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A compact 1 × 8 waveguide splitter using a guided‐wave microlens array is presented and analyzed to show low insertion loss and output imbalance of 0.28 and 0.15 dB, respectively. The analysis results show that the proposed equal‐power splitter with insensitive wavelength responses and acceptable fabrication tolerances is applicable for compact and wide‐bandwidth integrated optical devices. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 29–33, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20365

We have studied experimentally the temporal and spectral characteristics of an actively mode-locked laserdiode array in an external cavity as it evolves to the steady state. It is found that the buildup time to steadystate picosecond pulses takes less than 45 round trips. The number of clusters of the longitudinal-mode spectrum reduces during the evolution and finally approaches a steady-state spectral distribution with the pulse energy mainly distributed among a few clusters near the line center.

Dynamic pulse evolution characteristics of an actively mode-locked laser diode array in the external cavity have been investigated. Numerical calculations based on modified traveling-wave rate equations reproduce experimentally observed pulse and spectral width evolution and show that the buildup time is about 45 round-trips. We have also performed a theoretical analysis to understand which of the laser operating parameters would affect the buildup dynamics. It is shown that either higher dc bias current or larger radiative recombination coefficient (which is inversely proportional to the excited-state lifetime) will render the laser exhibiting shorter steady-state pulse width and faster evolution to the steady state. Other parameters affecting the buildup, but to a lesser extent, include the radio-frequency (RF) modulation current, spontaneous emission coefficient, and gain coefficient. The power reflectivities of the output mirror and the antireflection coated diode facet, on the other hand, have little effect on the pulse width and buildup time for single pulse generation.