having a reduced second-order susceptibility and an increased refractive index relative to the nonlinear optical material by means of proton exchange or proton implantation. By means of a heat treatment, the refractive index of the material in the periodic domains is reduced to a value which is less than 0.10 higher than that of the nonlinear optical material, thus obtaining a low degree of light scattering.