Nonlinear Optics Produces Why Do Nonlinear-optical Effects Occur? Many Exotic Effects Recall that in normal linea otics, a light wave Sending infrared light into a acts on a molecule, which vibrates rystal yielded this display of its own light wave that interferes with the original green light light wave Emitted wave switch avelength light ever made by process in terms of the molecular energy levels, using Molecular energy levels arrows for the photon energies: Why Do Nonlinearoptical Effects Occur? The invention of lasers led to (Continued) Now, suppose the irradiance is h nat many the lower level fo xcitation. This ibrations at all frequenc ding to all energy differences between popul decade ported about three des ago and the aterials models and synthesis. TI 亚!xw Tod lint New color!!t molecular energy levels Nonlinear Optics Effect and NLO Materials Pulsed laser oscillator where the intensity of the optical wave changes YAG laser consists of a rod of aterials can be used to double the the material which can be pumped by a flash lamp of laser radiation Useful as short at a rate of about 15 Hz. The output consists of an envelope of pulses which can be tuned for be difficult to make short optimization by adjusting the mirrors, adjusting length radiation better for information he prisms to change optical path b Nonlinear optic (NLO) crystals are used for the crystal in the acoustic adjusting the frequency of ther and8 (SHG), tripling(3HG), freque scillator)and mIxing, we from the original laser output10 Nonlinear Optics Produces Many Exotic Effects Sending infrared light into a crystal yielded this display of green light: Nonlinear optics allows us to change the color of a light beam, to change its shape in space and time, to switch telecommunications systems, and to create the shortest wavelength light ever made by Man. Why Do Nonlinear-optical Effects Occur? Recall that, in normal linear optics, a light wave acts on a molecule, which vibrates and then emits its own light wave that interferes with the original light wave. We can also imagine this process in terms of the molecular energy levels, using arrows for the photon energies: Why Do Nonlinear-optical Effects Occur? (Continued) Now, suppose the irradiance is high enough that many molecules are excited to the higher-energy state. This state can then act as the lower level for additional excitation. This yields vibrations at all frequencies corresponding to all energy differences between populated states. The invention of lasers led to the discovery of interesting nonlinear optical phenomena in inorganic as well as organic materials. Nonlinear optical effects in organic materials were reported about three decades ago and the importance of novel materials was realized through theory models and synthesis. The extraordinary growth and development of NLO materials during the past decade has made photonic technologies an indispensable part of our daily life as we enter the 21st century, the "INFORMATION AGE". Nonlinear Optics Effect and NLO Materials Nonlinear optics describes many interactions where the intensity of the optical wave changes the optical properties of a material. NLO materials can be used to double the frequency of laser radiation ¾¾ Useful as short wavelength. Lasers can be difficult to make short wavelength radiation better for information storage and transmission. Nonlinear optic (NLO) crystals are used for harmonic generation, including frequency doubling (SHG), tripling (3HG), frequency mixing; OPO(Optical Parametric Oscillator) and OPA(Optical Parametric Amplifier). Combining harmonic generation and frequency mixing, we can generate the 4th, 5th, or even 15th harmonics from the original laser output. Pulsed Laser Oscillator The Neodymium-YAG laser consists of a rod of the material which can be pumped by a flash lamp at a rate of about 15 Hz. The output consists of an envelope of pulses which can be tuned for optimization by adjusting the mirrors, adjusting the prisms to change optical pathlength, adjusting the crystal in the acoustic-optic modulator, and adjusting the frequency of the modulator