Vacuum coating vendors would introduce coating control mode wavelength

Vacuum coating vendors would introduce coating control mode wavelength

Vacuum coating machine, vacuum coating vendors would introduce our materials for its membrane layer of materials, figure 1. The experimental results obtained for SiN film plating. Curve 1 is the reflection spectrum of epitaxial wafer before coating, curve 2 and 3, respectively corresponding to the film thickness of 95 nm and 135 nm, film thickness with elliptic partial instrument to measure. From the curve 1, film e - lh peak at 840 nm, e - hh peak at 848 nm, the location of the pattern wavelength at 832 nm. In type Chang Tong modulator, mode wavelength position should be in e ￣ hh peak of long wavelength direction; And often shut device, pattern wavelength location should be near the e - hh peak, and the top must be decreased membrane plating, otherwise the device will work in the saturated zone, reduce the modulation features of the device. Because the pattern wavelength position is not appropriate, to adopt the method of plating SiNO minus the membrane to move mode wavelength.
Vacuum coating machine, vacuum coating vendors would introduce 2 film thickness of 95 nm by curve of reflection spectrum, the wavelength shifted, but as a result of surface reflectivity, ASFP cavity resonance absorption and exciton absorption compared to compare weak, so can not see clearly on the curve mode wavelength position. Measured with elliptic partial instrument, the film refractive index of 1.8 or so, move about 10 nm wavelength by a theoretical calculation of the mode, at about 842 nm. After coating, e - hh peak of significantly lower reflectivity, although the model at this time Wavelength in e - hh peak position, but because the pattern wavelength from closer to make e - hh exciton peak near the reflectivity of reduce a lot.
Vacuum coating machine, vacuum coating vendors would introduce three film thickness of 135 nm by curve reflection spectrum shows that compared with the mode wavelength before coating, coating mode wavelength decreases after, from the original 832 nm to 832 nm. Film refractive index is 1.8, from the above theoretical analysis shows that when the refractive index of 1.8, film thickness increased to 135 nm, the model about 10 nm wavelength will drop, curve 3 belongs to this kind of situation.