STH51005GE9302 データシートの表示（PDF） - Infineon Technologies
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STH51005GE9302 Datasheet PDF : 10 Pages
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STH51004x
STH51005x
Description
Description
Differences between a Fabry-Perot and a DFB Laserdiode
A conventional laser consists of an amplifying medium and two end mirrors. The cavity
is longer than one wavelength, and a standing wave is created. The number n of half
wavelengths λ is n = 2 × L-λ- . If L >> λ then we speak of a Fabry-Perot Laser because the
laserdiode emits multi-longitudinal modes. Typically the laserdiode is 250 µm long. For
λ = 1310 nm/1550 nm n is about 350. Therefore for many neighboring wavelengths the
“standing wavelength” condition specified above is fulfilled. For a DFB-Laser a special
grating acts as a distributed filter allowing only one of the cavity’s longitudinal modes to
propagate. This can be described with a reduced oscillator length L˜ which is in the range
of λ. For such a reduced oscillator length the standing wavelength condition will be
fulfilled for n ≈ 2 what means for only one wavelength.
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Wavelength λ
Figure 2 Fabry-Perot Laserdiode
Data Sheet
3
2001-06-01
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