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Technology Stocks : SDL, Inc. [Nasdaq: SDLI] -- Ignore unavailable to you. Want to Upgrade?

To: Jack Hartmann who wrote (1695)	6/12/2000 2:33:00 PM
From: pat mudge	Respond to of 3951

Did they say who they percieve as the major competition? Searching different websites, I find little on Raman on either JDSU or ETEK's. The following are from Lucent and Nortel: searchus.lucent.com{_ALL}%3Cand%3E+Raman&topic=_ALL&BU=DEFAULT&collection=LU&resulttemplate=default.hts&action=filtersearch&filter=filter.hts&resultmaxdocs=200&sortfield=score&sortorder=desc&displayformat=full&resultcount=10&Yourquery=Raman&P1=y nortelnetworks.com On the latter, it's not clear if the Raman amplifiers came from Nortel or elsewhere. This is a long way of saying I don't know who is the biggest competitor to SDL on Raman. Now, I was wrong earlier this morning when I posted the Raman press release in response to the JPMorgan report on modulators. It said "modulators" and I read "modules." Subsequently, I've done some digging and I believe two acquisitions give the best clues: From Veritech Microwave: veritechmicro.com They provide the drivers for advanced system modulators. Next, go to SDLI's homepage and click on "SDLio Modulators": From "background on modulators": Introduction to Modulators 2.5 Gb/s, 5 Gb/s and 10 Gb/s External Modulators Modulators are currently the most commonly used integrated optical components. They function by controlling the amount of light transmitted into a fibre optic link from a continuous wave (CW) laser. The light transmitted through the modulator can be smoothly varied from zero to the maximum intensity. Modulator Operating Principles A Mach-Zehnder modulator comprises two phase modulators and Y-junction splitters/combiners. A schematic of the modulator is shown below: The operating principle is as follows: a voltage V(t) is applied to the central RF electrode. The optical signal is initially split into two equal portions at the 3dB Y-junction. In accordance with the electro-optic effect the induced index change causes the phase of the optical signals to be advanced in one arm and retarded in the other. When the signals are re-combined in the Y-junction combiner, they are coupled into the single mode output guide if they are in phase, whilst if they are out of phase they are transformed into a higher order mode and lost into the substrate. For phase differences between these two extremes only a portion of the light is coupled into the output waveguide. This gives rise to the characteristic cosinusoidal transfer function shown opposite. The transfer function for all integrated optical Mach-Zehnder modulators is exactly a raised cosine, the intensity of the modulator output being given by: Modulator Transfer Function This transfer characteristic is a fundamental property of the modulator, providing repeatable device to device performance over signal frequency, signal format and environmental conditions. The major benefit of external modulation compared to direct modulation techniques is the absence of frequency chirp. This is achieved through the use of a narrow linewidth CW laser source and the inherent characteristics of the external modulator. Normally configured to offer negligible chirp, the design of the modulator can be tailored to offer fixed chirp as required. Direct modulation techniques currently employed introduce a level of chirp, which when coupled with dispersion effects within the fibre itself, limit the viable transmission distance between repeaters. Modulator Bias SDLio's modulators incorporate a separate bias electrode. This enables the user to adjust the static transmission point of the modulator to suit the drive system being employed. The static bias of the modulator can be set to any point on the transmission curve and is independent of the RF drive electrode. Normal design practice typically uses two bias points. Quadrature Bias In this case the modulator is biased to the 50% transmission point. The following attributes are achieved: Suitable for bipolar RF operation Most sensitive section of the transfer function. This gives the highest microwave link efficiency in analogue transmission systems. All SDLio modulators are provided with test data that shows the voltage required to achieve quadrature point. For systems where extreme suppression of the second order products is required this electrode is often driven from a closed loop feedback control that dynamically holds the quadrature point to a very high degree of precision. Null Bias This is typically used in systems that require: Unipolar drive electronics Very high extinction ratios Attributes of External Modulation Most systems that use external modulators take advantage of a number of attributes. These are as follows: Negligible chirp. Using symmetrical modulator design and high return loss interfaces it is possible to minimise output frequency chirp to negligible levels. This ensures that the lasers CW linewidth is preserved, so minimising the effects of dispersion and maximising the bandwidth/length product of the system. As this attribute is totally independent of the signal data rate or format, such links have great flexibility and are easy to upgrade in the future. Access to modulation depths of greater than 20 dB Very high modulated optical powers can be generated Simplified drive electronics Excellent stability of the transmitter to temperature and environmental fluctuations This combination of features offer system designers the ability to: transmit data further develop cost effective networks minimise expensive intermediate amplification and signal processing elements develop wideband data transmission solutions <<<<<< For anyone who has Jeff Hecht's book, there's a good description of modulators on pp 316-319. Pat