Browsing by Author "Lim, Cheng Guan"

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A Passive Broadband Impedance Equalizer for Improving the Input Return Loss of Electro-Absorption Modulators
(2009-03-01)
Lim, Cheng Guan
;
光電工程學系
;
Department of Photonics
Based on the context of an electro-absorption modulator integrated laser and the industry's standard 7-pin package having a RF connector, a complete module design that incorporates a simple yet effective broadband impedance equalizer to improve the input return loss of electro-absorption modulators (EAM) is proposed. The passive broadband impedance equalizer effectively reduces the input return loss of the EAM from between -9.84 and -5.26 dB to between -11.5 and -9.35 dB over a frequency range from 4.4 to 12.2 GHz without having to add a resistor in series with the EAM or reducing the EAM absorption-layer capacitance from the value that was optimized for optimal optical performance.
Electro-absorption modulator integrated lasers with enhanced signal injection efficiency
(2008-03-01)
Lim, Cheng Guan
;
光電工程學系
;
Department of Photonics
By incorporating a lumped-element impedance-matching network on the laser diode carrier/submount, the signal injection efficiency of electro-absorption modulator integrated lasers is significantly improved through the reduction of input return loss. Over a frequency range spanning from 5.8 to 10 GHz, an improvement of approximately 12% to 37% in signal injection efficiency is observed. To avoid increasing the component-count, a unique implementation of the lumped element impedance matching network is proposed.
The effect of signal-feeder characteristic impedance on the signal injection efficiency of electroabsorption modulator integrated lasers
(2006-10-01)
Lim, Cheng Guan
;
光電工程學系
;
Department of Photonics
The signal injection efficiency of electroabsorption modulator integrated lasers (EMLs) is improved to suit 10-Gb/s applications. For a typical EML module design with a conventionally designed 50-Omega signal feeder to meet the input return loss requirement for 10-Gb/s applications, a reduction in device capacitance of the electroabsorption modulator (EAM) section by 65% from its typical value is necessary. By optimizing the characteristic impedance of the signal feeder, the required 65% reduction in device capacitance of the EAM section is reduced to 45%, which would naturally lead to enhanced extinction ratio and optical output power. With the addition of a series 5-Omega thin-film resistor along the signal feeder, the device capacitance reduction of the EAM section is further reduced to approximately 33% of the typical value.