MEMS Structures Used to Injection-Lock Miniature Laser
In the Sept. 5 issue of Applied Physics Letters, investigators at Nanyang Technological University in Singapore report the development of a 3 × 2 × 0.6-mm injection-locked InGaAsP/InP laser system that incorporates microelectromechanical systems (MEMS) technology. Such lasers, they suggest, may have applications in optical switching for telecommunications and in portable atomic clocks.
A scanning electron micrograph of the laser system (left) reveals the design of the setup. The structure at center is the external-cavity master laser, the output of which can be tuned over a range of 30.3 nm using a MEMS blazed grating in the Littrow configuration. At the left of center is the multimode Fabry-Perot slave laser. Between them, a 55 × 20 × 35-µm silicon right-angle prism with an acute angle of 20° attached to an electrostatic comb actuator is meant to serve as an optical isolator and to provide active alignment and variable attenuation between the master and slave lasers.
Ai Qun Liu, an associate professor of electrical and electronic engineering at the university, noted that the researchers currently are reviewing the performance of the prism as an isolator.
In their experiments, the scientists confirmed that the slave laser was injection-locked at 1534.72 nm, with a side mode suppression ratio of 55 dB. When the signal from the master laser was pulsed at 1 MHz and an additional 50-MHz signal — 1.6 dB weaker than that from the master — also was injected, the side mode suppression ratio was 42.8 dB, and the slave demonstrated a switching rate of up to 100 MHz.
- microelectromechanical systems (mems)
- Refers to micron-size complex machines that have physical dimensions suitable for the fabrication of optical switches for use in state-of-the-art communications networks.
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