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Abstract-A novel design strategy for the epitaxial structure of monolithic mode-locked semiconductor lasers is presented. Using an all-active design, we fabricate 40-GHz lasers generating 2.8-ps almost chirp-free pulses with record low high-frequency jitter and more than 7-mW fiber coupled output power.

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Dynamic and static tests were performed on 523 lumber specimens of Norway spruce (Picea abies) of three different cross sectional sizes: 38 x 89 mm 2, 38 x 140 mm 2, and 38 x 184 mm 2. Specific material characteristics for the lumber are presented. The tests also enabled comparison between results from two testing methodologies. The mean value for the modulus of elasticity established from the dynamic tests was found to be approximately 10% higher than the corresponding value established from static tests. The statistical correlation between statically and dynamically established moduli is very strong. The dynamic E modulus was found to be as good a strength predictor as the static E modulus. Cross sectional size and the existence of the pith in the sawn lumber were found to significantly influence the material properties. In general terms, it was found that deeper beams correspond to lower values for the E modulus and for the bending strength. The reason for this tendency is believed to be a combination of a volumetric effect (in the case of strength) and a phenomenon related to the log selection and sawing process in the mills. Lumber that comprises the pith has been found to have generally lower values of the E modulus and bending strength while the shear modulus is higher, compared to lumber without pith sawn further out in the log. Mechonische Eigenschcrften von FichtenschnittholzAn 525 Schnittholzproben (Picea abies) wurden dynamische und statische Priifungen vorgenommen. Die Proben hatten drei verschiedene Querschnitte: 38 x 89 mm 2, 38 x 140 mm 2 und 38 x 184 mm 2. Anhand der vorgelegten Ergebnisse wurden auch zwei Priifmethoden verglithen. Die Mittelwerte der dynamischen MOE-Prfifung lagen etwa 10% h6her als die statisch ermittelten Werte. Die Korrelation beider MOE-Werte ist sehr streng. Beide Werte k6nnen zur Vorhersage der Festigkeit verwendetThe dynamic tests and subsequent evaluation and comparison between dynamic and static test data were made within a project concerning the determination of viscoelastic properties of anisotropic materials by modal testing, which is financially supported by the Swedish Research Council for Engineering Sciences (TFR) in grant No. 261-94-344; this is gratefully acknowledged. werden. Der Querschnitt und die Anwesenheit von Markanteilen beeinflussen das Ergebnis wesentlich. Je tiefer die Balken waren d.h. je n~iher sie der Markr6hre lagen, desto geringer waren E-Modul und Biegefestigkeit. Die Grfinde dafiir werden tells einem Volumeneffekt zugeschrieben (ira Falle der Festigkeit), tells auf das Auswahlverfahren der St~imme im S~igebetrieb zurfickgeffihrt. Schnittholz mit Markanteil hatte allgemein, einen geringeren E-Modul und niedrigere Biegefestigkeit als Proben aus iiufleren Stammbereichen; die Scherfestigkeit lag dagegen h6her.

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