Appl. Phys. Lett. 113, 201105 (2018)

The ability to tune the wavelength of a laser over a broad spectral range is desirable for many photonics applications. Now, Xiaowei Wang and co-workers from the USA demonstrate room-temperature, efficient, wide tuning of 250 nm using tensile-strained nanomembranes of InGaAs, a popular active material for making infrared diode lasers. The nanomembrane is formed by a 100-nm-thick InGaAs film grown by molecular beam epitaxy and lattice-matched to an InAlAs layer on InP. After fabrication, a thin layer of photoresist is spin-coated onto the InGaAs film and the film is subsequently released from the underlying sacrificial materials resulting in a free-standing membrane. The nanomembrane has lateral dimensions of about 5 × 5 mm2 and is bonded to a 125-μm-thick flexible film of polyimide. It is mounted on a rigid cell that is pressurized with a controlled gas flow to introduce biaxial tensile strain. The team measured a large red shift in the peak light emission from 1,650 nm to 1,900 nm at the highest measured pressure of 620 kPa that caused a biaxial tensile strain of over 1.1%.