Electrically-pumped, broad-area, single-mode photonic crystal lasers

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 1550nm. By suitable design of the photonic crystal lattice, our lasers operate in a single mode with a 1/e 2 modal width of 25μm and a length of 600μm .

Continuous-wave operation of electrically pumped, single-mode, edge-emitting photonic crystal Bragg lasers

“…These structures have been engineered to make large-modal-volume, high-power semiconductor lasers with narrow spectral linewidths and narrow beam divergences. [1][2][3][4][5][6][7] We have recently reported electrically pumped, large-area, edge-emitting photonic crystal Bragg lasers operating in pulsed condition. 7 Furthermore, we demonstrated that we could systematically tune the lasing wavelength by changing the PC lattice constants, thus demonstrating that the lasing mode is truly defined by both the longitudinal and transverse Bragg conditions.…”

Electrically pumped edge-emitting photonic crystal lasers with angled facets

“…We have recently demonstrated single-mode lasing based on effective index guiding for on-chip photonic crystal lasers. 2 For Bragg-guided modes, light is confined by Bragg reflection arising from a photonic bandgap in the transverse direction. Lasing with Bragg-guided modes can be designed to maintain a near-diffraction-limited far field for largearea edge-emitting semiconductor lasers even at relatively high powers.…”

“…2 The photonic crystal structure is first written on the wafer surface by electron-beam lithography and is then etched into the semiconductor for ϳ360 nm to obtain the desired index contrast. The polyimide planarization is realized by an etch-back process and creates a polyimide post inside each etched hole.…”

Spatial modal control of two-dimensional photonic crystal Bragg lasers

“…The metal contact width is about 100 m and the facet tilt angle is 13.2°. Detailed fabrication procedures can be found in [8][9][10]. Figure 1(b) shows the cross-section structure of a fabricated PC Bragg laser.…”

“…We first use a transfer matrix model [10,11] to compare different order transverse modes of the PC Bragg laser and find that only the first-order (fundamental) TBR mode has a single-lobed near field and thus a single-lobed far field. We show that the transverse coupling coefficient determines the intermodal discrimination between the fundamental and high-order TBR modes and there exists a trade-off between ensuring lasing in the fundamental TBR mode and reducing the threshold.…”