Spontaneous emission extraction and Purcell enhancement from thin-film 2-D photonic crystals

Abstract

Electromagnetic band structure can produce either an enhancement or a suppression of spontaneous emission from two-dimensional (2-D) photonic crystal thin films. We believe that such effects might be important for light emitting diodes. Our experiments were based on thin-film InGaAs/InP 2-D photonic crystals at ambient temperature, but the concepts would apply equally to InGaN thin films, for example. We show that the magnitude of Purcell enhancement factor, F F F p p p 2, for spatially extended band modes, is similar to that for a tiny mode in a three-dimensional (3-D) nanocavity. Nonetheless, light extraction enhancement that arises from Zone folding or Bragg scattering of the photonic bands is probably the more important effect, and an external quantum efficiency >50% is possible. Angle resolved photoluminescence from inside the photonic crystal gives a direct spectral readout of the internal 2-D photonic band dispersion. The tradeoffs for employing various photonic crystal structures in high efficiency light-emitting diodes are analyzed.

Nanophotonic luminescent solar concentrators

“…The bilayer slab (Fig.2a) LDOS is approximately 80% of the n = 1.7 conventional LSC, consistent with previous experimental and theoretical work on dielectric slabs [26]. The PC-LSC LDOS (Fig.2b) falls between that of n = 1.5 and n = 1.7 conventional LSCs, but does not exceed the n = 1.7 conventional LSC [24]. The TE-like (blue) and TM-like (red) contributions to the total LDOS confirm that the LDOS enhancement lies at the Van Hove singularity corresponding to the M -point (Fig.…”

“…The maximum TIR LDOS enhancement of spontaneous emission is limited by lumophore photoluminescence spectrum linewidth (Q m = ω 0 /∆ω) to Q m /4f tir [24]. LSC lumophore Q m -factors range from three to seven for organics (Fig.…”

Separation of radiation and absorption losses in two-dimensional photonic crystal single defect cavities

“…The characterization of 2D photonic crystals has been made mostly by measuring the spectrum of photoluminescence 4,5,13 and electroluminescence. 14 These techniques are useful and relatively easy to perform due to the fact that the light is generated inside the cavity.…”

Micro-Optical Resonators for Microlasers and Integrated Optoelectronics

“…In wavelength-sized microresonator structures, semiconductor material luminescence can be either suppressed or enhanced, and they also enable narrowing of the spectral linewidth of the emitted light (Haroche, 1989;Yokoyama, 1992;Yamamoto, 1993;Vahala, 2003). Since 1946, when it was first proposed that the spontaneous emission from an excited state of an emitter can be significantly altered if it is placed into low-loss wavelength-scale cavity (Purcell, 1946), various microresonator designs for efficient control of spontaneous emission have been explored including microdisk Baba, 1997Baba, , 1999Backes, 1999;Cao, 2000;Fujita, 1999Fujita, , 2001Fujita, , 2002Zhang, 1996), microsphere Shopova, 2004;Rakovich, 2003) and micropost (Pelton, 2002;Reithmaier, 2004;Santori, 2004;Solomon, 2001;Gayral, 1998) resonators as well as PC defect cavities Boroditsky, 1999;Gayral, 1999). Depending on the Q-factors (resonance linewidths) of the modes supported by the microresonator in the spontaneous emission range of the resonator material, the two situations illustrated in Fig.…”

“…2c), formed, e.g., as arrays of air holes etched into a slab, have been demonstrated to simultaneously exhibit high Q-factors and ultra-small, wavelength-scale modal volumes Benisty, 1999;Chow, 2000;Yoshie, 2001;Akahane, 2003;Srinivasan, 2004;Noda, 2000;Boroditsky, 1999). In these cavities, the photonic-bandgap effect (fulfilment of the Bragg reflection conditions for all the propagation directions in a certain frequency range) is used for strong light confinement in the cavity plane, and TIR, for light confinement at the air-slab interface (Russel, 1996;.…”