Bandgap tuning of lasers, modulators, and passive waveguides in GaInAsP using photoabsorption-induced disordering

The bandgap of GaInAsP multi-quantum well (MQW) material can be accurately tuned by photo-absorption induced disordering (PAID) to allow lasers, modulators and passive waveguides to be fabricated from a standard MQW laser structure. The bandgap tuned lasers are assessed in terms of threshold current density, internal quantum efficiency and internal losses and exhibit blue shifts in the lasing spectra of up to 160 nm. The ON/OFF ratios of the modulators were tested over a range of wavelengths with modulation depths of 20 dB obtained from material which has been bandgap shifted by 120 nm, while samples shifted by 80 nm gave modulation depths as high as 27 dB. We have also measured single mode waveguide losses over a range of wavelengths and these are 5 dB/cm at 1550 nm. These high quality devices showing good electrical and optical properties after processing demonstrate that PAID is a promising technique for the integration of devices to produce photonic integrated circuits.