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Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 19, Iss. 15 — Jul. 18, 2011
  • pp: 14130–14136

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Low-loss Si3N4 arrayed-waveguide grating (de)multiplexer using nano-core optical waveguides

Daoxin Dai, Zhi Wang, Jared F. Bauters, M.-C. Tien, Martijn J. R. Heck, Daniel J. Blumenthal, and John E Bowers  »View Author Affiliations


Optics Express, Vol. 19, Issue 15, pp. 14130-14136 (2011)
http://dx.doi.org/10.1364/OE.19.014130


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Abstract

A 16-channel 200GHz arrayed-waveguide grating (AWG) (de)-multiplexer is demonstrated experimentally by utilizing Si3N4 buried optical waveguides, which have 50nm-thick Si3N4 cores and a 15μm-thick SiO2 cladding. The structure with an ultra-thin core layer helps to reduce the scattering due to the sidewall roughness and consequently shows very low loss of about 0.4~0.8dB/m. When using this type of optical waveguide for an AWG (de)multiplexer, there is no problem associated with gap refill using the upper-cladding material even when choosing a small (e.g., 1.0 μm) gap between adjacent arrayed waveguides, which helps to reduce the transition loss between the FPR (free-propagation region) and the arrayed waveguides. Therefore, the demonstrated AWG (de)multiplexer based on the present Si3N4 buried optical waveguides has a low on-chip loss. The fabricated AWG (de)multiplexer is characterized in two wavelength ranges around 1310nm and 1550nm, respectively. It shows that the crosstalk from adjacent and non-adjacent channels are about –30dB, and –40dB, respectively, at the wavelength range of 1310nm. The Si3N4 AWG (de)multiplexer has a temperature dependence of about 0.011nm/°C, which is close to that of a pure SiO2 AWG device.

© 2011 OSA

1. Introduction

As a promising technology for expanding the capacity of an optical communication system, wavelength division multiplexing (WDM) has been used widely in many applications, including optical communications. As a typical integrated (de)multiplexer used in a WDM system, the arrayed-waveguide grating (AWG) is important for many DWDM systems and modules [1

C. R. Doerr and K. Okamoto, “Advances in silica planar lightwave circuits,” J. Lightwave Technol. 24(12), 4763–4789 (2006). [CrossRef]

,2

Y. Hibino, “Recent advances in high-density and large-scale AWG multi/demultiplexers with higher index-contrast silica-based PLCs,” IEEE J. Sel. Top. Quantum Electron. 8(6), 1090–1101 (2002). [CrossRef]

]. In addition, AWGs have also been used for optical sensing [3

K. Kodate and Y. Komai, “Compact spectroscopic sensor using an arrayed waveguide grating,” J. Opt. A. 10(4), 044011–044018 (2008). [CrossRef]

] and optical spectrometers [4

P. Cheben, J. H. Schmid, A. Delâge, A. Densmore, S. Janz, B. Lamontagne, J. Lapointe, E. Post, P. Waldron, and D.-X. Xu, “A high-resolution silicon-on-insulator arrayed waveguide grating microspectrometer with sub-micrometer aperture waveguides,” Opt. Express 15(5), 2299–2306 (2007). [CrossRef] [PubMed]

]. Therefore, significant effort has been made to develop high-performance AWGs based on various materials and waveguide structures, e.g., silica-on-Si buried waveguides [5

R. Adar, M. R. Serbin, and V. Mizrahi, “Lss-than-1 dB per meter propagation loss of silica wave-guides measured using a ring-resonator,” J. Lightwave Technol. 12(8), 1369–1372 (1994). [CrossRef]

,6

A. Sugita, A. Kaneko, K. Okamoto, M. Itoh, A. Himeno, and Y. Ohmori, “Very low insertion loss arrayed-waveguide grating with vertically tapered waveguides,” IEEE Photon. Technol. Lett. 12(9), 1180–1182 (2000). [CrossRef]

], polymer waveguides [7

M. B. J. Diemeer, L. H. Spiekman, R. Ramsamoedj, and M. K. Smit, “Polymeric phased array wavelength multiplexer operating around 1550 nm,” Electron. Lett. 32(12), 1132–1133 (1996). [CrossRef]

,8

B. Yang, Y. Zhu, Y. Jiao, L. Yang, Z. Sheng, S. He, and D. Dai, “Compact Arrayed Waveguide Grating Devices Based on Small SU-8 Strip Waveguides,” J. Lightwave Technol. (to appear).

], InP ridge waveguides [9

Y. Barbarin, X. J. M. Leijtens, E. A. J. M. Bente, C. M. Louzao, J. R. Kooiman, and M. K. Smit, “Extremely small AWG demultiplexer fabricated on InP by using a double-etch process,” IEEE Photon. Technol. Lett. 16(11), 2478–2480 (2004). [CrossRef]

], large silicon-on-insulator (SOI) ridge waveguides [10

P. D. Trinh, S. Yegnanarayanan, F. Coppinger, and B. Jalali, “Silicon-on-insulator (SOI) phased-array wavelength multi/demultiplexer with extremely low-polarization sensitivity,” IEEE Photon. Technol. Lett. 9(7), 940–942 (1997). [CrossRef]

] as well as SOI (silicon-on-insulator) nanowires [11

W. Bogaerts, S. K. Selvaraja, P. Dumon, J. Brouckaert, K. De Vos, D. Van Thourhout, and R. Baets, “Silicon-on-insulator spectral filters fabricated with CMOS technology,” IEEE J. Sel. Top. Quantum Electron. 16(1), 33–44 (2010). [CrossRef]

,12

D. Dai, X. Fu, Y. Shi, and S. He, “Experimental demonstration of an ultracompact Si-nanowire-based reflective arrayed-waveguide grating (de)multiplexer with photonic crystal reflectors,” Opt. Lett. 35(15), 2594–2596 (2010). [CrossRef] [PubMed]

]. Silica AWG has been commercialized because of its high performance. However, the bending radius is usually very large because of the low index-contrast, which is not good for a high integration density. In contrast, SOI-nanowire has an ultra-high index contrast, which enables a micro-scale bending, and consequently ultrasmall SOI-nanowire AWGs have been intensively studied in the past years [11

W. Bogaerts, S. K. Selvaraja, P. Dumon, J. Brouckaert, K. De Vos, D. Van Thourhout, and R. Baets, “Silicon-on-insulator spectral filters fabricated with CMOS technology,” IEEE J. Sel. Top. Quantum Electron. 16(1), 33–44 (2010). [CrossRef]

-12

D. Dai, X. Fu, Y. Shi, and S. He, “Experimental demonstration of an ultracompact Si-nanowire-based reflective arrayed-waveguide grating (de)multiplexer with photonic crystal reflectors,” Opt. Lett. 35(15), 2594–2596 (2010). [CrossRef] [PubMed]

]. The drawback is that the SOI-nanowire AWG needs very high resolution fabrication technology and usually has a high insertion loss and high crosstalk. As an alternative platform with a moderate index contrast, Si3N4 waveguide is of interest [13

C. R. Doerr, L. Chen, L. L. Buhl, and Y.-K. Chen, “8-Channel SiO2/Si3N4/Si/Ge CWDM Receiver,” IEEE Photon. Technol. Lett. (to appear).

-14

C. R. Doerr, L. Chen, Y.-K. Chen, and L. L. Buhl, “Wide Bandwidth Silicon Nitride Grating Coupler,” IEEE Photon. Technol. Lett. 22(19), 1461–1463 (2010). [CrossRef]

]. In this paper, we demonstrate an AWG based on Si3N4 waveguides with a nano-core layer.

For AWGs, low loss is highly desirable, especially for applications in which low power consumption is required. When an AWG is connected with fibers, the fiber-to-chip coupling loss is one of the major loss origins, especially if the waveguide mode is not well-matched to the fiber mode. Nevertheless, this coupling loss could be minimized by using various mode converters [15

M. M. Spühler, B. J. Offrein, G. Bona, R. Germann, I. Massarek, and D. Erni, “A very short planar silica spot-size converter using a nonperiodic segmented waveguide,” J. Lightwave Technol. 16(9), 1680–1685 (1998). [CrossRef]

]. On the other hand, for an AWG integrated with other components on the same chip, the on-chip loss is usually more important. Therefore, in this paper we focus on the AWG’s on-chip loss, which includes the material loss, bending loss, waveguide scattering loss, and the transition loss between the FPR (free propagation region) and the arrayed waveguides. Usually the material loss can be minimized in the desired wavelength range by choosing the material appropriately. The bending loss can be reduced simply by choosing a large bending radius (even though small bending radius is desired to obtain a small footprint). Thus, in order to achieve a low-loss AWG, a reduction of the waveguide scattering and transition losses is essential.

The scattering loss can be reduced significantly by minimizing the roughness with an improved fabrication technology (especially the etching process). On the other hand, the scattering loss also depends on the optical field distribution, which can be modified by designing the waveguide structure. Since the top and bottom surfaces for a planar optical waveguide are much smoother than the sidewalls, the scattering loss is usually dominated by the sidewall roughness. It is expected to have a reduced scattering loss if a nano-scale core layer is used. In Ref [16

J. F. Bauters, M. J. R. Heck, D. John, D. Dai, M.-C. Tien, J. S. Barton, A. Leinse, R. G. Heideman, D. J. Blumenthal, and J. E. Bowers, “Ultra-low-loss high-aspect-ratio Si3N4 waveguides,” Opt. Express 19(4), 3163–3174 (2011). [CrossRef] [PubMed]

], we reported a low loss of 0.03dB/cm at 1550nm for 2-mm bend radius by using a buried optical waveguide which has a wide but ultra-thin Si3N4 core (2μm × 80nm). This provides a promising way to realize low-loss large-scale photonic integration circuits. In this paper, we demonstrate a low-loss AWG (de)multiplexer by using a thinner, lower loss optical waveguide with a 50nm-thick SiN core layer, and a loss of about 0.4~0.8dB/m [17

M. C. Tien, J. F. Bauters, M. J. Heck, D. J. Blumenthal, and J. E. Bowers, “Ultra-low loss Si3N4 waveguides with low nonlinearity and high power handling capability,” Opt. Express 18(23), 23562–23568 (2010). [CrossRef] [PubMed]

].

As mentioned earlier, the transition loss between the FPR and the arrayed waveguides is another important origin for the on-chip loss of an AWG [6

A. Sugita, A. Kaneko, K. Okamoto, M. Itoh, A. Himeno, and Y. Ohmori, “Very low insertion loss arrayed-waveguide grating with vertically tapered waveguides,” IEEE Photon. Technol. Lett. 12(9), 1180–1182 (2000). [CrossRef]

,18

Y. C. Zhu, F. H. Groen, D. H. P. Maat, Y. S. Oei, J. Romijin, and I. Moerman, “A compact PHASAR with low central channel loss,” in Proc. Euro. Conf. Integrated Optics ’99, Turin, Italy, Apr. 14–16, 219–222 (1999).

]. The transition loss is due to a field mismatch between the FPR and the arrayed waveguides because there are gaps between arrayed waveguides and the gap size is limited by the fabrication process. First, one usually cannot obtain a zero-gap because of the resolution limit of UV lithography. A potential solution is using e-beam lithography [18

Y. C. Zhu, F. H. Groen, D. H. P. Maat, Y. S. Oei, J. Romijin, and I. Moerman, “A compact PHASAR with low central channel loss,” in Proc. Euro. Conf. Integrated Optics ’99, Turin, Italy, Apr. 14–16, 219–222 (1999).

], which could make nano-scale gaps; however, the fabrication becomes very expensive and inefficient. For SiO2-on-Si AWGs in particular, the gaps are usually not allowed to be narrower than 2μm (which is not limited by UV lithography) so that one could refill the upper-cladding material into the gaps without voids. In order to reduce the transition loss, there are several approaches, e.g., using a double-etch technology, which has been used for AWGs based on InP waveguides [9

Y. Barbarin, X. J. M. Leijtens, E. A. J. M. Bente, C. M. Louzao, J. R. Kooiman, and M. K. Smit, “Extremely small AWG demultiplexer fabricated on InP by using a double-etch process,” IEEE Photon. Technol. Lett. 16(11), 2478–2480 (2004). [CrossRef]

], and SOI nanowires [11

W. Bogaerts, S. K. Selvaraja, P. Dumon, J. Brouckaert, K. De Vos, D. Van Thourhout, and R. Baets, “Silicon-on-insulator spectral filters fabricated with CMOS technology,” IEEE J. Sel. Top. Quantum Electron. 16(1), 33–44 (2010). [CrossRef]

]. Another similar approach of using vertical tapers is introduced at the junctions and the transition loss could be reduced by 1dB [6

A. Sugita, A. Kaneko, K. Okamoto, M. Itoh, A. Himeno, and Y. Ohmori, “Very low insertion loss arrayed-waveguide grating with vertically tapered waveguides,” IEEE Photon. Technol. Lett. 12(9), 1180–1182 (2000). [CrossRef]

]. However, the fabrication is not easy.

The waveguide reported in this paper has an ultra-thin core layer, and so it becomes very easy to refill the upper-cladding material into the gaps even when the gap width is reduced to less than 2μm. Considering the resolution limitation of the UV-lithography process, in our design we choose 1-μm-wide gaps, and a low-loss AWG is achieved as the experimental results show below. In addition, the ultra-thin core layer allows a singlemode optical waveguide to be as wide as several microns even though the Si3N4 core has much higher refractive index than the SiO2 cladding. Since a wider optical waveguide is more tolerant to the width variation, the present wide Si3N4 optical waveguide also helps to obtain a low-crosstalk AWG (de)multiplexer. Table 1 shows a comparison for AWGs on various platforms, including SiO2, SOI, InP, polymer as well as Si3N4 in the present paper. From this comparison, one sees that the present Si3N4 platform is a good option for realizing AWGs with good performances.

Table 1  Comparison for AWGs on various platforms.
(non)adjacent crosstalkon-chip lossChannel number ×channel spacingWaveguide sizeFootprint
SiO2WG [6

A. Sugita, A. Kaneko, K. Okamoto, M. Itoh, A. Himeno, and Y. Ohmori, “Very low insertion loss arrayed-waveguide grating with vertically tapered waveguides,” IEEE Photon. Technol. Lett. 12(9), 1180–1182 (2000). [CrossRef]

]		     ~–40dB0.75dB32 × 100GHz6μm × 6μm     –
Polymer buried WG [7

M. B. J. Diemeer, L. H. Spiekman, R. Ramsamoedj, and M. K. Smit, “Polymeric phased array wavelength multiplexer operating around 1550 nm,” Electron. Lett. 32(12), 1132–1133 (1996). [CrossRef]

]		     ~–25dB~8dB8 × 400GHz6μm × 6μm6.4cm × 1.4cm
Polymer strip WG [8

B. Yang, Y. Zhu, Y. Jiao, L. Yang, Z. Sheng, S. He, and D. Dai, “Compact Arrayed Waveguide Grating Devices Based on Small SU-8 Strip Waveguides,” J. Lightwave Technol. (to appear).

]		     ~–20dB~5dB23 × 400GHz2μm × 1.5μm0.22cm × 0.47cm
InP [9

Y. Barbarin, X. J. M. Leijtens, E. A. J. M. Bente, C. M. Louzao, J. R. Kooiman, and M. K. Smit, “Extremely small AWG demultiplexer fabricated on InP by using a double-etch process,” IEEE Photon. Technol. Lett. 16(11), 2478–2480 (2004). [CrossRef]

]		     ~–12dB<5dB4 × 400GHz2μm × 0.72μm230μm × 330μm
SOI rib WG [10

P. D. Trinh, S. Yegnanarayanan, F. Coppinger, and B. Jalali, “Silicon-on-insulator (SOI) phased-array wavelength multi/demultiplexer with extremely low-polarization sensitivity,” IEEE Photon. Technol. Lett. 9(7), 940–942 (1997). [CrossRef]

]		     ~–22~6dB4 × 240GHz– × 5μm2.7cm × 2.7cm
SOI nanowire [12

D. Dai, X. Fu, Y. Shi, and S. He, “Experimental demonstration of an ultracompact Si-nanowire-based reflective arrayed-waveguide grating (de)multiplexer with photonic crystal reflectors,” Opt. Lett. 35(15), 2594–2596 (2010). [CrossRef] [PubMed]

]		     ~–12dB~3dB9 × 400GHz500nm × 220nm134μm × 115μm
SiN WG (this work)    <–30dB      (~–40dB)~<0.5dB16 × 200GHz5.5μm × 50nm2cm × 1.5cm

2. Design, fabrication and characterization

Figure 1(a) shows the cross section of the present buried Si3N4 optical waveguides, which have a wide and ultrathin Si3N4 core (about 50nm thick). The SiO2 lower-cladding has a thickness of 15μm to avoid any leakage loss to the substrate. The SiO2 upper-cladding is also 15μm-thick to make the waveguide symmetrical. The waveguides and devices were fabricated with LioniX BV’s TriPleXTM technology [16

J. F. Bauters, M. J. R. Heck, D. John, D. Dai, M.-C. Tien, J. S. Barton, A. Leinse, R. G. Heideman, D. J. Blumenthal, and J. E. Bowers, “Ultra-low-loss high-aspect-ratio Si3N4 waveguides,” Opt. Express 19(4), 3163–3174 (2011). [CrossRef] [PubMed]

]. The process begins with the thermal oxidation of a standard silicon wafer form the lower cladding. This is followed by LPCVD deposition of stoichiometric Si3N4. A single photolithography step is then performed followed by reactive ion etching to form the ridge waveguide. Finally, a thick SiO2 layer is deposited using plasma-enhanced CVD (PECVD) to complete the upper cladding layer. The refractive indices for the Si3N4 core and SiO2 cladding are about 1.99 and 1.45, respectively. In this structure, the sidewall area is very small and consequently the overlap of the optical field with the sidewall is minimized, which is helpful to reduce the scattering loss from the roughness of the sidewall. Figure 1 (b) and 1(c) show the profiles for TE- and TM- polarized fundamental mode fields, which are from the full-vectorial FEM (finite-element method) mode solver. For the present Si3N4 waveguide, the TM polarized mode has a much weaker confinement than the TE polarized mode. Consequently the bending loss of TM polarization is much higher than TE polarization. Therefore, in this paper we only consider operation with TE polarization.

Fig. 1 (a). The cross section of the present low-loss buried optical waveguide with a 50nm-thick Si3N4 core; (b) the mode profile of the TE-polarized fundamental mode; (c) the mode profile of the TM-polarized fundamental mode.

For the AWG design, we choose the following parameters: the central wavelength λ 0 = 1550nm, the channel number N ch = 16 and the channel spacing Δλ ch = 1.6nm (200GHz), the number of arrayed waveguides N WG = 150, the diffraction order m = 60, the FPR length L FPR = 3000μm, and the end separation of the output waveguides d g = 20μm. Figure 2 shows the layout of the designed AWG (de)multiplexer. Two reference waveguides are put at the bottom of the AWG for normalizing the AWG’s response. The total size is about 2cm × 1.5cm, which is comparable to a conventional SiO2 AWG. It is possible to reduce the footprint by choosing a relatively thick Si3N4 core layer (e.g., 100nm~200nm) so that the minimal bending radius could be reduced to sub-millimeter. Here we choose the Si3N4 thickness as 50nm in order to be compatible to the design for ultra-low loss waveguiding in the same wafer.

Fig. 2 The layout of the designed AWG (de)multiplexer.

In order to characterize the fabricated AWG, we use a measurement setup consisting of a free-space optical system with a bulk polarizer to have a TE-polarized input light at the input side [ 19

D. Dai, Z. Wang, N. Julian, and J. E. Bowers, “Compact broadband polarizer based on shallowly-etched silicon-on-insulator ridge optical waveguides,” Opt. Express 18(26), 27404–27415 (2010). [CrossRef] [PubMed]

]. A lens fiber was used for the coupling and the coupling loss is less than 2dB/facet for a 5.5μm-wide input/output waveguide. Figure 3(a) shows the measured spectral responses in the wavelength range from 1510nm to 1610nm by using a tunable laser and a photodetector. The tunable laser was tuned with a step of 0.1nm. The responses are normalized by the transmission of the reference waveguide. It can be seen that the spectral response is repeated over a wavelength span, which is called free spectral range (FSR). The FSR is about 25.3nm for the AWG device. The channel spacing is about 1.58nm, which is very close to the designed value (1.6nm). Therefore, there are 16 channels available in a FSR. From the normalized responses shown in Fig. 3(a), it can be seen that the excess loss of the fabricated AWG is low (almost zero for the central channel), which is mainly due to the small gap between the arrayed waveguides and good refilling of the upper-cladding layer because of the core layer is very thin. Figure 3(b) shows the responses of the central channel (#8). From this figure, one can see that the crosstalk from the adjacent channels is about –25dB while the non-adjacent crosstalk is as low as –30dB. We also note that there are two significant sidelobes at both sides of the major peak. These two sidelobes are due to the coupling between the adjacent output waveguides.

Fig. 3 (a). The measured spectral responses of all the channels in the wavelength range around 1550nm; (b) the response for channel

When the wavelength becomes shorter, the optical confinement of the Si3N4 optical waveguide becomes stronger and consequently the coupling between adjacent output waveguides is reduced. Therefore the sidelobes are expected to be smaller. Here we also measure the AWG’s responses in a short wavelength range from 1280nm to 1360nm by using an ASE light source along with an optical spectral analyzer (OSA) whose resolution is 0.1nm. Figure 4(a) shows the measured spectral responses of all the channels in the wavelength range from 1310nm to 1335nm. These spectral responses are normalized by the transmission of the reference waveguide. In this case, the FSR of the AWG becomes 18.4nm because of the shorter operation wavelength and the channel spacing is about 1.34nm, which is smaller than that in the wavelength range around 1550nm. Consequently, only 13 channels are available in a FSR. The central channels have very low excess loss. For the outer channels, the loss is higher due to the envelope of the far field [20

Y. Sakamaki, S. Kamei, T. Hashimoto, T. Kitoh, and H. Takahashi, “Loss uniformity improvement of arrayed-waveguide grating with mode-field converters designed by wavefront matching method,” J. Lightwave Technol. 27(24), 5710–5715 (2009). [CrossRef]

]. Figure 4(b) shows the response of the central channel. From this figure, one sees that the crosstalk from the adjacent channel is less than –30dB, and the non-adjacent channel crosstalk is about –40dB.

Fig. 4 (a). The measured spectral responses of all the channels in the wavelength range around 1310nm; (b) the response for channel #9. The OSA resolution is 0.1nm in the measurement.

We also characterize the temperature dependence of the presented AWG.

Figure 5(a) shows the measured spectral response of the central channel (#9) when the substrate temperature is set as 10, 40, 70, and 100°C, respectively. It can be seen that the central wavelength increases as the temperature increases. Since the present Si3N4 waveguide has a 50nm-thick core surrounded by a thick SiO2 cladding, most power of the fundamental mode is confined in the SiO2 cladding and consequently the thermal performance is expected to be very similar to a pure SiO2 buried waveguide.

Fig. 5 (a). The spectral response of channel #9 as the temperature varies; (b) the central wavelength of channel #9 as the temperature increases from 10 to 100°C.

Figure 5(b) shows the central wavelength as the temperature varies. And the slope is about ∆λ/∆T = 0.011 nm/°C, which is very close to that of an AWG based on pure SiO2 buried waveguides as expected.

3. Conclusions

In this paper, we have demonstrated a low-loss, low-crosstalk AWG (de)multiplexer by using Si3N4 buried optical waveguides. The presented AWG (de)multiplexer has 16 channels and the channel spacing is 200GHz (i.e., 1.6nm). The singlemode Si3N4 optical waveguide used here has a 5.5μm × 50nm Si3N4 core and a 15μm-thick SiO2 cladding. With such a structure, the Si3N4 optical waveguide has a very low scattering loss due to small mode overlap with the sidewall roughness. For the design of an AWG (de)multiplexer, we have chosen a small gap (about 1μm-wide) between adjacent arrayed waveguides to reduce the transition loss between the FPR and the arrayed waveguides. The fabricated AWG (de)multiplexer has been characterized in two wavelength ranges around 1310nm, and 1550nm, respectively. At the shorter wavelength range, the optical confinement becomes stronger and consequently the crosstalk is lower than that at longer wavelengths. It has shown that the crosstalk of adjacent and non-adjacent channels are about –30dB, and –40dB, respectively, at the wavelength range of 1310nm. The design could be optimized further to improve the AWG performance at longer wavelength by choosing a thicker core (e.g., 100~200nm). Finally we have also characterized the temperature dependence of the fabricated Si3N4 AWG (de)multiplexer and the temperature dependence is about 0.011nm/°C, which is close to that of a pure SiO2 AWG device because most power of the fundamental mode is confined in the SiO2 cladding.

Acknowledgements

This work was supported by DARPA MTO under the iPhoD contract No: HR0011-09-C-0123. The authors thank Scott Rodgers, Demis John and John Barton for useful discussions. The optical waveguides were fabricated by LioniX BV, Netherlands.

References and links

1.

C. R. Doerr and K. Okamoto, “Advances in silica planar lightwave circuits,” J. Lightwave Technol. 24(12), 4763–4789 (2006). [CrossRef]

2.

Y. Hibino, “Recent advances in high-density and large-scale AWG multi/demultiplexers with higher index-contrast silica-based PLCs,” IEEE J. Sel. Top. Quantum Electron. 8(6), 1090–1101 (2002). [CrossRef]

3.

K. Kodate and Y. Komai, “Compact spectroscopic sensor using an arrayed waveguide grating,” J. Opt. A. 10(4), 044011–044018 (2008). [CrossRef]

4.

P. Cheben, J. H. Schmid, A. Delâge, A. Densmore, S. Janz, B. Lamontagne, J. Lapointe, E. Post, P. Waldron, and D.-X. Xu, “A high-resolution silicon-on-insulator arrayed waveguide grating microspectrometer with sub-micrometer aperture waveguides,” Opt. Express 15(5), 2299–2306 (2007). [CrossRef] [PubMed]

5.

R. Adar, M. R. Serbin, and V. Mizrahi, “Lss-than-1 dB per meter propagation loss of silica wave-guides measured using a ring-resonator,” J. Lightwave Technol. 12(8), 1369–1372 (1994). [CrossRef]

6.

A. Sugita, A. Kaneko, K. Okamoto, M. Itoh, A. Himeno, and Y. Ohmori, “Very low insertion loss arrayed-waveguide grating with vertically tapered waveguides,” IEEE Photon. Technol. Lett. 12(9), 1180–1182 (2000). [CrossRef]

7.

M. B. J. Diemeer, L. H. Spiekman, R. Ramsamoedj, and M. K. Smit, “Polymeric phased array wavelength multiplexer operating around 1550 nm,” Electron. Lett. 32(12), 1132–1133 (1996). [CrossRef]

8.

B. Yang, Y. Zhu, Y. Jiao, L. Yang, Z. Sheng, S. He, and D. Dai, “Compact Arrayed Waveguide Grating Devices Based on Small SU-8 Strip Waveguides,” J. Lightwave Technol. (to appear).

9.

Y. Barbarin, X. J. M. Leijtens, E. A. J. M. Bente, C. M. Louzao, J. R. Kooiman, and M. K. Smit, “Extremely small AWG demultiplexer fabricated on InP by using a double-etch process,” IEEE Photon. Technol. Lett. 16(11), 2478–2480 (2004). [CrossRef]

10.

P. D. Trinh, S. Yegnanarayanan, F. Coppinger, and B. Jalali, “Silicon-on-insulator (SOI) phased-array wavelength multi/demultiplexer with extremely low-polarization sensitivity,” IEEE Photon. Technol. Lett. 9(7), 940–942 (1997). [CrossRef]

11.

W. Bogaerts, S. K. Selvaraja, P. Dumon, J. Brouckaert, K. De Vos, D. Van Thourhout, and R. Baets, “Silicon-on-insulator spectral filters fabricated with CMOS technology,” IEEE J. Sel. Top. Quantum Electron. 16(1), 33–44 (2010). [CrossRef]

12.

D. Dai, X. Fu, Y. Shi, and S. He, “Experimental demonstration of an ultracompact Si-nanowire-based reflective arrayed-waveguide grating (de)multiplexer with photonic crystal reflectors,” Opt. Lett. 35(15), 2594–2596 (2010). [CrossRef] [PubMed]

13.

C. R. Doerr, L. Chen, L. L. Buhl, and Y.-K. Chen, “8-Channel SiO2/Si3N4/Si/Ge CWDM Receiver,” IEEE Photon. Technol. Lett. (to appear).

14.

C. R. Doerr, L. Chen, Y.-K. Chen, and L. L. Buhl, “Wide Bandwidth Silicon Nitride Grating Coupler,” IEEE Photon. Technol. Lett. 22(19), 1461–1463 (2010). [CrossRef]

15.

M. M. Spühler, B. J. Offrein, G. Bona, R. Germann, I. Massarek, and D. Erni, “A very short planar silica spot-size converter using a nonperiodic segmented waveguide,” J. Lightwave Technol. 16(9), 1680–1685 (1998). [CrossRef]

16.

J. F. Bauters, M. J. R. Heck, D. John, D. Dai, M.-C. Tien, J. S. Barton, A. Leinse, R. G. Heideman, D. J. Blumenthal, and J. E. Bowers, “Ultra-low-loss high-aspect-ratio Si3N4 waveguides,” Opt. Express 19(4), 3163–3174 (2011). [CrossRef] [PubMed]

17.

M. C. Tien, J. F. Bauters, M. J. Heck, D. J. Blumenthal, and J. E. Bowers, “Ultra-low loss Si3N4 waveguides with low nonlinearity and high power handling capability,” Opt. Express 18(23), 23562–23568 (2010). [CrossRef] [PubMed]

18.

Y. C. Zhu, F. H. Groen, D. H. P. Maat, Y. S. Oei, J. Romijin, and I. Moerman, “A compact PHASAR with low central channel loss,” in Proc. Euro. Conf. Integrated Optics ’99, Turin, Italy, Apr. 14–16, 219–222 (1999).

19.

D. Dai, Z. Wang, N. Julian, and J. E. Bowers, “Compact broadband polarizer based on shallowly-etched silicon-on-insulator ridge optical waveguides,” Opt. Express 18(26), 27404–27415 (2010). [CrossRef] [PubMed]

20.

Y. Sakamaki, S. Kamei, T. Hashimoto, T. Kitoh, and H. Takahashi, “Loss uniformity improvement of arrayed-waveguide grating with mode-field converters designed by wavefront matching method,” J. Lightwave Technol. 27(24), 5710–5715 (2009). [CrossRef]

OCIS Codes
(130.0130) Integrated optics : Integrated optics
(230.7390) Optical devices : Waveguides, planar

ToC Category:
Integrated Optics

History
Original Manuscript: May 18, 2011
Revised Manuscript: June 7, 2011
Manuscript Accepted: June 7, 2011
Published: July 8, 2011

Citation
Daoxin Dai, Zhi Wang, Jared F. Bauters, M.-C. Tien, Martijn J. R. Heck, Daniel J. Blumenthal, and John E Bowers, "Low-loss Si3N4 arrayed-waveguide grating (de)multiplexer using nano-core optical waveguides," Opt. Express 19, 14130-14136 (2011)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-15-14130


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References

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  2. Y. Hibino, “Recent advances in high-density and large-scale AWG multi/demultiplexers with higher index-contrast silica-based PLCs,” IEEE J. Sel. Top. Quantum Electron. 8(6), 1090–1101 (2002). [CrossRef]
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  5. R. Adar, M. R. Serbin, and V. Mizrahi, “Lss-than-1 dB per meter propagation loss of silica wave-guides measured using a ring-resonator,” J. Lightwave Technol. 12(8), 1369–1372 (1994). [CrossRef]
  6. A. Sugita, A. Kaneko, K. Okamoto, M. Itoh, A. Himeno, and Y. Ohmori, “Very low insertion loss arrayed-waveguide grating with vertically tapered waveguides,” IEEE Photon. Technol. Lett. 12(9), 1180–1182 (2000). [CrossRef]
  7. M. B. J. Diemeer, L. H. Spiekman, R. Ramsamoedj, and M. K. Smit, “Polymeric phased array wavelength multiplexer operating around 1550 nm,” Electron. Lett. 32(12), 1132–1133 (1996). [CrossRef]
  8. B. Yang, Y. Zhu, Y. Jiao, L. Yang, Z. Sheng, S. He, and D. Dai, “Compact Arrayed Waveguide Grating Devices Based on Small SU-8 Strip Waveguides,” J. Lightwave Technol. (to appear).
  9. Y. Barbarin, X. J. M. Leijtens, E. A. J. M. Bente, C. M. Louzao, J. R. Kooiman, and M. K. Smit, “Extremely small AWG demultiplexer fabricated on InP by using a double-etch process,” IEEE Photon. Technol. Lett. 16(11), 2478–2480 (2004). [CrossRef]
  10. P. D. Trinh, S. Yegnanarayanan, F. Coppinger, and B. Jalali, “Silicon-on-insulator (SOI) phased-array wavelength multi/demultiplexer with extremely low-polarization sensitivity,” IEEE Photon. Technol. Lett. 9(7), 940–942 (1997). [CrossRef]
  11. W. Bogaerts, S. K. Selvaraja, P. Dumon, J. Brouckaert, K. De Vos, D. Van Thourhout, and R. Baets, “Silicon-on-insulator spectral filters fabricated with CMOS technology,” IEEE J. Sel. Top. Quantum Electron. 16(1), 33–44 (2010). [CrossRef]
  12. D. Dai, X. Fu, Y. Shi, and S. He, “Experimental demonstration of an ultracompact Si-nanowire-based reflective arrayed-waveguide grating (de)multiplexer with photonic crystal reflectors,” Opt. Lett. 35(15), 2594–2596 (2010). [CrossRef] [PubMed]
  13. C. R. Doerr, L. Chen, L. L. Buhl, and Y.-K. Chen, “8-Channel SiO2/Si3N4/Si/Ge CWDM Receiver,” IEEE Photon. Technol. Lett. (to appear).
  14. C. R. Doerr, L. Chen, Y.-K. Chen, and L. L. Buhl, “Wide Bandwidth Silicon Nitride Grating Coupler,” IEEE Photon. Technol. Lett. 22(19), 1461–1463 (2010). [CrossRef]
  15. M. M. Spühler, B. J. Offrein, G. Bona, R. Germann, I. Massarek, and D. Erni, “A very short planar silica spot-size converter using a nonperiodic segmented waveguide,” J. Lightwave Technol. 16(9), 1680–1685 (1998). [CrossRef]
  16. J. F. Bauters, M. J. R. Heck, D. John, D. Dai, M.-C. Tien, J. S. Barton, A. Leinse, R. G. Heideman, D. J. Blumenthal, and J. E. Bowers, “Ultra-low-loss high-aspect-ratio Si3N4 waveguides,” Opt. Express 19(4), 3163–3174 (2011). [CrossRef] [PubMed]
  17. M. C. Tien, J. F. Bauters, M. J. Heck, D. J. Blumenthal, and J. E. Bowers, “Ultra-low loss Si3N4 waveguides with low nonlinearity and high power handling capability,” Opt. Express 18(23), 23562–23568 (2010). [CrossRef] [PubMed]
  18. Y. C. Zhu, F. H. Groen, D. H. P. Maat, Y. S. Oei, J. Romijin, and I. Moerman, “A compact PHASAR with low central channel loss,” in Proc. Euro. Conf. Integrated Optics ’99, Turin, Italy, Apr. 14–16, 219–222 (1999).
  19. D. Dai, Z. Wang, N. Julian, and J. E. Bowers, “Compact broadband polarizer based on shallowly-etched silicon-on-insulator ridge optical waveguides,” Opt. Express 18(26), 27404–27415 (2010). [CrossRef] [PubMed]
  20. Y. Sakamaki, S. Kamei, T. Hashimoto, T. Kitoh, and H. Takahashi, “Loss uniformity improvement of arrayed-waveguide grating with mode-field converters designed by wavefront matching method,” J. Lightwave Technol. 27(24), 5710–5715 (2009). [CrossRef]

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