The laser emission of a cw diode laser coupled to an external cavity is self-pulsing at a frequency of 3–30 MHz, that is, two orders of magnitude lower than the resonance frequencies of the external cavity (typically 0.5 m long). The low-frequency self-pulsation is also present with a wavelength-selective external cavity using a grating as a reflector that narrows the laser emission to a single longitudinal mode. This paper describes some of the characteristics of the self-pulsation such as the pulse shape, the frequency dependence, the shift of the wavelength of the lasing mode during a pulse, and their dependence on the wavelength selection by the grating.
The light output and the electron density within the active layer of a semiconductor laser have been calculated from the steady state solution of a rate equation approach. The assumed rate equation model takes into account the spontaneous emission into the lasing modes. Simple analytical approximation formulae have been found under the assumption of a power-law dependence between optical gain g and electron density n (g oc nl). The approximations are compared with numerical results from the rate equations. With the exception of a small region near the lasing threshold good agreement has been found.The theoretical results are compared with experimentally measured light outputs from single and double heterostructure lasers. From the comparison below threshold the power law exponent / may be evaluated. The comparison at threshold suggests that the spontaneous emission term decreases at threshold. This decrease is in agreement with experimentally measured changes of the emission bandwidth at threshold.
Two diode lasers have been coupled by means of conventional optics. The coupling coefficient has been altered by inserting additional filters into the light path between the two diodes. The power output and the spectral behaviour of both diodes have been investigated as a function of the coupling coefficient. The power output measurements are compared with theoretical calculations based on a rate equation approach. The spectral measurement at the different coupling steps reveals t h a t both diodes emit the same spectra. The spectral width of the emission increases with an increasing coupling coefficient. Zwei Laserdioden wurden mittels konventioneller Optik gekoppelt. Durch dnderung der Transmission zwischen beiden Dioden wurde der Kopplungskoeffizient verandert. Gemessen wurde die AusgangsintensitLt und das spektrale Verhalten beider Dioden als Funktion des Kopplungsgrades. Die Intensitiitsmessungen werden mit theoretischen Ergebnissen, die &us einem System von Bilanzgleichungen hervorgehcn, verglichen. Die spektralen Messungen bei verschiedenen Kopplungskoeffizienten zeigen, daLi die Emission beider Dioden jeweils identisch ist. Die Bandbreite der spektralen Emission nimmt mit zunehmendem Kopplungskoeffizienten zu.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.