Efficient 1535 nm light emission from an all-Si-based optical micro-cavity containing Er^3+ and Yb^3+ ions

Abstract

This work reports on the construction and spectroscopic analyses of optical micro-cavities (OMCs) that efficiently emit at ~1535 nm. The emission wavelength matches the third transmission window of commercial optical fibers and the OMCs were entirely based on silicon. The sputtering deposition method was adopted in the preparation of the OMCs, which comprised two Bragg reflectors and one spacer layer made of either Er-or ErYb-doped amorphous silicon nitride. The luminescence signal extracted from the OMCs originated from the 4 I 13/2 → 4 I 15/2 transition (due to Er 3+ ions) and its intensity showed to be highly dependent on the presence of Yb 3+ ions. According to the results, the Er 3+ -related light emission was improved by a factor of 48 when combined with Yb 3+ ions and inserted in the spacer layer of the OMC. The results also showed the effectiveness of the present experimental approach in producing Si-based light-emitting structures in which the main characteristics are: (a) compatibility with the actual microelectronics industry, (b) the deposition of optical quality layers with accurate composition control, and (c) no need of uncommon elementscompounds nor extensive thermal treatments. Along with the fundamental characteristics of the OMCs, this work also discusses the impact of the Er 3+ −Yb3+ ion interaction on the emission intensity as well as the potential of the present findings.

Enhancement of 1.5 μm emission under 980 nm resonant excitation in Er and Yb co-doped GaN epilayers

“…However, the observed enhancement in the 1.5 lm emission efficiency in MOCVD grown Er þ Yb:GaN epilayers over Er:GaN epilayers is consistent with the expected sensitization effect. 24,[27][28][29][30][31] A low thermal quenching of 20% in the 1.54 lm emission from 10 to 300 K has been previously observed in the Er:GaN epilayers for an above bandgap excitation (k exc ¼ 263 nm). 12 A band-to-band excitation can excite both the isolated RE centers as well as defect-related RE optical centers.…”

“…It has been well established that Er and ytterbium (Yb) co-doping in a solid host is an effective approach to enhance the Er emission at 1.5 lm under 980 nm resonant excitation. 24,[27][28][29][30][31] This is due to the fact that the absorption cross section of Yb 3þ at 980 nm is about one order of magnitude larger than that of Er 3þ . In the Er and Yb co-doped materials, Yb 3þ ions act as sensitizers by absorbing 980 nm excitation photons and then transferring energy resonantly from their excited 2 F 5/2 state to the 4 I 11/2 level of Er 3þ ions.…”

“…In the Er and Yb co-doped materials, Yb 3þ ions act as sensitizers by absorbing 980 nm excitation photons and then transferring energy resonantly from their excited 2 F 5/2 state to the 4 I 11/2 level of Er 3þ ions. 24,[27][28][29][30][31] This efficient resonant energy transfer process is facilitated by the close match between the energy levels of the 2 F 5/2 state of Yb 3þ and the 4 I 11/2 state of Er 3þ . This transfer is then followed by a rapid nonradiative decay to the first 4 I 13/2 excited manifold of Er 3þ ions, after which a direct transition to the 4 I 15/2 ground state of Er 3þ occurs, resulting in the 1.5 lm emission.…”

“…31 The incorporation of Yb at a doping level similar to that of Er is thus expected to provide a nearly one order of magnitude enhancement in the effective optical absorption efficiency at 980 nm and hence a higher emission efficiency at 1.5 lm. 31 Different methods have been employed to obtain Er and Yb co-doped semiconductors so far, including magnetron sputtering 27,28 and ion-implantation. 29 Compared to these methods, in-situ co-doping of Er and Yb via epitaxial growth has the advantages of providing a more uniform distribution of RE concentrations and reduced impact to the crystalline quality of the host crystals; 30 however, this had not been previously attempted in GaN.…”

“…The expected major benefit of Yb and Er co-doping is the enhancement of the absorption efficiency at 980 nm via the sensitization effect. 24,[27][28][29][30][31] The room temperature PL spectra of the same set of Er þ Yb:GaN epilayers grown under varying Yb flow rates from 0 to 2.4 SLM and a fixed Er flow rate of 2.2 SLM were measured under 980 nm resonant excitation, and the results are presented in Fig. 4(a).…”