MEMS Laser with Tunable Wavelength and Polarization using Optical Tunneling Effect

This paper presents a micromachined tunable laser that utilizes a silicon optical tunneling structure to tune both the polarization state and the wavelength of the laser output. The device is fabricated on silicon-on-insulator wafer using deep reactive ion etching. In experiment, the wavelength and the polarization are tuned by heating up the silicon optical tunneling structure via the thermo-optic effect. A 90deg change of polarization direction is obtained using a heating current of 61.2 mA, and a wavelength tuning of 2 nm is also demonstrated. The output spectrum shows a high suppress ratio above 30 dB. Compared with the previous MEMS tunable lasers that have a random or fixed polarization state, this device provides a special capability in tuning the polarization state in addition to the wavelength, and would find niche applications in biomedical research, interferometry, coherent communications, instrumentations and sensors.