20 June 2001 Optimum source concepts for optical intersatellite links with RZ coding
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Proceedings Volume 4272, Free-Space Laser Communication Technologies XIII; (2001) https://doi.org/10.1117/12.430776
Event: Photonics West 2001 - LASE, 2001, San Jose, CA, United States
We discuss several potential methods of generating optical RZ data signals, distinguishing between direct RZ modulation and modulation of a primary pulse train which is either generated by using a modelocked laser, by sinusoidally driving of an external modulator, or by gainswitching of a laser diode. We analyze the properties of each method with regard to the most critical aspects for space-borne laser communication systems such as repetition rate, duty cycle, extinction ratio, frequency chirp, timing jitter, robustness, complexity, commercial availability, and lifetime. Most modelocked lasers are highly sensitive to ambient perturbations, necessitating accurate temperature control and mechanical stabilization. Also, they typically provide pulses with less than 10% duty cycle, which can result in a decreased sensitivity of optically preamplified receivers. Directly modulated semiconductor lasers are compact and robust but suffer from large frequency chirp, which deteriorates the receiver sensitivity. One reliable RZ source is a conventional DFB semiconductor laser with two intensity modulators, one for pulse generation and one for data modulation. Both Mach-Zehnder modulators co-packaged with a laser diode or monolithically integrated electroabsorption modulators should be considered. These modulators can provide almost transform-limited pulses at high repetition rates and with duty cycles of about 30%. Robustness and lifetime are highly promising.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Martin M. Strasser, Martin M. Strasser, Peter J. Winzer, Peter J. Winzer, Walter R. Leeb, Walter R. Leeb, "Optimum source concepts for optical intersatellite links with RZ coding", Proc. SPIE 4272, Free-Space Laser Communication Technologies XIII, (20 June 2001); doi: 10.1117/12.430776; https://doi.org/10.1117/12.430776

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