Monolithic tunable semiconductor lasers using photon recycling

A novel monolithic tunable semiconductor laser is demonstrated. It consists of a laser diode integrated on top of a photodiode. The tunable range of this device depends on the optical coupling between the laser diode and the photodiode. Through photon recycling, the threshold pump power and the threshold current of the device were reduced by 21.1% and 5.1%, respectively. According to our model, the 5.1% reduction of the threshold current corresponded to a calculated 3.3 nm wavelength shift.