Abstract
Dopants in silicon (Si) have attracted attention in the fields of photonics and quantum optics. However, the optical characteristics are limited by the small spontaneous emission rate of dopants in Si. This study demonstrates a large increase in the spontaneous emission rate of copper isoelectronic centres (Cu-IECs) doped into Si photonic crystal nanocavities. In a cavity with a quality factor (Q) of ~16,000, the photoluminescence (PL) lifetime of the Cu-IECs is 1.1 ns, which is 30 times shorter than the lifetime of a sample without a cavity. The PL decay rate is increased in proportion to Q/Vc (Vc is the cavity mode volume), which indicates the Purcell effect. This is the first demonstration of a cavity-enhanced ultrafast spontaneous emission from dopants in Si, and it may lead to the development of fast and efficient Si light emitters and Si quantum optical devices based on dopants with efficient optical access.
Highlights
Correspondence and requests for materials should be addressed to Ultrafast spontaneous emission of copper-doped silicon enhanced by an optical nanocavity
We found that only one study has reported a small increase (70 percent) in the PL decay rate of Si nanocrystals embedded in a microdisk cavity it is difficult to distinguish the radiative decay rate increase by the Purcell effect from the nonradiative decay increase induced by fabrications[22]
These results show that our doping method successfully creates Cu-IECs in the thin Si films and enables us to fabricate Si photonic crystal (PhC) nanocavities containing the Cu-IECs
Summary
Correspondence and requests for materials should be addressed to Ultrafast spontaneous emission of copper-doped silicon enhanced by an optical nanocavity. If the emission linewidth of the dopants is smaller than the cavity linewidth, the Purcell enhancement of the emission rate is proportional to Q/Vc, where Q and Vc are the quality factor and the mode volume of the optical cavity, respectively[15] This means that the high Q and small Vc of nanocavities make it possible to obtain a large increase in the emission rate of radiative centres doped in Si. The Purcell effect is especially pronounced in Si photonic crystal (PhC) nanocavities because ultrafine Si processes enable us to fabricate Si PhC nanocavities with a high Q of over 106 and an ultrasmall Vc of less than 0.1 mm . To obtain clear evidence of the Purcell effect, a simultaneous increase in the PL intensity and PL decay rate should be observed while nonradiative processes are carefully considered
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