Researchers at the CAS Institute of Semiconductors (ISCAS) have made significant progress in their work on a new generation of the GaAs based long-wavelength laser device. Recently they have developed the world's first 1.586μm GaInNAsSb/GaNAs/GaAs single quantum well laser diode under continuous-wave operation mode at room temperature.
As a result of rapid development of the processing amount of data information through internet in recent years, the demands for high-speed and large-capacity optical-fibre telecommunication networks are going up drastically. In comparison with InP-based laser devices now available on the market, the GaAs-based near infrared materials feature a lower cost, better characteristic temperatures, stable properties and simpler photonic integration. So they become ideal for developing the new generation of multi-purpose opto-electronic devices. However, extending GaInNAs(Sb) beyond 1.4μm has become a challenging task due to a the large number of defects created while growing these highly strained metastable alloys with high nitrogen contents.
With the support from the several national and CAS S&T programs, a joint research group headed by Dr. NIU Zhichuan at the National Laboratory for Superlattice and Microstructure and the State Key Laboratory for Integrated Opto-electronics affiliated to ISCAS has been successful in developing a GaInAsN(Sb)/GaNAs/GaAs quantum welledge emitting laser diode at 1.586 μm under continuous-wave operation at room temperature.
The researchers started their work on the successful development of 1.3μm GaInNAs/GaAs quantum wells grown by molecular beam epitaxy technique. Through optimization of Nitrogen incorporation amount and introducing Sb element and overlapped layers of GaNAs, the emitting wavelength of GaInNAsSb/GaNAs/GaAs quantum wells was expanded up to 1.586 μm. At the same time, annealing processing was carried out so that the crystal quality of the quantum well was greatly improved and reached the technical requirements for making the laser diode.
This is the first report of a GaAs based laser diode with lasing wavelength longer than 1.55μm at room-temperature under continuous wave operation. Its performances, such as threshold current density less than 2.6kA/cm2 and the output power higher than 30mw, demonstrated better results than the studies of GaAs based 1.5μm devices reported from other internationl groups. The success proves the feasibility for all-round application of the GaAs-based long wavelength devices to the waveband between 1.2μm and 1.6μm, presenting a bright prospect in the application and industrialization of the devices in optical telecommunications.
