High Power MQW Electroabsorption Modulator with a Waveguide Taper

Abstract

Peripheral coupled waveguide (PCW) electroabsorption modulator (EAM) with different dimensions is studied. By incorporating a waveguide taper in the PCW to reduce the absorption at the input facet of the EAM, we show that the saturation effect due to high current density can be reduced.

Frequency dependence in RF gain resonance by negative photocurrent resistance of electroabsorption modulator

“…With the introduction of a peripheral coupled waveguide, where the active multiple-quantum-well layer is inserted near the edge of the waveguide, an EAM that can handle very high optical power (up to ~25 dBm) has been realized [6,7]. At this high optical power level, however, the junction resistance of the EAM becomes very small due to the generation of photocurrent.…”

Gain–bandwidth relation of electroabsorption-modulated analogue fibre link: effect of photocurrent resistance

“…As the optical power driving the analogue fibre link has been increased to achieve higher radio-frequency (RF) gain, the operation of the EAM under high optical power has been studied and designs that enable the high-optical-power operation have been suggested. By combining the diluted waveguide that absorbs much reduced optical power per unit length and the modified quantum-well design [6][7][8], an EAM has been demonstrated to handle a very high optical power up to 25 dBm ( 320 mW) [9].Under this very high optical power, however, the analogue fibre link that utilises an EAM has been shown to have saturation in RF gain owing to the photocurrent resistance inherent in the EAM device [9][10][11][12]. The photocurrent resistance R ph is given by (dI ph /dV ) 21 , where I ph is the photocurrent generated in the EAM and V is the reverse bias voltage supplied to the device.…”

“…As the optical power driving the analogue fibre link has been increased to achieve higher radio-frequency (RF) gain, the operation of the EAM under high optical power has been studied and designs that enable the high-optical-power operation have been suggested. By combining the diluted waveguide that absorbs much reduced optical power per unit length and the modified quantum-well design [6][7][8], an EAM has been demonstrated to handle a very high optical power up to 25 dBm ( 320 mW) [9].…”

“…Under this very high optical power, however, the analogue fibre link that utilises an EAM has been shown to have saturation in RF gain owing to the photocurrent resistance inherent in the EAM device [9][10][11][12]. The photocurrent resistance R ph is given by (dI ph /dV ) 21 , where I ph is the photocurrent generated in the EAM and V is the reverse bias voltage supplied to the device.…”

“…As the photocurrent resistance reduces with optical power, the signal voltage drop at the active junction decreases and the saturation in RF gain occurs. In [9], for example, it is shown experimentally that the compression factor in the RF gain reaches up to 23 dB at an optical power of 25 dBm.…”