1.3 µm lasing of circular defect cavity photonic crystal laser with an AlO<i>_x</i> cladding layer

Abstract

We fabricated a photonic crystal (PC) laser having a circular defect cavity and a line defect output waveguide based on a heterostructure consisting of a slab layer with quantum dots and an AlO x cladding layer. The photonic crystal laser was excited by a 785 nm laser diode. Samples with different parameters have similar threshold values of about 25 µm Roomtemperature continuous-wave lasing operation at 1.3 µm range is confirmed by observing the spectrum of output light from the line defect waveguide. The wavelengths of the lasing modes show the dependence on the radius of circular resonator and the radius of air holes, which indicate that the lasing mode is the whispering-gallery mode. These results show the feasibility of realizing PC lasers using AlO x cladding layers.

Photonic Crystal Circular Defect (CirD) Laser

“…This value is as large as 10 times the calculated Q.) The threshold current of the electrically-driven CirD laser was estimated to be 4 µA [25], which agrees with the result calculated by rate equations (Figure 6). The output intensity increases with the increasing of excitation power up to about 1 mW without saturation.…”

“…Figure 9 shows a typical excitation power versus output intensity curve of the CirD laser (a = 345 nm, R = 2.76 a, r = 0.31 a). Threshold excitation power P th was estimated as small as approximately 25 µW, which was almost constant even if the structure parameters of the CirD laser were modified [25]. This indicates that optically-driven CirD lasers have sufficiently high Q because the threshold hardly varies when Q is larger than 2000 ( Figure 6).…”

“…Air holes with minor contractions, etched on an epitaxial wafer with InAs QDs layers by using a multistep etching recipe, were obtained since we achieved a good balance between the physical and the chemical etching effects for the core layer [31]. The wavelength tuning of the CirD lasers was demonstrated using optical pumping technology [25,26]. To relax the requirements of the dry etching process, we employed a structure without a GaAs contact and upper cladding layers.…”

“…Fabrication of samples and measurement set-up can be found in the references [25,26]. All experiments were conducted under RT-CW conditions.…”

“…We previously proposed a novel electrically-driven PhC laser structure [24] called the CirD laser since a circular-defect cavity that forms a whispering gallery mode (WGM) along the cavity boundary is used to generate the laser light in this structure [25]. By simultaneously employing two AlGaAs/AlGaO x cladding layers, CirD lasers enable RT-CW operation through vertical current injection.…”