Zero-loss quantum well waveguide Mach–Zehnder modulator at 1.55 μm

We report the first interferometric waveguide intensity modulator with optical gain. A monolithically integrated compressively strained InGaAs quantum well amplifier provides a net 4.2 dB fiber-to-fiber gain at 120 mA forward bias. Reversed-biased InGaAsP quantum wells provide enhanced electrorefraction for the modulator in which we demonstrate a 3 dB electrical modulation bandwidth of 2.25 GHz. The voltage-length product for 180° phase shift is a record Vπ × L = 1.9 V mm. The total device length is under 2 mm.