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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 23 — Nov. 18, 2013
  • pp: 28570–28582
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Dual-wavelength orthogonally polarized radiation generated by a tungsten thermal source

Fang Han, Xiangli Sun, Lijun Wu, and Qiang Li  »View Author Affiliations


Optics Express, Vol. 21, Issue 23, pp. 28570-28582 (2013)
http://dx.doi.org/10.1364/OE.21.028570


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Abstract

Developing controllable radiation sources in the mid-infrared spectral region is significant in photonics technology because of rare available resources. Based on the thermal emission from a one-dimensional shallow tungsten grating, we propose a two-dimensional orthogonally-crossed shallow grating to produce an orthogonally-polarized dual-wavelength radiation with the emissivity as high as 78% and 91% from a single surface. The simulation shows that the field is intensively concentrated in vicinity of the air-tungsten interface when surface plasmon polaritons are excited. In addition, by optimizing the geometric parameters of the grating, the field is found to be more concentrated which leads to higher emissivity. The two wavelengths can be produced independently or simultaneously, depending on the polarization of the picking-up polarizer. Our investigations can help us developing controllable multi-wavelength thermal radiation sources from a single surface.

© 2013 Optical Society of America

1. Introduction

Spatially and spectrally controllable light sources are key components in the application of photonics technology. In the mid-infrared spectral region, utilizing light emitting diodes or quantum cascade lasers as radiating sources is limited because of their high cost and low energy, it is thus very important to find cost-effective and efficient alternatives [1

1. J.-J. Greffet, “Applied physics: Controlled incandescence,” Nature 478(7368), 191–192 (2011). [CrossRef] [PubMed]

].

In nondispersive infrared analysis, the concentration of a specific chemical compound in liquids or gases is determined by comparing the absorption difference at two wavelengths (one as the characteristic wavelength and the other as the reference) [15

15. H. T. Miyazaki, K. Ikeda, T. Kasaya, K. Yamamoto, Y. Inoue, K. Fujimura, T. Kanakugi, M. Okada, K. Hatade, and S. Kitagawa, “Thermal emission of two-color polarized infrared waves from integrated plasmon cavities,” Appl. Phys. Lett. 92(14), 141114 (2008). [CrossRef]

, 16

16. K. Masuno, T. Sawada, S. Kumagai, and M. Sasaki, “Multiwavelength Selective IR Emission Using Surface Plasmon Polaritons for Gas Sensing,” IEEE Photon. Technol. Lett. 23(22), 1661–1663 (2011). [CrossRef]

]. It is thus very important to obtain arbitrarily selectable dual-wavelength emission in the mid-infrared spectral region. Nonetheless, only a few articles have focused on designing applicable architecture for this purpose [16

16. K. Masuno, T. Sawada, S. Kumagai, and M. Sasaki, “Multiwavelength Selective IR Emission Using Surface Plasmon Polaritons for Gas Sensing,” IEEE Photon. Technol. Lett. 23(22), 1661–1663 (2011). [CrossRef]

].

When the depth of the grating is comparable to λ/2, the resonance will be induced by microcavity effects, in which the emission wavelength is determined by the resonance of the cavity [2

2. C. Arnold, F. Marquier, M. Garin, F. Pardo, S. Collin, N. Bardou, J.-L. Pelouard, and J.-J. Greffet, “Coherent thermal infrared emission by two-dimensional silicon carbide gratings,” Phys. Rev. B 86(3), 035316 (2012). [CrossRef]

4

4. P. J. Hesketh, J. N. Zemel, and B. Gebhart, “Organ pipe radiant modes of periodic micromachined silicon surfaces,” Nature 324(6097), 549–551 (1986). [CrossRef]

]. It is impossible to obtain more than one resonant wavelength by simply arranging one type of microcavities [13

13. N. Nguyen-Huu, Y. B. Chen, and Y. L. Lo, “Development of a polarization-insensitive thermophotovoltaic emitter with a binary grating,” Opt. Express 20(6), 5882–5890 (2012). [CrossRef] [PubMed]

]. On the other hand, the thermal emission is highly polarized for 1D microcavity arrays [4

4. P. J. Hesketh, J. N. Zemel, and B. Gebhart, “Organ pipe radiant modes of periodic micromachined silicon surfaces,” Nature 324(6097), 549–551 (1986). [CrossRef]

], while that for 2D ones is randomly polarized [3

3. S. Maruyama, T. Kashiwa, H. Yugami, and M. Esashi, “Thermal radiation from two-dimensionally confined modes in microcavities,” Appl. Phys. Lett. 79(9), 1393 (2001). [CrossRef]

]. By arranging two types of 1D microcavities, in which vertical and horizontal resonances are combined, into a checkboard-like structure, Miyazaki et al [14

14. Y.-B. Chen and Z. M. Zhang, “Design of tungsten complex gratings for thermophotovoltaic radiators,” Opt. Commun. 269(2), 411–417 (2007). [CrossRef]

] has observed orthogonally polarized two-wavelength infrared waves thermally emitted from deep Au gratings. It is a simple and useful design. However, only half of the light source (50%) is valid for one polarization in order to obtain orthogonally polarized dual-wavelength emission from the microcavities in their design.

If the depth of the grating is shallow (much smaller than λ/2), the resonance can be induced by the excitation of SPPs [12

12. M. Laroche, C. Arnold, F. Marquier, R. Carminati, J.-J. Greffet, S. Collin, N. Bardou, and J.-L. Pelouard, “Highly directional radiation generated by a tungsten thermal source,” Opt. Lett. 30(19), 2623–2625 (2005). [CrossRef] [PubMed]

14

14. Y.-B. Chen and Z. M. Zhang, “Design of tungsten complex gratings for thermophotovoltaic radiators,” Opt. Commun. 269(2), 411–417 (2007). [CrossRef]

]. As the microcavity effect cannot be formed in this case, it is possible to control the polarization at different wavelength independently if we combine different shallow gratings (azimuthally arranged) to compensate the extra moments required for excitation of SPPs at different directions.

In the present work, we propose a 2D orthogonally-crossed shallow grating to produce dual-wavelength emission with orthogonally polarizations from a single surface. Tungsten is chosen as the materials because it can sustain high temperature (more than 2000K) with good corrosion resistance and can support SPPs in the infrared wavelength range [12

12. M. Laroche, C. Arnold, F. Marquier, R. Carminati, J.-J. Greffet, S. Collin, N. Bardou, and J.-L. Pelouard, “Highly directional radiation generated by a tungsten thermal source,” Opt. Lett. 30(19), 2623–2625 (2005). [CrossRef] [PubMed]

]. It had been widely used as thermal source. Both the grating and its supporting substrate are made of tungsten for easy fabrication.

We mainly focus on the wave numbers between 2500 cm−1 and 4000 cm−1 (corresponding to the wavelength range 4-2.5 μm) as they are in the stretching vibration frequency range of O-H, N-H and C-H. However, the principal can be easily extended to other frequency range.

The simulation in the present paper is based on the rigorous coupled-wave analysis (RCWA) method (from Rsoft Design Group) and the COMSOL Multiphysics finite element analysis (FEA) software. RCWA is used to compute emittance spectra and FEA the corresponding electromagnetic (EM) field distributions in vicinity of the tungsten-air interface. We apply 2D/3D simulations for 1D/2D gratings respectively. A Perfectly Matched Layer (PML) boundary condition is applied for the top/bottom area and Periodic Boundary Condition (PBC) for the four walls. As the wavelength we are discussing in this paper is in the range of 2.5-4 μm, the grid size 10 nm which corresponds to ~λ/250 ensures the convergence of the results both for 2D and 3D simulations. The frequency-dependent complex relative dielectric constant of the tungsten used in our simulations is characterized by a Lorentz-Drude model [17

17. A. D. Rakic, A. B. Djurisic, J. M. Elazar, and M. L. Majewski, “Optical properties of metallic films for vertical-cavity optoelectronic devices,” Appl. Opt. 37(22), 5271–5283 (1998). [CrossRef] [PubMed]

]
εw(ω)=(1Ωp2ω(ωiΓ0))+I=1kfIωP2(ωI2ω2)+iωΓI,
(1)
where ωp is the plasma frequency. k is the number of oscillators with frequency ωI, strength fI and lifetime 1/ΓI. Ωp=f0ωp is the plasma frequency associated with intra-band transitions, in which f0 is the strength of the oscillator and Γ0 the damping constant. The values of all these parameters were taken from the reference [18

18. J. H. Weaver, C. G. Olson, and D. W. Lynch, “Optical properties of crystalline tungsten,” Phys. Rev. B 12(4), 1293–1297 (1975). [CrossRef]

].

2. Simulations for 1D grating

SPP is a coupled, localized EM wave that propagates along the interface between two different media due to charge density oscillation [20

20. W. L. Barnes, A. Dereux, and T. W. Ebbesen, “Surface plasmon subwavelength optics,” Nature 424(6950), 824–830 (2003). [CrossRef] [PubMed]

,21

21. Z. J. Zhong, Y. Xu, S. Lan, Q.-F. Dai, and L. J. Wu, “Sharp and asymmetric transmission response in metal-dielectric-metal plasmonic waveguides containing Kerr nonlinear media,” Opt. Express 18(1), 79–86 (2010). [CrossRef] [PubMed]

]. At the resonant wavelength, the EM field can be greatly enhanced near the interface, yielding a strong absorption and a sharp reduction in the reflectance within a narrow spectral band [10

10. J. G. Fleming, S. Y. Lin, I. El-Kady, R. Biswas, and K. M. Ho, “All-metallic three-dimensional photonic crystals with a large infrared bandgap,” Nature 417(6884), 52–55 (2002). [CrossRef] [PubMed]

]. In other words, the emissivity increase steeply since it equals to the absorbance according to Kirchhoff’s law. As the momentum of the SPP mode is greater than that of a free-space photon, the excitation of SPPs requires an electric-field component perpendicular to the grating to provide the extra moment [20

20. W. L. Barnes, A. Dereux, and T. W. Ebbesen, “Surface plasmon subwavelength optics,” Nature 424(6950), 824–830 (2003). [CrossRef] [PubMed]

]. Generally, such an electric field component exists in both transverse electric (TE) waves and transverse magnetic (TM) waves when the incident plane is not perpendicular to the grooves [22

22. M. Kretschmann, T. A. Leskova, and A. A. Maradudin, “Conical Propagation of a Surface Polariton Across a Grating,” Opt. Commun. 215(4-6), 205–223 (2003). [CrossRef]

]. Here, without loss of generality, we consider the situation with the incident plane being perpendicular to the groove. In this case, only the TM wave can excite SPPs to enhance the emissivity.

For a flat air-material interface, the surface plasmon wavevector propagating along the x direction, ksp,x, is determined by the dielectric constant of the metal (εm) and the wavevector in vacuum (k0) [23

23. H. Raether, Surface Plasmons (Springer, Berlin, 1988).

]:

ksp,x=k0εm(ω)1+εm(ω).
(2)

SPPs can be excited between the metal and air if a 1D grating is modulated in the x direction. The wavevector of SPP is then given by [13

13. N. Nguyen-Huu, Y. B. Chen, and Y. L. Lo, “Development of a polarization-insensitive thermophotovoltaic emitter with a binary grating,” Opt. Express 20(6), 5882–5890 (2012). [CrossRef] [PubMed]

]:
ksp,x=kox±jKx=k0sinθcosϕ+¯j2πΛ,
(3)
where Kx denotes the grating vector perpendicular to the grating grooves. Integer j represent the diffraction order while “+” and “-” signs correspond to j>0 and j <0 respectively. θ is the resonant angle of the incidence and ϕ is the azimuthal angle, as defined in Fig. 1(a). When the light incident vertically onto the grating, θ = 0°. Without loss of generality, we fix θ = 0° in the whole paper. The dielectric constant of tungsten, |εw|>>ε0 = 1 when λ > 2 μm [24

24. E. Rephaeli and S. Fan, “Tungsten black absorber for solar light with wide angular operation range,” Appl. Phys. Lett. 92(21), 211107 (2008). [CrossRef]

]. When θ = 0°, the resonant wavelength of SPP, λres, is given by,

λres=±Λjεw(ω)1+εw(ω).
(4)

Figure 1(b) illustrates the spectral emissivity of two independent 1D shallow gratings with Λ = 3.2 μm and 4 μm respectively. The higher emittance at short wavelength (λ <1.6 μm) is due to the intrinsic absorption of tungsten [24

24. E. Rephaeli and S. Fan, “Tungsten black absorber for solar light with wide angular operation range,” Appl. Phys. Lett. 92(21), 211107 (2008). [CrossRef]

]. Very sharp emittance peaks can be obviously seen at λ = 3.29/4.10 μm for Λ = 3.2/4 μm. The E-field distribution at different wavelengths are shown in Fig. 1(c) for Λ = 4 μm. At the wavelength of λ3 = 4.10 μm, the field is observed to be strongly localized near to the grating showing surface wave characteristic, revealing that the incident light is coupled to surface waves. At other wavelengths (λ1, λ2, λ4), the E-field is much weaker. Therefore, the strong emittance at the wavelength of 4.1 μm is due to the excitation of SPPs and their coupling to free space photons at the metal-air interface [25

25. B. J. Lee, Y.-B. Chen, and Z. M. Zhang, “Confinement of infrared radiation to nanometer scales through metallic slit arrays,” J. Quant. Spectrosc. Radiat. Transf. 109(4), 608–619 (2008). [CrossRef]

]. The peaks in the relatively short wavelength range (λ <2.5 μm) correspond to higher orders of SPPs as marked in the Fig. 1(b). As their emittance is obviously lower than that from the first order (j = 1), we will mainly concentrate on discussing the emission at j = 1 in the following of the paper.

λres=±Λjεweff(ω)1+εweff(ω).
(5)

With an increase of f, λres can be inferred to be red-shifted, which is consistent with the simulation results shown in Fig. 2 and Table 1. It is worth to note that the resonant wavelength blue shifts when the filling factor is very large. It may be due to a smaller influence from air since tungsten materials occupy most of the space in that case.

On the other hand, there are some differences between the effects of geometric parameters on the emittance for two different periods. For instance, in the case of 3.2 μm, the emittance approaches 1 for a large range of f (0.35-0.6) when h = 0.1 μm, suggesting that it is not significantly sensitive to f in this range. This characteristic provides a large fabrication tolerance for devices. In the case of 4 μm, the highest emittance is produced at h = 0.2 μm with f = 0.75-0.8. This is thought to be ascribed to the complicated effective filling factor which includes the effect from h and f as also analyzed in reference [14

14. Y.-B. Chen and Z. M. Zhang, “Design of tungsten complex gratings for thermophotovoltaic radiators,” Opt. Commun. 269(2), 411–417 (2007). [CrossRef]

].

As the field distribution can help us to understand the underlying physics of the influence from the filling factor, we chose Λ = 4 μm as an example to analyze the trend. In Fig. 2(e), we can see two climaxes in the emittance spectrum which corresponds to f = 0.4 and 0.85 respectively. The corresponding E-field distributions at resonant are displayed in Fig. 3(a) in which a strong confinement of the field can be observed due to the excitation of SPPs. The specific E-field distribution for f = 0.85 and f = 0.4 is however different. We plot the field intensity along the magenta dotted straight line away from the air-tungsten interface in Fig. 3(b). As shown, the field intensity drops to 1/e at a distance of 3.8 μm/9.9 μm for f = 0.85/f = 0.4. The faster decaying away from the interface for f = 0.85 reveals that the field is more concentrated in vicinity of the air-tungsten interface, which results in a higher emittance since more photons can be absorbed.
Fig. 3 (a) E-field distributions at resonant wavelength for f = 0.85 and 0.4 respectively. (b) Corresponding E-field intensity (normalized to the highest value) versus the distance away from the air-tungsten interface for f = 0.85 and 0.4 along with the vertical magenta dotted line in the field distribution map as shown (a). The stars plot the calculated values and lines the fitting exponential functions. Obviously, the field decays to 1/e at a distance of 3.8 for f = 0.85 while 9.9 μm for f = 0.4, revealing that the field is more intensively concentrated in vicinity of the interface and more photons can be absorbed when f = 0.85.

From Eq. (3), the azimuthal angle ϕ would influence the wavelength of SPP when θ ≠ 0°. As we only consider θ = 0° in this paper, the effect of the azimuthal angle on the resonant wavelength is eliminated. Under this condition, different ϕ only means different incident polarization. As shown in Fig. 4, the resonant wavelength remains unchanged but the emissivity decreases from 1 to 0 with an increase of the angle ϕ, which can be attributed to the weakened coupling between the incident electric field and the grating.
Fig. 4 Emittance spectra at various azimuthal angles between the incident plane and x direction.

3. Simulations for orthogonally-crossed 2D grating

Fig. 5 (a) Schematic of the simulated orthogonally-crossed 2D tungsten grating. The geometry of the grating is determined by its periods (Λx and Λy). The definition of other geometric parameters is the same as in Fig. 1(a). Λx = Λy = 3.2 μm in (b)-(d). Emittance spectra of the 2D grating for TM waves at normal directions are shown in (b) for fx = fy = 0.3, h = 0.3 μm and (c) fx = fy = 0.3 with different h. Higher order mode (1,1) and (2,0) can be observed in (b) as expected. (d) Emittance spectra with fx = fy being varied from 0.1 to 0.6 when h = 0.3 μm. The dotted lines display the full width at half maximum (FWHM), which increases with the filling ratio.
From the results in Section 2, the emission wavelength is mainly determined by the period of the grating via the excitation of SPPs in a 1D shallow grating. It is straightforward to try if the thermal emission containing two independent resonant wavelengths with perpendicular polarizations can be produced by an orthogonally-crossed grating from a single surface. Figure 5(a) displays the schematic of an orthogonally-crossed grating with fx = dx/Λx and fy = dy/Λy defining the filling ratio for x and y directions respectively. By extending Eq. (5), the resonant wavelengths along the x and y directions for an orthogonally-crossed grating are given by,
λres,x=ΛxΛy(jxΛy)2+(jyΛx)2εweff,x(ω)1+εweff,x(ω)λres,y=ΛxΛy(jxΛy)2+(jyΛx)2εweff,y(ω)1+εweff,y(ω).}
(6)
Integer jx/iy represents the diffraction order and εweff,x/εweff,y the effective dielectric constant along x/y direction respectively. Obviously, in an orthogonally-crossed 2D grating, the emission wavelength is also mainly determined by the period of the grating. However, its emittance spectrum would show a more complicated behavior because more vectorial combination between the grating vectors exists to fulfill the condition for the excitation of SPPs [26

26. D. L. C. Chan, M. Soljacić, and J. D. Joannopoulos, “Thermal emission and design in 2D-periodic metallic photonic crystal slabs,” Opt. Express 14(19), 8785–8796 (2006). [CrossRef] [PubMed]

]. We started the simulation by setting Λx = Λy = 3.2 μm, as illustrated in Fig. 5(b). Comparing to the results in Fig. 1(b), we can see an additional plasmon excitation at the diffraction order of (jx, iy) = (1,1), as we expect.

From the discussions in Section 2, it is known that the coupling efficiency between the incident light and SPPs shows strong dependence on the filling ratio and depth of the grating. We investigate the effect of the grating depth at first. For easy fabrication, h is defined to be the same for x and y directions. As the 3D simulation is time-consuming, we scanned only the wavelength range we are interested, i.e. around the resonant peak corresponding to (jx, iy) = (1,0) and (0,1). From Fig. 5(c) we can observe that an emittance as high as 1 can be produced when h = 0.3 μm.

The filling factor from orthogonal directions would influence each other. The effective filling factor for the orthogonally-crossed grating can be defined as feff = fx + fy - fxfy. According to the results from 1D grating as shown in Fig. 2, we scanned the filling factor from fx = fy = 0.1 to 0.6 to obtain the highest emissivity. As illustrated in Fig. 5(d), the emissivity can reach 1 both for x and y directions when fx = fy is in the range of 0.3-0.5. With an increase of the filling ratio, the width of the emissivity is increased, which leads to a decrease of the spectral coherence of the emission [27

27. S. E. Han and D. J. Norris, “Beaming thermal emission from hot metallic bull’s eyes,” Opt. Express 18(5), 4829–4837 (2010). [CrossRef] [PubMed]

]. Therefore, a smaller filling ratio is preferable when the emissivity is similar.

Comparing the results for 1D and 2D gratings, we can find that the influence trend of the filling factor on the emission is consistent. For example, when fx = fy is in the range of 0.3-0.5, feff is in the range of 0.51-0.75, which corresponds to an ascending stage for the emittance in Fig. 2(d).

Then we set Λx = 3.2 μm and Λy = 4μm in order to control the resonant wavelength independently for x and y directions. Based on the results in Figs. 5(b)-5(d), we firstly set fx = fy and scan them simultaneously. A broad wavelength range (0.5-4.5 μm) has been scanned at first to understand the spectral position of the higher order modes. As expected, (1,1) mode appears both in x and y directions which corresponds to ϕ = 0° and 90° respectively, as shown in Fig. 6(a).
Fig. 6 (a) Emittance spectra of the orthogonally-crossed 2D grating for Λx = 3.2 and Λy = 4 μm with fx = fy = 0.3, h = 0.3 μm. Insets display E-field distributions at resonant for modes (1, 0) and (0, 1). (b)-(d) Emittance spectra at different f. Please note that in order to save simulating time, we only calculated the emittance near to the resonant wavelength corresponding to (1, 0) and (0, 1) modes respectively. (b) shows the emittance spectra of the 2D grating with different filling factors. fx and fy is varied simultaneously. (c) shows those with different fy when fx = 0.3 and (d) shows those with different fx when fy = 0.3. The results in the left panel are for x-direction (ϕ = 0°) and right panel for y-direction (ϕ = 90°).
There is a broad peak in the y-direction locating at ~3.48 μm (marked by a red solid circle) we cannot identify at the moment. As it is quite low and not so close to 4 μm, we can eliminate it by adding a long pass filter in the optical path in the applications. We then investigate the influence of the filling factor on the emittance around the resonant peak corresponding to (jx, iy) = (1,0) and (0,1). The results are shown in Fig. 6(b)-6(d). As can be seen, the emissivity from both x and y directions is relatively high when fx = fy = 0.3. We thus fix fx = 0.3 and scan fy. The results in Fig. 6(c) show that, the emissivity from the x direction increases with a decrease of fy while that from the y direction decreases. As the purpose here is to obtain independent dual-wavelength thermal emission, fy = 0.3 seems the best choice. At the same time, we fix fy = 0.3 and scan fx. Similar results are obtained as demonstrated in Fig. 6(d), in which the best emittance (with highest intensity and relative narrow width of the resonant peak for both wavelengths) is achieved for fx = fy = 0.3. This result is similar to that when Λx = Λy = 3.2 μm. It may be because that the period 4 and 3.2 μm is close to each other.

Provided only one emitting wavelength is required, the emissivity is also possible to approach to 1 in this orthogonally-crossed 2D grating by optimizing one of the filling ratios, as shown in the right panel of Fig. 6(d). In our present design, the emissivity can reach 78% and 91% for two independent radiating wavelengths, which are obviously higher than 50% obtained by the checkboard structure [15

15. H. T. Miyazaki, K. Ikeda, T. Kasaya, K. Yamamoto, Y. Inoue, K. Fujimura, T. Kanakugi, M. Okada, K. Hatade, and S. Kitagawa, “Thermal emission of two-color polarized infrared waves from integrated plasmon cavities,” Appl. Phys. Lett. 92(14), 141114 (2008). [CrossRef]

].

At last, we calculate the E-field distribution at resonant wavelength for both x and y directions. As shown in the insets of Fig. 6(a), the field is localized in vicinity of the grating, revealing that SPP is excited respectively for both directions again.

4. Discussions

In addition, it is possible to obtain an emission containing more than two wavelengths if we arrange the structure properly. For example, a three-wavelength emitter can be obtained by arranging three 1D grating by 60° azimuthally. Of course, the interaction between them will be more complicated and the geometric parameters of the grating will be more difficult to be optimized. A useful method to optimize these parameters is the genetic algorithm (GA) [28

28. Z. Nichalewicz, Genetic Algorithms + Data Strucutres = Evolution Programs (Spring-Verlag, New York, 1992).

]. One thing we have to emphasize is that it is impossible to obtain the best geometric parameters by the simulation methods we introduce in our paper. We only propose how to optimize them. The important point here is that the emissivity can be much higher than 50% for both polarizations in our present design. There is still space to improve the emissivity if we use other methods such as GA to optimize the geometric parameters.

As the target of our paper is to obtain high emissivity for both x- and y-direction, higher emissivity is the most important point to be considered during the process of analyzing variation tendency and searching appropriate geometric parameters. The spectral coherence is considered secondly. If the purpose is to obtain better spectral coherence, the geometric parameters will be different. For example, as can be observed in Fig. 2, a shallower depth and smaller filling factor of the grating would lead to a narrower resonant peak, i.e. better spectral coherence. Provided that the depth of the grating is increased to ~λ/2, the space between neighbor ridges will evolve into microcavities and microcavity resonant modes will be induced [27

27. S. E. Han and D. J. Norris, “Beaming thermal emission from hot metallic bull’s eyes,” Opt. Express 18(5), 4829–4837 (2010). [CrossRef] [PubMed]

]. In that case, the polarization characteristic for both wavelengths will disappear. This is out of the range of this paper and we will not discuss here.

Finally, we consider the influence of the temperature since the application of the surface grating is for thermal source. All the above simulations have utilized the dielectric function of tungsten at 298K [18

18. J. H. Weaver, C. G. Olson, and D. W. Lynch, “Optical properties of crystalline tungsten,” Phys. Rev. B 12(4), 1293–1297 (1975). [CrossRef]

]. Based on the results in reference [27

27. S. E. Han and D. J. Norris, “Beaming thermal emission from hot metallic bull’s eyes,” Opt. Express 18(5), 4829–4837 (2010). [CrossRef] [PubMed]

], we fitted out the change of the dielectric constant with temperature and then applied it into our 1D grating. It was found that the peak wavelength red shifts with temperature slowly. The variation of the emissivity is not obvious although the FWHM of the peak increases, which leads to a decrease of quality factor Q (results not shown). These results are consistent with those demonstrated in reference [27

27. S. E. Han and D. J. Norris, “Beaming thermal emission from hot metallic bull’s eyes,” Opt. Express 18(5), 4829–4837 (2010). [CrossRef] [PubMed]

]. Furthermore, the geometric parameters were found to influence the emittance of the grating similarly under different temperature. As the main target in our paper is to obtain high emissivity which has been addressed in the above context, we expect that similar dual-wavelength orthogonally polarized radiation can also be generated in the wavelength range of ~3-4 μm at elevated temperature.

5. Conclusion

On the basis of the thermal emission from a 1D shallow tungsten grating, we proposed a 2D orthogonally-crossed shallow grating to produce dual-wavelength emission with orthogonally polarizations from a single surface. In the 1D grating, we found that there is optimum filling ratio and grating depth, with which the E-field is more intensively concentrated in vicinity of the air-tungsten interface when SPPs are excited and the thermal emission is higher. In the 2D orthogonally-crossed shallow grating, two wavelengths with an emissivity as high as 78% and 91% can be picked independently by optimizing its geometric parameters. Furthermore, the two wavelengths can be produced simultaneously if the polarization of the picking-polarizer is between 0° – 90°. Our investigations in this paper cannot only deliver understandings of the mechanism of enhancing thermal emission from complicatedly arranged shallow gratings, but also help us developing controllable multi-wavelength thermal radiation with high emissivity from a single surface.

Acknowledgment

The work was supported by the Project of High-level Professionals in the Universities of Guangdong Province and the National Natural Science Foundation (Grant No. 61378082).

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2.

C. Arnold, F. Marquier, M. Garin, F. Pardo, S. Collin, N. Bardou, J.-L. Pelouard, and J.-J. Greffet, “Coherent thermal infrared emission by two-dimensional silicon carbide gratings,” Phys. Rev. B 86(3), 035316 (2012). [CrossRef]

3.

S. Maruyama, T. Kashiwa, H. Yugami, and M. Esashi, “Thermal radiation from two-dimensionally confined modes in microcavities,” Appl. Phys. Lett. 79(9), 1393 (2001). [CrossRef]

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P. J. Hesketh, J. N. Zemel, and B. Gebhart, “Organ pipe radiant modes of periodic micromachined silicon surfaces,” Nature 324(6097), 549–551 (1986). [CrossRef]

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B. J. Lee and Z. M. Zhang, “Design and fabrication of planar multilayer structures with coherent thermal emission characteristics,” J. Appl. Phys. 100(6), 063529 (2006). [CrossRef]

6.

B. J. Lee, C. J. Fu, and Z. M. Zhang, “Coherent thermal emission from one-dimensional photonic crystals,” Appl. Phys. Lett. 87(7), 071904 (2005). [CrossRef]

7.

I. Celanovic, N. Jovanovic, and J. Kassakian, “Two-dimensional tungsten photonic crystals as selective thermal emitters,” Appl. Phys. Lett. 92(19), 193101 (2008). [CrossRef]

8.

W. Zhao, R. Biswas, I. Puscasu, and E. Johnson, “Angular variation of absorption and thermal emission from photonic crystals,” J. Opt. Soc. Am. B 26(9), 1808 (2009). [CrossRef]

9.

J. T. Wan and C. T. Chan, “Thermal emission by metallic photonic crystal slabs,” Appl. Phys. Lett. 89(4), 041915 (2006). [CrossRef]

10.

J. G. Fleming, S. Y. Lin, I. El-Kady, R. Biswas, and K. M. Ho, “All-metallic three-dimensional photonic crystals with a large infrared bandgap,” Nature 417(6884), 52–55 (2002). [CrossRef] [PubMed]

11.

J.-J. Greffet, R. Carminati, K. Joulain, J.-P. Mulet, S. Mainguy, and Y. Chen, “Coherent emission of light by thermal sources,” Nature 416(6876), 61–64 (2002). [CrossRef] [PubMed]

12.

M. Laroche, C. Arnold, F. Marquier, R. Carminati, J.-J. Greffet, S. Collin, N. Bardou, and J.-L. Pelouard, “Highly directional radiation generated by a tungsten thermal source,” Opt. Lett. 30(19), 2623–2625 (2005). [CrossRef] [PubMed]

13.

N. Nguyen-Huu, Y. B. Chen, and Y. L. Lo, “Development of a polarization-insensitive thermophotovoltaic emitter with a binary grating,” Opt. Express 20(6), 5882–5890 (2012). [CrossRef] [PubMed]

14.

Y.-B. Chen and Z. M. Zhang, “Design of tungsten complex gratings for thermophotovoltaic radiators,” Opt. Commun. 269(2), 411–417 (2007). [CrossRef]

15.

H. T. Miyazaki, K. Ikeda, T. Kasaya, K. Yamamoto, Y. Inoue, K. Fujimura, T. Kanakugi, M. Okada, K. Hatade, and S. Kitagawa, “Thermal emission of two-color polarized infrared waves from integrated plasmon cavities,” Appl. Phys. Lett. 92(14), 141114 (2008). [CrossRef]

16.

K. Masuno, T. Sawada, S. Kumagai, and M. Sasaki, “Multiwavelength Selective IR Emission Using Surface Plasmon Polaritons for Gas Sensing,” IEEE Photon. Technol. Lett. 23(22), 1661–1663 (2011). [CrossRef]

17.

A. D. Rakic, A. B. Djurisic, J. M. Elazar, and M. L. Majewski, “Optical properties of metallic films for vertical-cavity optoelectronic devices,” Appl. Opt. 37(22), 5271–5283 (1998). [CrossRef] [PubMed]

18.

J. H. Weaver, C. G. Olson, and D. W. Lynch, “Optical properties of crystalline tungsten,” Phys. Rev. B 12(4), 1293–1297 (1975). [CrossRef]

19.

C. Luo, A. Narayanaswamy, G. Chen, and J. D. Joannopoulos, “Thermal Radiation from Photonic Crystals: A Direct Calculation,” Phys. Rev. Lett. 93(21), 213905 (2004). [CrossRef] [PubMed]

20.

W. L. Barnes, A. Dereux, and T. W. Ebbesen, “Surface plasmon subwavelength optics,” Nature 424(6950), 824–830 (2003). [CrossRef] [PubMed]

21.

Z. J. Zhong, Y. Xu, S. Lan, Q.-F. Dai, and L. J. Wu, “Sharp and asymmetric transmission response in metal-dielectric-metal plasmonic waveguides containing Kerr nonlinear media,” Opt. Express 18(1), 79–86 (2010). [CrossRef] [PubMed]

22.

M. Kretschmann, T. A. Leskova, and A. A. Maradudin, “Conical Propagation of a Surface Polariton Across a Grating,” Opt. Commun. 215(4-6), 205–223 (2003). [CrossRef]

23.

H. Raether, Surface Plasmons (Springer, Berlin, 1988).

24.

E. Rephaeli and S. Fan, “Tungsten black absorber for solar light with wide angular operation range,” Appl. Phys. Lett. 92(21), 211107 (2008). [CrossRef]

25.

B. J. Lee, Y.-B. Chen, and Z. M. Zhang, “Confinement of infrared radiation to nanometer scales through metallic slit arrays,” J. Quant. Spectrosc. Radiat. Transf. 109(4), 608–619 (2008). [CrossRef]

26.

D. L. C. Chan, M. Soljacić, and J. D. Joannopoulos, “Thermal emission and design in 2D-periodic metallic photonic crystal slabs,” Opt. Express 14(19), 8785–8796 (2006). [CrossRef] [PubMed]

27.

S. E. Han and D. J. Norris, “Beaming thermal emission from hot metallic bull’s eyes,” Opt. Express 18(5), 4829–4837 (2010). [CrossRef] [PubMed]

28.

Z. Nichalewicz, Genetic Algorithms + Data Strucutres = Evolution Programs (Spring-Verlag, New York, 1992).

OCIS Codes
(050.2770) Diffraction and gratings : Gratings
(240.6680) Optics at surfaces : Surface plasmons
(260.3060) Physical optics : Infrared
(290.6815) Scattering : Thermal emission

ToC Category:
Diffraction and Gratings

History
Original Manuscript: August 20, 2013
Revised Manuscript: October 4, 2013
Manuscript Accepted: October 11, 2013
Published: November 13, 2013

Virtual Issues
Vol. 9, Iss. 1 Virtual Journal for Biomedical Optics

Citation
Fang Han, Xiangli Sun, Lijun Wu, and Qiang Li, "Dual-wavelength orthogonally polarized radiation generated by a tungsten thermal source," Opt. Express 21, 28570-28582 (2013)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-23-28570


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References

  1. J.-J. Greffet, “Applied physics: Controlled incandescence,” Nature478(7368), 191–192 (2011). [CrossRef] [PubMed]
  2. C. Arnold, F. Marquier, M. Garin, F. Pardo, S. Collin, N. Bardou, J.-L. Pelouard, and J.-J. Greffet, “Coherent thermal infrared emission by two-dimensional silicon carbide gratings,” Phys. Rev. B86(3), 035316 (2012). [CrossRef]
  3. S. Maruyama, T. Kashiwa, H. Yugami, and M. Esashi, “Thermal radiation from two-dimensionally confined modes in microcavities,” Appl. Phys. Lett.79(9), 1393 (2001). [CrossRef]
  4. P. J. Hesketh, J. N. Zemel, and B. Gebhart, “Organ pipe radiant modes of periodic micromachined silicon surfaces,” Nature324(6097), 549–551 (1986). [CrossRef]
  5. B. J. Lee and Z. M. Zhang, “Design and fabrication of planar multilayer structures with coherent thermal emission characteristics,” J. Appl. Phys.100(6), 063529 (2006). [CrossRef]
  6. B. J. Lee, C. J. Fu, and Z. M. Zhang, “Coherent thermal emission from one-dimensional photonic crystals,” Appl. Phys. Lett.87(7), 071904 (2005). [CrossRef]
  7. I. Celanovic, N. Jovanovic, and J. Kassakian, “Two-dimensional tungsten photonic crystals as selective thermal emitters,” Appl. Phys. Lett.92(19), 193101 (2008). [CrossRef]
  8. W. Zhao, R. Biswas, I. Puscasu, and E. Johnson, “Angular variation of absorption and thermal emission from photonic crystals,” J. Opt. Soc. Am. B26(9), 1808 (2009). [CrossRef]
  9. J. T. Wan and C. T. Chan, “Thermal emission by metallic photonic crystal slabs,” Appl. Phys. Lett.89(4), 041915 (2006). [CrossRef]
  10. J. G. Fleming, S. Y. Lin, I. El-Kady, R. Biswas, and K. M. Ho, “All-metallic three-dimensional photonic crystals with a large infrared bandgap,” Nature417(6884), 52–55 (2002). [CrossRef] [PubMed]
  11. J.-J. Greffet, R. Carminati, K. Joulain, J.-P. Mulet, S. Mainguy, and Y. Chen, “Coherent emission of light by thermal sources,” Nature416(6876), 61–64 (2002). [CrossRef] [PubMed]
  12. M. Laroche, C. Arnold, F. Marquier, R. Carminati, J.-J. Greffet, S. Collin, N. Bardou, and J.-L. Pelouard, “Highly directional radiation generated by a tungsten thermal source,” Opt. Lett.30(19), 2623–2625 (2005). [CrossRef] [PubMed]
  13. N. Nguyen-Huu, Y. B. Chen, and Y. L. Lo, “Development of a polarization-insensitive thermophotovoltaic emitter with a binary grating,” Opt. Express20(6), 5882–5890 (2012). [CrossRef] [PubMed]
  14. Y.-B. Chen and Z. M. Zhang, “Design of tungsten complex gratings for thermophotovoltaic radiators,” Opt. Commun.269(2), 411–417 (2007). [CrossRef]
  15. H. T. Miyazaki, K. Ikeda, T. Kasaya, K. Yamamoto, Y. Inoue, K. Fujimura, T. Kanakugi, M. Okada, K. Hatade, and S. Kitagawa, “Thermal emission of two-color polarized infrared waves from integrated plasmon cavities,” Appl. Phys. Lett.92(14), 141114 (2008). [CrossRef]
  16. K. Masuno, T. Sawada, S. Kumagai, and M. Sasaki, “Multiwavelength Selective IR Emission Using Surface Plasmon Polaritons for Gas Sensing,” IEEE Photon. Technol. Lett.23(22), 1661–1663 (2011). [CrossRef]
  17. A. D. Rakic, A. B. Djurisic, J. M. Elazar, and M. L. Majewski, “Optical properties of metallic films for vertical-cavity optoelectronic devices,” Appl. Opt.37(22), 5271–5283 (1998). [CrossRef] [PubMed]
  18. J. H. Weaver, C. G. Olson, and D. W. Lynch, “Optical properties of crystalline tungsten,” Phys. Rev. B12(4), 1293–1297 (1975). [CrossRef]
  19. C. Luo, A. Narayanaswamy, G. Chen, and J. D. Joannopoulos, “Thermal Radiation from Photonic Crystals: A Direct Calculation,” Phys. Rev. Lett.93(21), 213905 (2004). [CrossRef] [PubMed]
  20. W. L. Barnes, A. Dereux, and T. W. Ebbesen, “Surface plasmon subwavelength optics,” Nature424(6950), 824–830 (2003). [CrossRef] [PubMed]
  21. Z. J. Zhong, Y. Xu, S. Lan, Q.-F. Dai, and L. J. Wu, “Sharp and asymmetric transmission response in metal-dielectric-metal plasmonic waveguides containing Kerr nonlinear media,” Opt. Express18(1), 79–86 (2010). [CrossRef] [PubMed]
  22. M. Kretschmann, T. A. Leskova, and A. A. Maradudin, “Conical Propagation of a Surface Polariton Across a Grating,” Opt. Commun.215(4-6), 205–223 (2003). [CrossRef]
  23. H. Raether, Surface Plasmons (Springer, Berlin, 1988).
  24. E. Rephaeli and S. Fan, “Tungsten black absorber for solar light with wide angular operation range,” Appl. Phys. Lett.92(21), 211107 (2008). [CrossRef]
  25. B. J. Lee, Y.-B. Chen, and Z. M. Zhang, “Confinement of infrared radiation to nanometer scales through metallic slit arrays,” J. Quant. Spectrosc. Radiat. Transf.109(4), 608–619 (2008). [CrossRef]
  26. D. L. C. Chan, M. Soljacić, and J. D. Joannopoulos, “Thermal emission and design in 2D-periodic metallic photonic crystal slabs,” Opt. Express14(19), 8785–8796 (2006). [CrossRef] [PubMed]
  27. S. E. Han and D. J. Norris, “Beaming thermal emission from hot metallic bull’s eyes,” Opt. Express18(5), 4829–4837 (2010). [CrossRef] [PubMed]
  28. Z. Nichalewicz, Genetic Algorithms + Data Strucutres = Evolution Programs (Spring-Verlag, New York, 1992).

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