Google Patents Single mode fiber with cut-off wavelength displacementĭownload PDF Info Publication number CN106772788B CN106772788B CN201710100067.6A CN201710100067A CN106772788B CN 106772788 B CN106772788 B CN 106772788B CN 201710100067 A CN201710100067 A CN 201710100067A CN 106772788 B CN106772788 B CN 106772788B Authority CN China Prior art keywords cladding optical fiber wavelength refractive index range Prior art date Legal status (The legal status is an assumption and is not a legal conclusion. Google Patents CN106772788B - Single mode fiber with cut-off wavelength displacement Another way to say it is that in the low frequency limits, things just blend in with the classical treatment of things and a quantum treatment is not necessary.CN106772788B - Single mode fiber with cut-off wavelength displacement Low energy photons abound, but when you get below radio frequencies, the photon energies are so tiny compared to room temperature thermal energy that you really never see them as distinct quantized entities - they are swamped in the background. On the upper side, there are practical limits because you have limited mechanisms for creating really high energy photons. It occurs in quantized chunks of 2.76 eV, and you can't have half a photon of blue light - it always occurs in precisely the same sized energy chunks.īut the frequency available is continuous and has no upper or lower bound, so there is no finite lower limit or upper limit on the possible energy of a photon. For example, a photon of blue light of wavelength 450 nm will always have 2.76 eV of energy. The quantization implies that a photon of blue light of given frequency or wavelength will always have the same size quantum of energy. The quantum of energy for a photon is not Planck's constant h itself, but the product of h and the frequency.
CalculationĪre there limits on the frequency of a photon?Īccording to the Planck hypothesis, all electromagnetic radiation is quantized and occurs in finite "bundles" of energy which we call photons. The quantum idea was soon seized to explain the photoelectric effect, became part of the Bohr theory of discrete atomic spectra, and quicklybecame part of the foundation of modern quantum theory. This would imply that higher modes would be less populated and avoid the ultraviolet catastrophe of the Rayleigh-Jeans Law. The Planck Hypothesis In order to explain the frequency distribution of radiation from a hot cavity ( blackbody radiation) Planck proposed the ad hoc assumption that the radiant energy could exist only in discrete quanta which were proportionalto the frequency. Further analysis Table of photoelectric effect work functionsĮarly Photoelectric Effect Data Planck hypothesis
Using this wavelength in the Planck relationship gives a photon energy of 1.82 eV. The threshold for this element corresponds to a wavelength of 683 nm.
The minimum energy required to eject an electron from the surface is called the photoelectric work function. Finding the opposing voltage it took to stop all the electrons gave a measure of the maximum kinetic energy of the electrons in electron volts. Photoelectric Effect Early Photoelectric Effect DataĮlectrons ejected from a sodium metal surface were measured as an electric current.
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