Abstract
Planar broad-area single-mode lasers, with modal widths of the order of tens of microns, are technologically important for high-power applications and improved coupling efficiency into optical fibers. They may also find new areas of applications in on-chip integration with devices that are of similar size scales, such as for spectroscopy in microfluidic chambers or optical signal processing with micro-electromechanical systems. An outstanding challenge is that broad-area lasers often require external means of control, such as injection-locking or a frequency/spatial filter to obtain single-mode operation. In this paper, we propose and demonstrate effective index-guided, large-area, edge-emitting photonic crystal lasers driven by pulsed electrical current injection at the optical telecommunication wavelength of 1550 nm. By suitable design of the photonic crystal lattice, our lasers operate in a single mode with a 1/e(2) modal width of 25 microm and a length of 600 microm.
Highlights
For more than three decades, structures with spatially periodic dielectric constants have played a crucial role in engineering the propagation and confinement of optical waves [1]
We describe photonic crystal lasers with low index contrast that operate under a pulsed electrical current injection
The refractive index contrast between the etched hole and unetched region is on the order of 10 −2, which is about two orders of magnitude smaller than conventional photonic crystals and two orders of magnitude larger than a single-mode step-index waveguide of comparable dimensions
Summary
For more than three decades, structures with spatially periodic dielectric constants have played a crucial role in engineering the propagation and confinement of optical waves [1]. Most on-chip photonic crystal lasers to date use Bragg reflection to select the lasing mode and are vertically emitting. Pumped semiconductor photonic crystal lasers with Bragg-guided modes have been demonstrated in surface emitting structures with both low index contrast [5] and high index contrast [7]. In our previous work [8], we have shown some preliminary results of electrically pumped, edge-emitting semiconductor lasers with cross defects based on Bragg-guided modes. We describe photonic crystal lasers with low index contrast that operate under a pulsed electrical current injection. These are edge-emitting devices and are well-suited for planar integration. In contrast to conventional distributed feedback (DFB) lasers, the lasing mode frequency is away from the Brillouin zone edge of the photonic crystal [11],[12]
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