Proposal of optically pumped tunable surface emitting laser

A tunable laser is a key device for providing flexibility and functionality in future Wavelength Division Multiplexing networks. We propose a novel optically pumped tunable surface emitting laser. The lasing wavelength of the device can be varied by changing the photo-pumped position of a vertical cavity with a spatial gradient in the cavity length. A possibility of mode-hop-free wide wavelength tuning is presented over current existing tunable lasers. We fabricated a GaInAsP/InP short cavity and measured the resonant spontaneous emission of an optically pumped cavity with spatial gradient. The change of the resonance peak is as large as 40 nm. The obtained result shows the possibility of large continuous wavelength tuning.