<p>External modulators will become key components in fiberoptical communica- tion systems operating at 40Gbit/s andhigher bitrates. Semiconductor electro- absorption (EA)modulators are promising candidates because of their high-speed potential, and their process compatibility with thecorresponding semi- conductor laser light sources. Thetraveling-wave (TW) electrode concept for electro-opticmodulators has been used for a long time in order to resolvethe con°ict between high modulation depth and highmodulation bandwidth. Re- cently, it has been adopted for EAmodulators as well.</p><p>This thesis presents the work carried out on design,fabrication and analysis of traveling-wave EA modulators(TWEAM) based on InP-InGaAsP. The lengths of TWEAM arecomparable to the lengths of their lumped counterparts. Theexperimental data of this work were analyzed in order show thatthe traveling- wave concept results in better performance evenfor short EA modulators. One key issue is the impedancematching. The low intrinsic characteristic modulator impedancehas to be matched with a corresponding load. In this case, theTW con figuration leads to a much higher bandwidth than for alumped EA modulator with the same length and the same connectedload.</p><p>An InP process was developed allowing the fabrication ofTWEAM with integrated termination resistors. Experimentalmicrowave properties were ob- tained for different TWEAMgeometries. It is reported on long TWEAM that showstate-of-the-art bandwidth. A 450μm long TWEAM reached43GHz, and 67GHz (beyond characterization limit) were indicatedfor a 250μm device. The experimental results onmicrowave properties were compared to full-wave, and circuitmodel simulations. The analysis reveals an impedance bandwidthtrade- off for the cross sectional electrode configuration.</p><p>Results of a new high-impedance design in form of asegmented TWEAM are presented. The devices were processedwithin the frame of this work and record bandwidth performanceis reported. At 50Ω impedance a bandwidth in the90GHz region was indicated.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:kth-3566 |
| Date | January 2003 |
| Creators | Irmscher, Stefan |
| Publisher | KTH, Microelectronics and Information Technology, IMIT, Kista : Mikroelektronik och informationsteknik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Trita-MVT, 0348-4467 ; 2003:5 |
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