Multiple-wavelength GaInAs-GaAs vertical cavity surface emitting laser array with extended wavelength span

The wavelength engineering of vertical cavity surface emitting lasers (VCSEL) on a nonplanar substrate enables us to realize a multiwavelength VCSEL array. We are able to control the wavelength of both a cavity resonance and the gain peak of an active region, depending on patterned shapes. A main limiting factor in expanding the wavelength span in arrays is the offset between the gain peak and the resonant wavelength. In order to overcome this offset, we optimized a gain-cavity detuning to extend the wavelength span. A wavelength span of over 100 nm was obtained from a fabricated 12-channel array. The output power is over 1 mW, and threshold current is 0.65 ± 0.2 mA. We carried out the compensation of the threshold current-density variation by the precise control of oxide apertures in each element. In addition, we proposed a growth-pressure control in epitaxial growth on a patterned substrate for further extension of the lasing wavelength span. We demonstrated a 0.96-1.16-μm multiple-wavelength VCSEL array with highly strained GaInAs-GaAs QWs exhibiting a record wavelength span of 192 nm. These technologies would enable low-cost wideband wavelength division multiplexing data links.