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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 11 — Jun. 3, 2013
  • pp: 13479–13491
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Plasmonic gap-mode nanocavities with metallic mirrors in high-index cladding

Pi-Ju Cheng, Chen-Ya Weng, Shu-Wei Chang, Tzy-Rong Lin, and Chung-Hao Tien  »View Author Affiliations


Optics Express, Vol. 21, Issue 11, pp. 13479-13491 (2013)
http://dx.doi.org/10.1364/OE.21.013479


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Abstract

We theoretically analyze plasmonic gap-mode nanocavities covered by a thick cladding layer at telecommunication wavelengths. In the presence of high-index cladding materials such as semiconductors, the first-order hybrid gap mode becomes more promising for lasing than the fundamental one. Still, the significant mirror loss remains the main challenge to lasing. Using silver coatings within a decent thickness range at two end facets, we show that the reflectivity is substantially enhanced above 95 %. At a coating thickness of 50 nm and cavity length of 1.51 μm, the quality factor is about 150, and the threshold gain is lower than 1500 cm−1.

© 2013 OSA

1. Introduction

There has been significant progress in miniaturized semiconductor lasers beyond the diffraction limit [1

1. J. A. Schuller, E. S. Barnard, W. Cai, Y. C. Jun, J. S. White, and M. L. Brongersma, “Plasmonics for extreme light concentration and manipulation,” Nature Mater. 9, 193–204 (2010) [CrossRef] .

3

3. R. M. Ma, R. F. Oulton, V. J. Sorger, and X. Zhang, “Plasmon lasers: coherent light source at molecular scales,” Laser & Photon. Rev. 7, 1–21 (2013).

]. With advantages such as ultrasmall light spots and fast switching, plasmonic nanolasers have potential applications in biochemical sensing [4

4. M. Lončar, A. Scherer, and Y. Qiu, “Photonic crystal laser sources for chemical detection,” Appl. Phys. Lett. 82, 4648–4650 (2003) [CrossRef] .

], imaging [5

5. Y. Nakayama, P. J. Pauzauskie, A. Radenovic, R. M. Onorato, R. J. Saykally, J. Liphardt, and P. Yang, “Tunable nanowire nonlinear optical probe,” Nature 447, 1098–1101 (2007) [CrossRef] [PubMed] .

], and short-distance optical interconnects [6

6. R. G. Beausoleil, P. J. Kuekes, G. S. Snider, S. Y. Wang, and R. S. Williams, “Nanoelectronic and nanophotonic interconnect,” Proc. IEEE 96, 230–247 (2008) [CrossRef] .

]. Despite the high loss accompanying the small cavity size achieved experimentally [7

7. M. T. Hill, Y. S. Oei, B. Smalbrugge, Y. Zhu, T. de Vries, P. J. van Veldhoven, F. W. M. van Otten, T. J. Eijkemans, J. P. Turkiewicz, H. de Waardt, E. J. Geluk, S. H. Kwon, Y. H. Lee, R. Nötzel, and M. K. Smit, “Lasing in metallic-coated nanocavities,” Nat. Photonics 1, 589–594 (2007) [CrossRef] .

19

19. K. J. Russell and E. L. Hu, “Gap-mode plasmonic nanocavity,” Appl. Phys. Lett. 97, 163115 (2010) [CrossRef] .

], metals may also serve as a multi-functional medium for reflectors, electrical injectors, and heatsinks [20

20. C. Y. Lu, S. W. Chang, S. L. Chuang, T. D. Germann, U. W. Pohl, and D. Bimberg, “Low thermal impedance of substrate-free metal cavity surface-emitting microlasers,” IEEE Photon. Technol. Lett. 23, 1031–1033 (2011) [CrossRef] .

]. Recently, Russell et al. have demonstrated a gap-mode plasmonic nanocavity consisting of a metallic nanowire and dielectric/metal planar structure [18

18. K. J. Russell, T. L. Liu, S. Cui, and E. L. Hu, “Large spontaneous emission enhancement in plasmonic nanocavities,” Nat. Photonics 6, 459–462 (2012) [CrossRef] .

, 19

19. K. J. Russell and E. L. Hu, “Gap-mode plasmonic nanocavity,” Appl. Phys. Lett. 97, 163115 (2010) [CrossRef] .

]. In analogy to the active dielectric nanowire [21

21. R. F. Oulton, V. J. Sorger, D. A. Genov, D. F. P. Pile, and X. Zhang, “A hybrid plasmonic waveguide for sub-wavelength confinement and long-range propagation,” Nat. Photonics 2, 496–500 (2008) [CrossRef] .

, 22

22. P. J. Cheng, C. Y. Weng, S. W. Chang, T. R. Lin, and C. H. Tien, “Cladding effect on hybrid plasmonic nanowire cavity at telecommunication wavelengths,” IEEE J. Sel. Top. Quantum Electron. 19, 4800306 (2013) [CrossRef] .

], the dielectric slab in their work can play the role of gain medium. Although metallic nanowires introduce the higher absorption than dielectric counterparts do, the experiment indicates that the cavity quality (Q) factor and threshold gain (gth) of this type of cavities are mainly limited by the mirror loss at end facets rather than the propagation loss from metallic components [19

19. K. J. Russell and E. L. Hu, “Gap-mode plasmonic nanocavity,” Appl. Phys. Lett. 97, 163115 (2010) [CrossRef] .

].

In this paper, we analyze a three-dimensional (3D) plasmonic Fabry-Perot (FP) nanolaser based on surface-plasmon-polariton (SPP) gap modes at telecommunication wavelengths around 1.55 μm. The proposed configuration is composed of a truncated waveguide formed by a silver (Ag) nanowire and Ag substrate which sandwich a low-index dielectric gap of silicon dioxide (SiO2), as indicated in Fig. 1(a). The dielectric gap plays the role of active regions and contains colloidal quantum dots (QDs) as the gain medium [23

23. J. Grandidier, G. C. des Francs, S. Massenot, A. Bouhelier, L. Markey, J.-C. Weeber, C. Finot, and A. Dereux, “Gain-assisted propagation in a plasmonic waveguide at telecom wavelength,” Nano Lett. 9, 2935–2939 (2009) [CrossRef] [PubMed] .

, 24

24. D. Dai, Y. Shi, S. He, L. Wosinski, and L. Thylen, “Gain enhancement in a hybrid plasmonic nano-waveguide with a low-index or high-index gain medium,” Opt. Express 19, 12925–12936 (2011) [CrossRef] [PubMed] .

]. The structure is covered by a thick cladding layer, and two Ag-coated end facets function as reflectors, as shown in Fig. 1(b). The refractive index nc of the cladding will be varied in later calculations under different gap heights h and wire radii r. To model open regions outside two reflectors and extended cladding layers, we utilize perfectly matched layers (PMLs) around the cavity for practical calculations. We are particularly interested in the case of nc = 3.5 because it corresponds to the deposition of semiconductors as the cladding layer. In this way, the technologies of silicon photonics and microelectronics, including group-IV and III–V semiconductors [25

25. M. Ozeki, “Atomic layer epitaxy of III–V compounds using metalorganic and hydride sources,” Mater. Sci. Rep. 8, 97–146 (1992) [CrossRef] .

27

27. D. P. Arnold, F. Cros, I. Zana, D. R. Veazie, and M. G. Allen, “Electroplated metal microstructures embedded in fusion-bonded silicon: conductors and magnetic materials,” J. Microelectromech. Syst. 13, 791–798 (2004) [CrossRef] .

], may be further integrated with plasmonics and bring about more functionalities.

Fig. 1 (a) A metallic nanowire is separated from the Ag substrate by the active layer. The structure is embedded in a cladding layer. (b) The side view of the plasmonic gap-mode nanocavity. In practical calculations, the extended regions are surrounded by PMLs.

A high cladding refractive index, nevertheless, affects the characteristics of lasing modes. In fact, the cross-sectional profile of the FP lasing mode at a low cladding index is not identical to that at a high index. The fundamental transverse mode of the guiding structure in Fig. 1 is the most promising for lasing at a low cladding index [22

22. P. J. Cheng, C. Y. Weng, S. W. Chang, T. R. Lin, and C. H. Tien, “Cladding effect on hybrid plasmonic nanowire cavity at telecommunication wavelengths,” IEEE J. Sel. Top. Quantum Electron. 19, 4800306 (2013) [CrossRef] .

]. In the high-index condition, however, the first-order mode often exhibits the better field confinement in the active region than the fundamental one does. Thus, rather than the fundamental guided mode which is usually the focus in typical FP cavities, we look into the first-order mode in the presence of high-index cladding materials such as semiconductors.

2. Analysis of modal characteristics

The SPP gap modes of the cavity structure in Fig. 1 are formed by the coupling between plasmonic modes of the circular Ag nanowire and surface waves of the active layer sandwiched by the Ag substrate and cladding. The coupling strengths between these two categories of modes are sensitive to variations of parameters such as the cladding index nc, gap height h, and wire radius r[21

21. R. F. Oulton, V. J. Sorger, D. A. Genov, D. F. P. Pile, and X. Zhang, “A hybrid plasmonic waveguide for sub-wavelength confinement and long-range propagation,” Nat. Photonics 2, 496–500 (2008) [CrossRef] .

]. Depending on the parameters, the features of one type of modes may dominate those of the other type and vice versa. In the following analysis, we set the refractive index nm of Ag to 0.16 + 11.09i[30

30. P. B. Johnson and R. W. Christy, “Optical constants of the noble metals,” Phys. Rev. B 6, 4370–4379 (1972) [CrossRef] .

] and counterpart na of SiO2 to 1.5 at the wavelength of 1.55 μm. Calculations are conducted with the 2D FEM eigenmode solver of the software COMSOL [31

31. COMSOL Multiphysics, http://www.comsol.com.

].

When a circular metallic cylinder (Ag nanowire in the cavity structure of interest) is adjacent to a dielectric gap layer atop the metallic substrate, the rotational symmetry is broken, and guided modes of the cylinder are strongly coupled to surface plasmon modes localized near/within the dielectric gap through evanescent fields from the two parts. This coupling leads to plasmonic gap modes in the composite guiding structure. For the circular metallic cylinder in a homogeneous dielectric, the TM0 guided mode (azimuthal mode number m = 0) is a non-cutoff, circularly symmetric one with the maximal field strength localized around the circumference. On the other hand, the two degenerate first-order modes HE±1 (m = 1) on the circular cross section correspond to parallel (+1) and normal (−1) free charge oscillations to the planar structure [32

32. S. Zhang and H. Xu, “Optimizing substrate-mediated plasmon coupling toward high-performance plasmonic nanowire waveguides,” ACS Nano 6, 8128–8135 (2012) [CrossRef] [PubMed] .

]. As the metallic cylinder is in the proximity to a flat plane, the guided modes TM0 and HE−1 are hybridized and mixed with gap modes of the planar structure. For the whole guiding structure, if there is considerable field strength distributed in the cladding, the fundamental hybrid gap mode exhibits characteristics of the TM0 mode, while the first-order one carries features of the HE−1 mode with a dominant field normal to the planar structure.

In Fig. 2, we show square magnitudes |E(ρ)|2 of the cross-sectional profiles (ρ = xx̂+ is the transverse coordinate) for the fundamental and first-order modes at h = 10 nm, r = 70 nm, and nc = 1, 2.5 and 3.5. The corresponding effective indices are 2.24 + 0.014i [inset in Fig. 2(a)], 3.31 + 0.020i, 4.10 + 0.022i, 2.55 + 0.004i, and 3.54 + 0.018i [Fig. 2(a) to (d)], respectively. From the inset in Fig. 2(a), the fundamental mode at nc = 1 (< na = 1.5) is localized near the bottom of the nanowire, which is similar to the localized field near tips of metallic bowtie structures [33

33. T. R. Lin, S. W. Chang, S. L. Chuang, Z. Zhang, and P. J. Schuck, “Coating effect on optical resonance of plasmonic nanobowtie antenna,” Appl. Phys. Lett. 97, 063106 (2010) [CrossRef] .

]. The localized field below the wire bottom does not penetrate into the active region much. At nc = 2.5 [Fig. 2(a)], in contrast, the field of the fundamental hybrid gap mode is tightly confined in the active region below the nanowire and does not spread around lossy regions of the Ag nanowire and substrate. Such an advantage for lasing is, nevertheless, absent in the target case of nc = 3.5 (semiconductors) because the nature of TM0 mode emerges on the mode profile, as can be observed from the field strength which is quite circularly symmetric near the nanowire in Fig. 2(b). Under such circumstances, the poorer field confinement in the active region and more significant distribution around the Ag nanowire makes the fundamental mode less promising for lasing in the presence of semiconductor claddings.

Fig. 2 Square magnitudes |E(ρ)|2 of the cross-sectional profiles for the fundamental mode at (a) nc = 2.5 (inset: nc = 1) and (b) nc = 3.5, and for the first-order mode at (c) nc = 2.5 and (d) nc = 3.5. The height h and radius r are 10 and 70 nm, respectively. At nc = 3.5, the first-order mode is better confined in the active region than the fundamental one is.

The field evolution of the first-order mode proceeds with a reverse trend to that of the fundamental one as nc increases. At ncna, the first-order mode is a leaky one with the majority of the field distributed in the free space outside the Ag nanowire, dielectric gap, and substrate. As soon as nc > na, the mode begins to localize around the Ag nanowire and active region. From Fig. 2(c), the nature of HE−1 modes at nc = 2.5 is reflected on the field partially distributed near the upper half of the nanowire and within the active region. On the other hand, from Fig. 2(d), at nc = 3.5, the feature of HE−1 modes becomes much more prominent. The lower lobe of HE−1 modes closely overlaps with the gap mode of the planar structure. Accordingly, at this cladding index, the first-order mode is tightly confined inside the active gap, which is promising for lasing. Therefore, if we would pick up a cross-sectional profile for the lasing mode with semiconductor claddings, the first-order mode should be the choice.

Fig. 3 (a) The waveguide confinement factor Γwg and (b) modal loss αi of the fundamental and first-order hybrid gap modes versus nc at different h = 5, 10, and 15 nm and a fixed r = 70 nm. (c) and (d) are the counterparts of (a) and (b) at a fixed h = 10 nm and different r = 70, 100, and 130 nm. Symbols “F” and “1st” indicate fundamental and first-order modes, respectively.

The behaviors of Γwg and αi versus nc for different radii r and a fixed gap height h in Fig. 3(c) and (d) are analogous to those in Fig. 3(a) and (b). However, the effect of the wire radius r is less significant than that of the gap height h, as can be observed from quantitatively similar curves in Fig. 3(c) and (d).

A critical parameter as viewed from points of the lasing threshold is the necessary material gain which sustains the propagation of the mode without being attenuated. This gain is denoted as the transparency threshold gtr, which is one portion of the threshold gain gth in addition to the other component compensating the mirror loss of FP lasers. The transparency condition αi − Γwggtr = 0 directly gives rise to the expression of transparency threshold as gtr = αiwg. It is usually desired to minimize gtr under given constraints of guiding structures. In Fig. 4(a) and (b), we show the transparency threshold gains gtr of the fundamental and first-order modes corresponding to Fig. 3(a) and (b) as well as 3(c) and (d), respectively. Note that as mentioned earlier, the effect of group velocity vg,z on Γwg and αi is absent in gtr, and the information of the field distributions in the active region and metallic areas is clearer in gtr than in Γwg and αi.

Fig. 4 Transparency gains gtr of the fundamental and first-order hybrid gap modes at (a) different h = 5, 10, and 15 nm and a fixed r = 70 nm, and (b) different r = 70, 100, and 130 nm and a fixed h = 10 nm. Symbols “F” and “1st” indicate fundamental and first-order modes, respectively.

At nc = 3.5 (semiconductors), the transparency threshold of the first-order mode is usually lower than that of the fundamental one unless the gap height h is extremely narrow [for example, h = 5 nm in Fig. 4(a)]. At this stage, to minimize the propagation loss from the metal absorption in the presence of semiconductor claddings, the first-order transverse mode of this plasmonic waveguide should be the target mode. In the following calculations, we will therefore focus on threshold characteristics of the first-order mode.

3. Mirror reflectivity

The mirror loss is another factor hindering the lasing action of the plasmonic nanolaser. As the cavity length L of the FP cavity is shortened, the power leakage from two end facets is enhanced. In fact, with a cavity length L in the (sub)micron range, the mirror loss can easily dominate the propagation loss, and increasing the reflectivity becomes necessary for the threshold reduction. For this purpose, we consider Ag coatings of a few tens of nanometers at two end facets of the plasmonic cavity as reflectors.

Here, we adopt a simplified approach by sending an incident wave merely composed of the main guided mode at resonance onto the mirror and analyze the resulted reflected/total field. The reflected field contains many backward-propagating/evanescent components in addition to the one corresponding to the incident wave. We use the orthogonality theorem of waveguide modes [29

29. A. Yariv and P. Yeh, Optical Waves in Crystals (Wiley and Sons, Hoboken, NJ, 1997).

] to extract the backward-propagating amplitude corresponding to the main guided mode. The ratio between this backward-propagating amplitude and that of the incident wave is adopted as an estimation of the reflection coefficient. The effect from other nonresonant components is assumed minor, which is often valid when the resonance exhibits a decently narrow spectral linewidth.

The orthogonality theorem of modes in a waveguide consisting of isotropic materials reads as follows [29

29. A. Yariv and P. Yeh, Optical Waves in Crystals (Wiley and Sons, Hoboken, NJ, 1997).

]:
Adρ[El(ρ)×Hl(ρ)]z^=Adρ[E˜l(ρ)×Hl(ρ)]z^=δllΛl,
(2)
where El′(ρ) and Hl(ρ) are the cross-sectional electric and magnetic field profiles of modes l′ and l, respectively; l′ (ρ) is the backward-propagating/evanescent counterpart of El′ (ρ); δl′ l is the Kronecker delta; and Λl is a normalization constant. Note that conventionally, the form of l′(ρ) is chosen so that it has transverse (⊥ ) and longitudinal (|| ) components identical and opposite in signs to those of El′(ρ), respectively. We consider an incident wave entirely composed of the main resonant guided mode l of the FP cavity, namely,
Einc(r)=FlEl(ρ)eikz,lz,
(3)
where Fl and kz,l are the forward-propagating amplitude and propagation constant of mode l, respectively; and the origin of the coordinate z is set at the waveguide/mirror junction. In addition to Einc(r), the total field Etot(r) = Einc(r) + Er(r) at z < 0 also contains the reflected field Er(r), which can be expanded with backward-propagating/evanescent modes as
Er(r)=lBlE˜l(ρ)eikz,lz.
(4)
With the expression of Einc(r) in Eq. (3), 3D FEM, and a sufficient number of waveguide modes (five in this case) taken into account, the total field Etot(r) is numerically calculated.

Our goal is to extract the reflection coefficient of mode l defined as rm = Bl/Fl from the information of Etot(r) and the magnetic cross-sectional profile Hl(ρ). Using the orthogonality theorem in Eq. (2) and generalizing the approach in Ref. [28

28. S. W. Chang, T. R. Lin, and S. L. Chuang, “Theory of plasmonic Fabry-Perot nanolasers,” Opt. Express 18, 15039–15053 (2010) [CrossRef] [PubMed] .

], we integrate the quantity [Etot(r) × Hl(ρ)] · over the whole waveguide region A at z < 0 to eliminate amplitudes other than Fl and Bl and denote the outcome as a function f(z):
Adρ[Etot(r)×Hl(ρ)]z^f(z)=Λl(Fleikz,lz+Bleikz,lz)=C(eikz,lz+rmeikz,lz),
(5)
where C is the product ΛlFl. The magnitude |f(z)| at z < 0 exhibits an interference pattern of standing waves as follows:
|f(z)|=|C|e2Im[kz,l]z+|rm|2e2Im[kz,l]z+2|rm|cos(2Re[kz,l]zθr),
(6)
where θr is the phase angle of rm. The form of |f(z)| in Eq. (6) is utilized as a model function in the least squares fitting to the absolute value of the numerical integration at the left-hand side of Eq. (5). The magnitudes |C| and |rm| and phase angle θr are taken as three fitting parameters, and the value of |rm| which optimizes the fitting is used to estimate the reflectivity R = |rm|2 of the target FP mode.

In Fig. 5, we show the reflectivity of the first-order mode versus the thickness t of the Ag mirror at h = 10 nm, r = 70 nm, and nc = 3.5. From Fig. 5, without the Ag mirror (t = 0 nm), the reflection is completely due to the waveguide/air interface, and the corresponding reflectivity is 50.6 %. This reflectivity may bring about an enormous mirror loss and deteriorate the lasing performance if the cavity is short. On the other hand, Ag coatings of a few ten nanometers dramatically enhance the reflectivity. In the inset of Fig. 5, we show the standing-wave pattern |f(z)| and corresponding least-square fitting at t = 50 nm. The effective index of the guided mode defined as neff = kz/k0, where k0 is the vacuum propagation constant at the target wavelength of 1.55 μm, is 3.49 + 0.011i. The effective index neff (kz) determines the oscillation and decay/growth of the interference pattern. If the thickness t is more than 25 nm, the reflectivity R can be higher than 90 % (R = 90.4 % at t=25 nm). At t = 50 nm, the result indicates |rm| = 0.978 (R = 95.7 %) and θr = 1.180π. We note that the reflectivity calculated from simple Fresnel’s formula using the effective index neff and refractive index nm of Ag deviates significantly from the estimation here due to the invalid approximation of plane-wave incidences.

Fig. 5 The reflectivity R of the first-order mode as a function of the Ag thickness t at h = 10 nm, r = 70 nm, and nc = 3.5. Without the mirror, the reflectivity is about 50 %. As t > 25 nm, the reflectivity can exceed 90 %. The inset is the standing-wave pattern |f(z)| (circle marks) and its fitting (solid line) at t = 50 nm (R = 95.7 %).

4. Estimations from Fabry-Perot formulae and three-dimensional mode pattern

Table 1. The reflectivities, quality factors, and threshold gains of cavity modes corresponding to mirror thicknesses t = 0 (L = 660 and 1547 nm) and 50 nm (L = 625 and 1511 nm) at the wavelength of 1.55 μm. The cavity parameters are set as follows: h = 10 nm, r = 70 nm, and nc = 3.5.

table-icon
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To verify that QFP is a reasonable estimation of the Q factor for this plasmonic gap-mode nanocavity, we examine the mode at L = 1547 nm and t = 0 nm in Table 1 by carrying out 3D FEM calculations of the Q factor [28

28. S. W. Chang, T. R. Lin, and S. L. Chuang, “Theory of plasmonic Fabry-Perot nanolasers,” Opt. Express 18, 15039–15053 (2010) [CrossRef] [PubMed] .

, 31

31. COMSOL Multiphysics, http://www.comsol.com.

]. We excite the cavity mode by a ŷ-polarized plane wave which has a wavelength-independent strength and is normally incident onto one Ag mirror from the free space outside the cavity. The spatial integration of the square magnitude |E(r)|2 of the electric field inside the gap region (proportional to the stored electric energy) is recorded as the wavelength is varied through the resonance. The Q factor is then calculated from the ratio between the full width at half maximum (FWHM) and resonance wavelength of the corresponding lineshape. The outcome is illustrated in Fig. 6. From the FWHM linewidth Δλ ≈ 58.9 nm, the Q factor is around 26.43, which is in reasonable agreement with QFP = 31.2. We then look into the field profile of the high-Q mode at L = 1511 nm and t = 50 nm, which is potentially more promising for lasing than other modes. In Fig. 7, we illustrate the field profile excited by the ŷ-polarized plane wave at 1.55 μm. One can observe the subwavelength confinement of the plasmonic hybrid gap mode in the dielectric gap, as shown in Fig. 7(a). Due to the mode matching at the waveguide/mirror junction, the cross-sectional profile of the 3D mode pattern slightly deviates from that of the first-order mode in the infinitely long plasmonic waveguide. However, these two cross-sectional profile resemble each other, as can be observed from Figs. 2(d) and 7(b). In fact, detailed comparisons reveal that not only the overall profile but also each Cartesian component of the two fields are similar to each other. This phenomenon indicates that the first-order mode is almost perfect for the mode matching at the waveguide/mirror junction. Therefore, estimations of reflection coefficients using the single-mode standing-wave pattern |f(z)| in Eq. (6) should be quite accurate. Figure 7(c) shows the top (oblique) view of the mode profile below the nanowire. In addition to the clear standing-wave pattern along FP cavity (z direction), the mode is also laterally confined (x direction).

Fig. 6 The resonance lineshape calculated from 3D FEM for the mode at L = 1547 nm and t = 0 nm. The corresponding Q factor is about 26.43.
Fig. 7 (a) The side view (yz plane), (b) front view (xy plane), and (c) top (oblique) view (xz plane) of the mode profile corresponding to the case of L = 1511 nm in Table 1. The field pattern is excited by a plane wave normally incident onto the Ag mirror from the free space outside the nanocavity.

The threshold gains gth,FP estimated from the FP formula in Table 1 are essential parameters of the nanolaser. As an independent check of these values, we incorporate a virtual gain (artificial and negative imaginary part of the permittivity of SiO2) into the active region [38

38. C. Manolatou and F. Rana, “Subwavelength nanopatch cavities for semiconductor plasmon lasers,” IEEE J. Quantum Electron. 44, 435–447 (2008) [CrossRef] .

, 39

39. A. Mock, “First principles derivation of microcavity semiconductor laser threshold condition and its application to FDTD active cavity modeling,” J. Opt. Soc. Am. B 27, 2262–2272 (2010) [CrossRef] .

] and carry out a frequency scanning of the field energy in the FP cavity by varying the wavelength of the incident plane wave around the resonance of 1.55 μm [28

28. S. W. Chang, T. R. Lin, and S. L. Chuang, “Theory of plasmonic Fabry-Perot nanolasers,” Opt. Express 18, 15039–15053 (2010) [CrossRef] [PubMed] .

]. The obtained spectra would exhibit a very narrow lineshape (high warm-cavity Q factor) as the gain approaches the real threshold gain of the 3D cavity mode. The examinations indicate that the threshold gains obtained from the two approaches agree with each other.

From Table 1, the threshold gain gth,FP of the cavity at t = 50 nm and L = 625 nm (2041.4 cm−1) is still quite significant. Looking into the corresponding Q factor components Qabs and Qmir, we see that they are quite close. As Qabs due to the absorption (206.0) cannot be altered much once the cross section of the waveguide is fixed, we need to increase Qmir so that the threshold gain gth,FP can drop even lower. By increasing the cavity length L to 1511 nm, which also supports the resonance at 1.55 μm, the component Qmir (550.6) is enhanced and becomes larger than Qabs. The Q factor at this longer cavity length exceeds 100, and the corresponding threshold gain gth,FP (1472.5 cm−1) is lowered below 1500 cm−1. This threshold gain may be sustainable by, for example, colloidal QDs such as PbS with intense optical pumping [23

23. J. Grandidier, G. C. des Francs, S. Massenot, A. Bouhelier, L. Markey, J.-C. Weeber, C. Finot, and A. Dereux, “Gain-assisted propagation in a plasmonic waveguide at telecom wavelength,” Nano Lett. 9, 2935–2939 (2009) [CrossRef] [PubMed] .

, 24

24. D. Dai, Y. Shi, S. He, L. Wosinski, and L. Thylen, “Gain enhancement in a hybrid plasmonic nano-waveguide with a low-index or high-index gain medium,” Opt. Express 19, 12925–12936 (2011) [CrossRef] [PubMed] .

].

5. Conclusion

We have analyzed a plasmonic gap-mode nanocavity at telecommunication wavelengths near 1.55 μm in high-index claddings such as semiconductors. In the high-index condition, the first-order mode of the plasmonic guiding structure exhibits the better field confinement in the active region than the fundamental one does and is therefore more promising for lasing. The advantage of the first-order mode is also reflected on its lower transparency threshold gtr in this condition. We also study the dependence of the reflectivity on the thickness of the Ag reflector using the orthogonality theorem of waveguide modes and show that a decent reflectivity above 95 % is achievable with an Ag thickness of about a few tens of nanometers. This high reflectivity significantly lowers the mirror loss. For such cavities with a cavity length approaching 1.5 μm, a quality factor near 150 and threshold gain lower than 1500 cm−1 are achievable.

Acknowledgments

References and links

1.

J. A. Schuller, E. S. Barnard, W. Cai, Y. C. Jun, J. S. White, and M. L. Brongersma, “Plasmonics for extreme light concentration and manipulation,” Nature Mater. 9, 193–204 (2010) [CrossRef] .

2.

M. T. Hill, “Status and prospects for metallic and plasmonic nano-lasers [invited],” J. Opt. Soc. B 27, B36–B44 (2010) [CrossRef] .

3.

R. M. Ma, R. F. Oulton, V. J. Sorger, and X. Zhang, “Plasmon lasers: coherent light source at molecular scales,” Laser & Photon. Rev. 7, 1–21 (2013).

4.

M. Lončar, A. Scherer, and Y. Qiu, “Photonic crystal laser sources for chemical detection,” Appl. Phys. Lett. 82, 4648–4650 (2003) [CrossRef] .

5.

Y. Nakayama, P. J. Pauzauskie, A. Radenovic, R. M. Onorato, R. J. Saykally, J. Liphardt, and P. Yang, “Tunable nanowire nonlinear optical probe,” Nature 447, 1098–1101 (2007) [CrossRef] [PubMed] .

6.

R. G. Beausoleil, P. J. Kuekes, G. S. Snider, S. Y. Wang, and R. S. Williams, “Nanoelectronic and nanophotonic interconnect,” Proc. IEEE 96, 230–247 (2008) [CrossRef] .

7.

M. T. Hill, Y. S. Oei, B. Smalbrugge, Y. Zhu, T. de Vries, P. J. van Veldhoven, F. W. M. van Otten, T. J. Eijkemans, J. P. Turkiewicz, H. de Waardt, E. J. Geluk, S. H. Kwon, Y. H. Lee, R. Nötzel, and M. K. Smit, “Lasing in metallic-coated nanocavities,” Nat. Photonics 1, 589–594 (2007) [CrossRef] .

8.

M. T. Hill, M. Marell, E. S. P. Leong, B. Smalbrugge, Y. Zhu, M. Sun, P. J. van Veldhoven, E. J. Geluk, F. Karouta, Y. S. Oei, R. Nötzel, C. Z. Ning, and M. K. Smit, “Lasing in metal-insulator-metal sub-wavelength plasmonic waveguides,” Opt. Express 17, 11107–11112 (2009) [CrossRef] [PubMed] .

9.

M. A. Noginov, G. Zhu, A. M. Belgrave, R. Bakker, V. M. Shalaev, E. E. Narimanov, S. Stout, E. Herz, T. Suteewong, and U. Wiesner, “Demonstration of a spaser-based nanolaser,” Nature 460, 1110–1112 (2009) [CrossRef] [PubMed] .

10.

R. F. Oulton, V. J. Sorger, T. Zentgraf, R. M. Ma, C. Gladden, L. Dai, G. Bartal, and X. Zhang, “Plasmon lasers at deep subwavelength scale,” Nature 461, 629–632 (2009) [CrossRef] [PubMed] .

11.

C. Y. Lu, S. W. Chang, S. L. Chuang, T. D. Germann, and D. Bimberg, “Metal-cavity surface-emitting microlaser at room temperature,” Appl. Phys. Lett. 96, 251101 (2010) [CrossRef] .

12.

S. H. Kwon, J. H. Kang, C. Seassal, S. K. Kim, P. Regreny, Y. H. Lee, C. M. Lieber, and H. G. Park, “Subwavelength plasmonic lasing from a semiconductor nanodisk with silver nanopan cavity,” Nano Lett. 10, 3679–3683 (2010) [CrossRef] [PubMed] .

13.

R. M. Ma, R. F. Oulton, V. J. Sorger, G. Bartal, and X. Zhang, “Room-temperature sub-diffraction-limited plasmon laser by total internal reflection,” Nature Mater. 10, 110–113 (2011) [CrossRef] .

14.

R. A. Flynn, C. S. Kim, I. Vurgaftman, M. Kim, J. R. Meyer, A. J. Mak̈inen, K. Bussmann, L. Cheng, F. S. Choa, and J. P. Long, “A room-temperature semiconductor spaser operating near 1.5 μm,” Opt. Express 19, 8954–8961 (2011) [CrossRef] [PubMed] .

15.

M. J. H. Marell, B. Smalbrugge, E. J. Geluk, P. J. van Veldhoven, B. Barcones, B. Koopmans, R. Nötzel, M. K. Smit, and M. T. Hill, “Plasmonic distributed feedback lasers at telecommunications wavelengths,” Opt. Express 19, 15109–15118 (2011) [CrossRef] [PubMed] .

16.

A. M. Lakhani, M. K. Kim, E. K. Lau, and M. C. Wu, “Plasmonic crystal defect nanolaser,” Opt. Express 19, 18237–18245 (2011) [CrossRef] [PubMed] .

17.

C. Y. Wu, C. T. Kuo, C. Y. Wang, C. L. He, M. H. Lin, H. Ahn, and S. Gwo, “Plasmonic green nanolaser based on a metal-oxide-semiconductor structure,” Nano Lett. 11, 4256–4260 (2011) [CrossRef] [PubMed] .

18.

K. J. Russell, T. L. Liu, S. Cui, and E. L. Hu, “Large spontaneous emission enhancement in plasmonic nanocavities,” Nat. Photonics 6, 459–462 (2012) [CrossRef] .

19.

K. J. Russell and E. L. Hu, “Gap-mode plasmonic nanocavity,” Appl. Phys. Lett. 97, 163115 (2010) [CrossRef] .

20.

C. Y. Lu, S. W. Chang, S. L. Chuang, T. D. Germann, U. W. Pohl, and D. Bimberg, “Low thermal impedance of substrate-free metal cavity surface-emitting microlasers,” IEEE Photon. Technol. Lett. 23, 1031–1033 (2011) [CrossRef] .

21.

R. F. Oulton, V. J. Sorger, D. A. Genov, D. F. P. Pile, and X. Zhang, “A hybrid plasmonic waveguide for sub-wavelength confinement and long-range propagation,” Nat. Photonics 2, 496–500 (2008) [CrossRef] .

22.

P. J. Cheng, C. Y. Weng, S. W. Chang, T. R. Lin, and C. H. Tien, “Cladding effect on hybrid plasmonic nanowire cavity at telecommunication wavelengths,” IEEE J. Sel. Top. Quantum Electron. 19, 4800306 (2013) [CrossRef] .

23.

J. Grandidier, G. C. des Francs, S. Massenot, A. Bouhelier, L. Markey, J.-C. Weeber, C. Finot, and A. Dereux, “Gain-assisted propagation in a plasmonic waveguide at telecom wavelength,” Nano Lett. 9, 2935–2939 (2009) [CrossRef] [PubMed] .

24.

D. Dai, Y. Shi, S. He, L. Wosinski, and L. Thylen, “Gain enhancement in a hybrid plasmonic nano-waveguide with a low-index or high-index gain medium,” Opt. Express 19, 12925–12936 (2011) [CrossRef] [PubMed] .

25.

M. Ozeki, “Atomic layer epitaxy of III–V compounds using metalorganic and hydride sources,” Mater. Sci. Rep. 8, 97–146 (1992) [CrossRef] .

26.

S. M. George, “Atomic layer deposition: an overview,” Chem. Rev. 110, 111–131 (2010) [CrossRef] .

27.

D. P. Arnold, F. Cros, I. Zana, D. R. Veazie, and M. G. Allen, “Electroplated metal microstructures embedded in fusion-bonded silicon: conductors and magnetic materials,” J. Microelectromech. Syst. 13, 791–798 (2004) [CrossRef] .

28.

S. W. Chang, T. R. Lin, and S. L. Chuang, “Theory of plasmonic Fabry-Perot nanolasers,” Opt. Express 18, 15039–15053 (2010) [CrossRef] [PubMed] .

29.

A. Yariv and P. Yeh, Optical Waves in Crystals (Wiley and Sons, Hoboken, NJ, 1997).

30.

P. B. Johnson and R. W. Christy, “Optical constants of the noble metals,” Phys. Rev. B 6, 4370–4379 (1972) [CrossRef] .

31.

COMSOL Multiphysics, http://www.comsol.com.

32.

S. Zhang and H. Xu, “Optimizing substrate-mediated plasmon coupling toward high-performance plasmonic nanowire waveguides,” ACS Nano 6, 8128–8135 (2012) [CrossRef] [PubMed] .

33.

T. R. Lin, S. W. Chang, S. L. Chuang, Z. Zhang, and P. J. Schuck, “Coating effect on optical resonance of plasmonic nanobowtie antenna,” Appl. Phys. Lett. 97, 063106 (2010) [CrossRef] .

34.

T. D. Visser, H. Blok, B. Demeulenaere, and D. Lenstra, “Confinement factors and gain in optical amplifiers,” IEEE J. Quantum Electron. 33, 1763–1766 (1997) [CrossRef] .

35.

A. V. Maslov and C. Z. Ning, “Modal gain in a semiconductor nanowire laser with anisotropic bandstructure,” IEEE. J. Quantum Electron. 40, 1389–1397 (2004) [CrossRef] .

36.

S. W. Chang and S. L. Chuang, “Fundamental formulation for plasmonic nanolasers,” IEEE J. Quantum Electron. 45, 1014–1023 (2009) [CrossRef] .

37.

C. Y. Lu and S. L. Chuang, “A surface-emitting 3D metal-nanocavity laser: proposal and theory,” Opt. Express 19, 13225–13244 (2011) [CrossRef] [PubMed] .

38.

C. Manolatou and F. Rana, “Subwavelength nanopatch cavities for semiconductor plasmon lasers,” IEEE J. Quantum Electron. 44, 435–447 (2008) [CrossRef] .

39.

A. Mock, “First principles derivation of microcavity semiconductor laser threshold condition and its application to FDTD active cavity modeling,” J. Opt. Soc. Am. B 27, 2262–2272 (2010) [CrossRef] .

OCIS Codes
(140.3410) Lasers and laser optics : Laser resonators
(230.7370) Optical devices : Waveguides
(240.6680) Optics at surfaces : Surface plasmons
(260.3910) Physical optics : Metal optics
(250.5960) Optoelectronics : Semiconductor lasers

ToC Category:
Lasers and Laser Optics

History
Original Manuscript: February 22, 2013
Revised Manuscript: May 6, 2013
Manuscript Accepted: May 21, 2013
Published: May 29, 2013

Citation
Pi-Ju Cheng, Chen-Ya Weng, Shu-Wei Chang, Tzy-Rong Lin, and Chung-Hao Tien, "Plasmonic gap-mode nanocavities with metallic mirrors in high-index cladding," Opt. Express 21, 13479-13491 (2013)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-11-13479


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References

  1. J. A.  Schuller, E. S.  Barnard, W.  Cai, Y. C.  Jun, J. S.  White, M. L.  Brongersma, “Plasmonics for extreme light concentration and manipulation,” Nature Mater. 9, 193–204 (2010). [CrossRef]
  2. M. T.  Hill, “Status and prospects for metallic and plasmonic nano-lasers [invited],” J. Opt. Soc. B 27, B36–B44 (2010). [CrossRef]
  3. R. M.  Ma, R. F.  Oulton, V. J.  Sorger, X.  Zhang, “Plasmon lasers: coherent light source at molecular scales,” Laser & Photon. Rev. 7, 1–21 (2013).
  4. M.  Lončar, A.  Scherer, Y.  Qiu, “Photonic crystal laser sources for chemical detection,” Appl. Phys. Lett. 82, 4648–4650 (2003). [CrossRef]
  5. Y.  Nakayama, P. J.  Pauzauskie, A.  Radenovic, R. M.  Onorato, R. J.  Saykally, J.  Liphardt, P.  Yang, “Tunable nanowire nonlinear optical probe,” Nature 447, 1098–1101 (2007). [CrossRef] [PubMed]
  6. R. G.  Beausoleil, P. J.  Kuekes, G. S.  Snider, S. Y.  Wang, R. S.  Williams, “Nanoelectronic and nanophotonic interconnect,” Proc. IEEE 96, 230–247 (2008). [CrossRef]
  7. M. T.  Hill, Y. S.  Oei, B.  Smalbrugge, Y.  Zhu, T.  de Vries, P. J.  van Veldhoven, F. W. M.  van Otten, T. J.  Eijkemans, J. P.  Turkiewicz, H.  de Waardt, E. J.  Geluk, S. H.  Kwon, Y. H.  Lee, R.  Nötzel, M. K.  Smit, “Lasing in metallic-coated nanocavities,” Nat. Photonics 1, 589–594 (2007). [CrossRef]
  8. M. T.  Hill, M.  Marell, E. S. P.  Leong, B.  Smalbrugge, Y.  Zhu, M.  Sun, P. J.  van Veldhoven, E. J.  Geluk, F.  Karouta, Y. S.  Oei, R.  Nötzel, C. Z.  Ning, M. K.  Smit, “Lasing in metal-insulator-metal sub-wavelength plasmonic waveguides,” Opt. Express 17, 11107–11112 (2009). [CrossRef] [PubMed]
  9. M. A.  Noginov, G.  Zhu, A. M.  Belgrave, R.  Bakker, V. M.  Shalaev, E. E.  Narimanov, S.  Stout, E.  Herz, T.  Suteewong, U.  Wiesner, “Demonstration of a spaser-based nanolaser,” Nature 460, 1110–1112 (2009). [CrossRef] [PubMed]
  10. R. F.  Oulton, V. J.  Sorger, T.  Zentgraf, R. M.  Ma, C.  Gladden, L.  Dai, G.  Bartal, X.  Zhang, “Plasmon lasers at deep subwavelength scale,” Nature 461, 629–632 (2009). [CrossRef] [PubMed]
  11. C. Y.  Lu, S. W.  Chang, S. L.  Chuang, T. D.  Germann, D.  Bimberg, “Metal-cavity surface-emitting microlaser at room temperature,” Appl. Phys. Lett. 96, 251101 (2010). [CrossRef]
  12. S. H.  Kwon, J. H.  Kang, C.  Seassal, S. K.  Kim, P.  Regreny, Y. H.  Lee, C. M.  Lieber, H. G.  Park, “Subwavelength plasmonic lasing from a semiconductor nanodisk with silver nanopan cavity,” Nano Lett. 10, 3679–3683 (2010). [CrossRef] [PubMed]
  13. R. M.  Ma, R. F.  Oulton, V. J.  Sorger, G.  Bartal, X.  Zhang, “Room-temperature sub-diffraction-limited plasmon laser by total internal reflection,” Nature Mater. 10, 110–113 (2011). [CrossRef]
  14. R. A.  Flynn, C. S.  Kim, I.  Vurgaftman, M.  Kim, J. R.  Meyer, A. J.  Mak̈inen, K.  Bussmann, L.  Cheng, F. S.  Choa, J. P.  Long, “A room-temperature semiconductor spaser operating near 1.5 μm,” Opt. Express 19, 8954–8961 (2011). [CrossRef] [PubMed]
  15. M. J. H.  Marell, B.  Smalbrugge, E. J.  Geluk, P. J.  van Veldhoven, B.  Barcones, B.  Koopmans, R.  Nötzel, M. K.  Smit, M. T.  Hill, “Plasmonic distributed feedback lasers at telecommunications wavelengths,” Opt. Express 19, 15109–15118 (2011). [CrossRef] [PubMed]
  16. A. M.  Lakhani, M. K.  Kim, E. K.  Lau, M. C.  Wu, “Plasmonic crystal defect nanolaser,” Opt. Express 19, 18237–18245 (2011). [CrossRef] [PubMed]
  17. C. Y.  Wu, C. T.  Kuo, C. Y.  Wang, C. L.  He, M. H.  Lin, H.  Ahn, S.  Gwo, “Plasmonic green nanolaser based on a metal-oxide-semiconductor structure,” Nano Lett. 11, 4256–4260 (2011). [CrossRef] [PubMed]
  18. K. J.  Russell, T. L.  Liu, S.  Cui, E. L.  Hu, “Large spontaneous emission enhancement in plasmonic nanocavities,” Nat. Photonics 6, 459–462 (2012). [CrossRef]
  19. K. J.  Russell E. L.  Hu, “Gap-mode plasmonic nanocavity,” Appl. Phys. Lett. 97, 163115 (2010). [CrossRef]
  20. C. Y.  Lu, S. W.  Chang, S. L.  Chuang, T. D.  Germann, U. W.  Pohl, D.  Bimberg, “Low thermal impedance of substrate-free metal cavity surface-emitting microlasers,” IEEE Photon. Technol. Lett. 23, 1031–1033 (2011). [CrossRef]
  21. R. F.  Oulton, V. J.  Sorger, D. A.  Genov, D. F. P.  Pile, X.  Zhang, “A hybrid plasmonic waveguide for sub-wavelength confinement and long-range propagation,” Nat. Photonics 2, 496–500 (2008). [CrossRef]
  22. P. J.  Cheng, C. Y.  Weng, S. W.  Chang, T. R.  Lin, C. H.  Tien, “Cladding effect on hybrid plasmonic nanowire cavity at telecommunication wavelengths,” IEEE J. Sel. Top. Quantum Electron. 19, 4800306 (2013). [CrossRef]
  23. J.  Grandidier, G. C.  des Francs, S.  Massenot, A.  Bouhelier, L.  Markey, J.-C.  Weeber, C.  Finot, A.  Dereux, “Gain-assisted propagation in a plasmonic waveguide at telecom wavelength,” Nano Lett. 9, 2935–2939 (2009). [CrossRef] [PubMed]
  24. D.  Dai, Y.  Shi, S.  He, L.  Wosinski, L.  Thylen, “Gain enhancement in a hybrid plasmonic nano-waveguide with a low-index or high-index gain medium,” Opt. Express 19, 12925–12936 (2011). [CrossRef] [PubMed]
  25. M.  Ozeki, “Atomic layer epitaxy of III–V compounds using metalorganic and hydride sources,” Mater. Sci. Rep. 8, 97–146 (1992). [CrossRef]
  26. S. M.  George, “Atomic layer deposition: an overview,” Chem. Rev. 110, 111–131 (2010). [CrossRef]
  27. D. P.  Arnold, F.  Cros, I.  Zana, D. R.  Veazie, M. G.  Allen, “Electroplated metal microstructures embedded in fusion-bonded silicon: conductors and magnetic materials,” J. Microelectromech. Syst. 13, 791–798 (2004). [CrossRef]
  28. S. W.  Chang, T. R.  Lin, S. L.  Chuang, “Theory of plasmonic Fabry-Perot nanolasers,” Opt. Express 18, 15039–15053 (2010). [CrossRef] [PubMed]
  29. A.  Yariv P.  Yeh, Optical Waves in Crystals (Wiley and Sons, Hoboken, NJ, 1997).
  30. P. B.  Johnson R. W.  Christy, “Optical constants of the noble metals,” Phys. Rev. B 6, 4370–4379 (1972). [CrossRef]
  31. COMSOL Multiphysics, http://www.comsol.com .
  32. S.  Zhang H.  Xu, “Optimizing substrate-mediated plasmon coupling toward high-performance plasmonic nanowire waveguides,” ACS Nano 6, 8128–8135 (2012). [CrossRef] [PubMed]
  33. T. R.  Lin, S. W.  Chang, S. L.  Chuang, Z.  Zhang, P. J.  Schuck, “Coating effect on optical resonance of plasmonic nanobowtie antenna,” Appl. Phys. Lett. 97, 063106 (2010). [CrossRef]
  34. T. D.  Visser, H.  Blok, B.  Demeulenaere, D.  Lenstra, “Confinement factors and gain in optical amplifiers,” IEEE J. Quantum Electron. 33, 1763–1766 (1997). [CrossRef]
  35. A. V.  Maslov C. Z.  Ning, “Modal gain in a semiconductor nanowire laser with anisotropic bandstructure,” IEEE. J. Quantum Electron. 40, 1389–1397 (2004). [CrossRef]
  36. S. W.  Chang S. L.  Chuang, “Fundamental formulation for plasmonic nanolasers,” IEEE J. Quantum Electron. 45, 1014–1023 (2009). [CrossRef]
  37. C. Y.  Lu S. L.  Chuang, “A surface-emitting 3D metal-nanocavity laser: proposal and theory,” Opt. Express 19, 13225–13244 (2011). [CrossRef] [PubMed]
  38. C.  Manolatou F.  Rana, “Subwavelength nanopatch cavities for semiconductor plasmon lasers,” IEEE J. Quantum Electron. 44, 435–447 (2008). [CrossRef]
  39. A.  Mock, “First principles derivation of microcavity semiconductor laser threshold condition and its application to FDTD active cavity modeling,” J. Opt. Soc. Am. B 27, 2262–2272 (2010). [CrossRef]

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