Surface-normal electro-absorption modulator reaches 8:1 contrast ratio

Researchers at AT&T Bell Laboratories (Holmdel, NJ) have fabricated a surface-normal electro-absorption multiple-quantum-well (MQW) modulator that attained an extinction ratio exceeding 8:1 at 1550 nm, believed to be the highest contrast ratio achieved for this type of modulator. Designed for fiber-to-the-home applications, the device is advantageous because it eliminates the need for a laser diode at the subscriber terminal.

Surface-normal electro-absorption modulator reaches 8:1 contrast ratio

Researchers at AT&T Bell Laboratories (Holmdel, NJ) have fabricated a surface-normal electro-absorption multiple-quantum-well (MQW) modulator that attained an extinction ratio exceeding 8:1 at 1550 nm, believed to be the highest contrast ratio achieved for this type of modulator. Designed for fiber-to-the-home applications, the device is advantageous because it eliminates the need for a laser diode at the subscriber terminal.

The device had a 200-period InGaAs/In¥MQW structure in the intrinsic region of the PIN structure. The high contrast ratio was obtained by working in reflection and growing a large number of quantum wells to maximize the change in optical absorption. The calculated insertion loss was 7.7 dB, with bias voltages ranging u¥to 50 V. The researchers are working on designs to reduce the voltage requirements.

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