A quantum-well waveguide photodetector for high-precision wavelength monitoring about 1.55 mu m

A two-segment InGaAsP rib waveguide photodetector is shown to function as a high resolution wavelength monitor in the 1.55-mu m spectral region. For t wo in-line detector elements, the ratio of photocurrents produced is a sens itive function of the input wavelength near the material's absorption edge. This ratio varies rapidly with wavelength over a range from 1.53 to 1.565 mu m and is independent of the optical input power, By utilizing the quantu m confined Stark effect, the operating range of the device can be extended to over 50 nm, An average wavelength sensitivity of 3 pm is demonstrated.