III-V laser on silicon chip has micro-loop mirror

A scanning-electron-microscope image shows the silicon-based micro-loop mirror (MLM). Light entering the waveguide from the left is guided around the loop and redirected back into the laser structure. The inset shows the laser spot photographed with an IR camera. (Copyright: A*STAR)

Singapore--A group at the A*STAR Data Storage Institute has fabricated electrically pumped III-V semiconductor lasers and novel cavity mirrors on top of silicon chips -- a step forward for optical data interconnects.1 The laser cavity consists of silicon-on-insulator (SOI) waveguides and passive SOI so-called micro-loop mirrors (MLMs) with 98% reflectivity. The laser emits single-mode, continuous-wave light at room temperature with a lasing threshold current density of 2.5 kA/cm2.

Active optical fibers with silicon-photonic chips can carry much more information for data interconnects than copper cables. Silicon photonics can also be the material of choice for wiring "lab-on-a-chip" devices. One of the greatest difficulties, however, is the implementation of lasers, because silicon is such a poor light emitter.

“Integrated Si/III-V lasers can take advantage of low-loss silicon waveguides, while addressing the problem of low light-emission efficiency that silicon devices typically have,” says Doris Keh-Ting Ng, one of the A*STAR researchers.

Attaching a Si/III-V laser on top of silicon requires challenging fabrication techniques, and device performances can suffer as a result. Furthermore, any laser requires mirrors to maintain lasing action. Such designs typically rely on the interface between air and the semiconductor facets.; however, such mirrors are not perfect and further reduce operation efficiency.

To improve on the latter aspect, the researchers came up with the MLM design. Light emitted from one end of the laser is guided along the waveguide, around a narrow bend, and then back into the device (see figure). The mirror at the other end of the device is still formed by the interface with air so that laser radiation can exit the device.

More than 30 delicate, high-precision fabrication steps are needed to fabricate the device. The researchers aim to further enhance the laser by miniaturizing the device.

“Further improvements, for example, at the interface between the mirror and the lasing structure itself, could lead to even better performance,” says Ng. “A laser with lower threshold and higher output power can possibly be achieved, leading to a potential solution to develop high-speed and low-cost optical communications and interconnects on electronics chips.”


Yunan Zheng et al., Applied Physics Letters 99, 011103 (2011).

Get All the Laser Focus World News Delivered to Your Inbox

Subscribe to Laser Focus World Magazine or email newsletter today at no cost and receive the latest news and information.

 Subscribe Now

Most Popular Articles

White Papers

Tailored bar concepts for 10 mm-mrad fiber coupled modules scalable to kW-class direct diode lasers

In this paper, laser modules based on newly developed tailored bars are presented. The modules al...

Wavelength stabilized multi-kW diode laser systems

Wavelength stabilization of high-power diode laser systems is an important means to increase the ...

Optical Isolators Improve Engraving Performance of Pulsed Fiber Lasers

The deleterious effects of back reflections on pulsed fiber lasers used in marking and engraving ...
Technical Digests
There is no current content available.

Click here to have your products listed in the Laser Focus World Buyers Guide.


AFL Introduces New Family of NYFORS™ Recoating Products

10/03/2013 AFL now offers Nyfors Teknologi AB’s new family of recoating products including the ReCoater 2™, ...

AFL Rebrands Optimal Cable Services

10/03/2013 AFL began its rebrand of Optimal Cable Services, a manufacturer of fiber optic cable and provider...

Vytran Introduces Compact Automated Optical Fiber Cleavers for High-Volume Manufacturing

09/25/2013 Vytran introduces the “CAC-400” and the “CAC-400-A”—compact, automated, large-diameter optical fi...

Vytran to Highlight Optical Fiber Processing Solutions for Fiber Laser Production and Others at CLEO: 2013

06/05/2013 Vytran will emphasize its tools and techniques for creating optical fiber splices and fused-fiber...
Social Activity
Copyright © 2007-2014. PennWell Corporation, Tulsa, OK. All Rights Reserved. PRIVACY POLICY | TERMS AND CONDITIONS