Frequency chirping properties of electroabsorption modulators integrated with laser diodes
Saravanan, Brem Kumar
FacultiesFakultät für Ingenieurwissenschaften
LicenseStandard (Fassung vom 03.05.2003)
Monolithic integration of an electroabsorption modulator with a distributed feedback laser (electroabsorption modulated lasers abbreviated as EMLs) is studied for optical communications in 1310 nm and 1550 nm wavelength windows employing a shared InGaAlAs/InP based multiple quantum well active layer. One of the prime concerns in the design and deployment of optical transmitters for long-haul communications is the frequency chirping behavior of the transmitter. To optimize the distance-bandwidth product, time-resolved chirp (TRC) evaluation is of paramount importance. An air-cavity based Fabry-Perot resonator was designed and implemented for time-resolved chirp characterization up to 40 Gb/s. Excellent agreement between theoretical predictions using Kramers-Kronig transformations and experimental observations was obtained. Perspectives, considerations and limitations of the implemented method for high-speed characterization were studied in a detailed manner, especially with respect to photon life-time. Quantum confined Stark effect based EMLs are inherently temperature sensitive. Wide temperature operation of EMLs between 20 ° C and 70 ° C at 40 Gb/s was demonstrated by counteracting extinction degradation by actively controlling modulator bias. Kramers-Kronig transformations of EML absorption characteristics show that negative chirp-parameters can be achieved only for very low optical power levels. Integration of EMLs with semiconductor optical amplifier was demonstrated to enable negative chirp parameters and boost optical output power simultaneously.
Subject HeadingsChirp [GND]
Optical communications [LCSH]