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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 19, Iss. 14 — Jul. 4, 2011
  • pp: 13557–13564
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Continuously tunable slow-light device consisting of heater-controlled silicon microring array

Fumihiro Shinobu, Norihiro Ishikura, Yoshiki Arita, Takemasa Tamanuki, and Toshihiko Baba  »View Author Affiliations


Optics Express, Vol. 19, Issue 14, pp. 13557-13564 (2011)
http://dx.doi.org/10.1364/OE.19.013557


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Abstract

We experimentally demonstrate a tunable slow-light device consisting of all-pass Si microrings. A compact device of 0.014 mm2 footprint is fabricated by using CMOS-compatible process, and its center wavelength, bandwidth and delay are continuously tuned by integrated heaters. The tuning range is 300 ps at fixed wavelengths with a 1 nm bandwidth. Eye opening of 40 Gbps non-return-to-zero signals is observed at up to a 150 ps delay and a 4 bit buffering capacity is confirmed, which corresponds to a spatial buffering density of 0.29 kbit/mm2.

© 2011 OSA

1. Introduction

Optically tunable delay lines will be applicable for optical buffering, retiming and multi/demultiplexing of pulses, fast pump-probe and correlation measurements, and so on, if they realize wide-range and high-speed tuning of the delay at desired wavelengths while maintaining sufficiently low dispersion [1

1. R. S. Tucker, P.-C. Ku, and C. Chang-Hasnain, “Slow-light optical buffers - capabilities and fundamental limitations,” J. Lightwave Technol. 23(12), 4046–4066 (2005). [CrossRef]

]. A long delay of over 100 ns is necessary for optical buffering in packet switching, while a 100 ps order delay is already usable in other applications. Aiming for such a delay on a chip, photonic crystal slow light devices have been studied, which greatly reduce the group velocity of light and controls the delay on demand [2

2. T. Baba, “Slow light in photonic crystals,” Nat. Photonics 2(8), 465–473 (2008). [CrossRef]

]. Here, the localized laser heating deconcentrates the slow light condition spectrally so that the slow light bandwidth is expanded and the delay is reduced accordingly [3

3. T. Baba, T. Kawaaski, H. Sasaki, J. Adachi, and D. Mori, “Large delay-bandwidth product and tuning of slow light pulse in photonic crystal coupled waveguide,” Opt. Express 16(12), 9245–9253 (2008). [CrossRef] [PubMed]

]. For example, 250-μm long photonic crystal coupled waveguides on silicon-on-insulator (SOI) substrate achieved a tuning range of up to 100 ps and a tunable buffering capacity of 22 bits for pulses of several picoseconds [4

4. J. Adachi, N. Ishikura, H. Sasaki, and T. Baba, “Wide range tuning of slow light pulse in SOI photonic crystal coupled waveguide via folded chirping,” IEEE J. Sel. Top. Quantum Electron. 16(1), 192–199 (2010). [CrossRef]

]. A common issue in photonic crystal devices is that they usually employ an airbridge slab structure for the strong optical confinement. It is not straightforward to fabricate the airbridge slab simultaneously with fiber couplers, heaters, PIN junctions, and other waveguide components in Si photonics, and hence this limits the functions added to the delay line. An alternative approach is to use microring resonators in the configurations of all pass filters [5

5. J. Yang, N. K. Fontaine, Z. Pan, A. O. Karalar, S. S. Djordjevic, C. Yang, W. Chen, S. Chu, B. E. Little, and S. J. B. Yoo, “Continuously tunable, wavelength-selective buffering in optical packet switching network,” IEEE Photon. Technol. Lett. 20(12), 1030–1032 (2008). [CrossRef]

7

7. J. Cardenas, M. A. Foster, N. Sherwood-Droz, C. B. Poitras, H. L. R. Lira, B. Zhang, A. L. Gaeta, J. B. Khurgin, P. Morton, and M. Lipson, “Wide-bandwidth continuously tunable optical delay line using silicon microring resonators,” Opt. Express 18(25), 26525–26534 (2010). [CrossRef] [PubMed]

] or the mixture of all pass filters and coupled-resonator optical waveguides (CROWs) [8

8. A. Melloni, F. Morichetti, C. Ferrari, and M. Martinelli, “Continuously tunable 1 byte delay in coupled-resonator optical waveguides,” Opt. Lett. 33(20), 2389–2391 (2008). [CrossRef] [PubMed]

,9

9. A. Melloni, A. Canciamilla, C. Ferrari, F. Morichetti, L. O'Faolain, T. F. Krauss, R. De La Rue, A. Samarelli, and M. Sorel, “Tunable delay lines in silicon photonics: coupled resonators and photonic crystals, a comparison,” IEEE Photon. J. 2(2), 181–194 (2010). [CrossRef]

]. They also control the delay by locally heating some of multiple rings. A tuning range of up to a few nanoseconds and a tunable buffering capacity of up to 8 bits have been reported for devices in different material systems.

In this study, we focus on Si microring all pass filters, as schematically illustrated in Fig. 1
Fig. 1 Schematics of all-pass-type microring array (upper figure) and delay spectrum (lower figure). (a) Single ring model. (b) Multi-ring model with uniform index profile and the same resonant wavelength. (c) Multi-ring model with sloped index profile and detuned resonant wavelengths forming an envelope spectrum.
, because of the following three reasons: (1) high-quality fabrication of Si microrings is available using CMOS-compatible process; (2) the spatial buffering density of Si microrings is higher than those of lower-index-contrast systems, as discussed later; and (3) even with some disordering and imperfection, all pass filters exhibit the smoother spectral characteristics than in CROWs (CROWs usually exhibit a noisy spectrum caused by the small fluctuation in the coupling strength between rings particularly with a high-index contrast). For such a device, fixed delays have been studied for single ring [10

10. Q. Li, F. Liu, Z. Zhang, M. Qiu, and Y. Su, “System performances of on-chip silicon microring delay line for RZ, CSRZ, RZ-DB and RZ-AMI signals,” J. Lightwave Technol. 26(23), 3744–3751 (2008). [CrossRef]

] and multiple rings [11

11. F. Xia, L. Sekaric, and Y. Vlasov, “Ultracompact optical buffers on a silicon chip,” Nat. Photonics 1(1), 65–71 (2007). [CrossRef]

]. Tunable delay has also been reported [6

6. W. M. J. Green, H. F. Hamann, L. Sekaric, M. J. Rooks, and Y. A. Vlasov, “Ultra-compact reconfigurable silicon optical devices using micron-scale localized thermal heating,” Tech. Dig. Opt. Fiber Commun. Conf., OtuM3 (2007).

,7

7. J. Cardenas, M. A. Foster, N. Sherwood-Droz, C. B. Poitras, H. L. R. Lira, B. Zhang, A. L. Gaeta, J. B. Khurgin, P. Morton, and M. Lipson, “Wide-bandwidth continuously tunable optical delay line using silicon microring resonators,” Opt. Express 18(25), 26525–26534 (2010). [CrossRef] [PubMed]

]. In particular, Ref. [7

7. J. Cardenas, M. A. Foster, N. Sherwood-Droz, C. B. Poitras, H. L. R. Lira, B. Zhang, A. L. Gaeta, J. B. Khurgin, P. Morton, and M. Lipson, “Wide-bandwidth continuously tunable optical delay line using silicon microring resonators,” Opt. Express 18(25), 26525–26534 (2010). [CrossRef] [PubMed]

]. maintains a low-dispersion condition by the balanced detuning of eight rings and demonstrates a tunable capacity of < 2 bits for 10 Gbps signals. Our approach is similar but simpler than this. We integrate many rings, each of which has the same group delay spectrum. Even though small disordering occurs in each ring, the statistical distribution of the spectral detuning is expected to form a smooth envelope spectrum with a maximum delay. The delay is reduced from this value by intentionally detuning some rings further so that the envelope delay spectrum is expanded in the same manner as in the photonic crystal devices. For the intentional detuning, we also use localized heating. Here, we do not prepare a heater for every ring [6

6. W. M. J. Green, H. F. Hamann, L. Sekaric, M. J. Rooks, and Y. A. Vlasov, “Ultra-compact reconfigurable silicon optical devices using micron-scale localized thermal heating,” Tech. Dig. Opt. Fiber Commun. Conf., OtuM3 (2007).

,7

7. J. Cardenas, M. A. Foster, N. Sherwood-Droz, C. B. Poitras, H. L. R. Lira, B. Zhang, A. L. Gaeta, J. B. Khurgin, P. Morton, and M. Lipson, “Wide-bandwidth continuously tunable optical delay line using silicon microring resonators,” Opt. Express 18(25), 26525–26534 (2010). [CrossRef] [PubMed]

] but a smaller number of heaters to form a slope of the detuning. This is effective for simplifying the heater control and making the envelope spectrum smoother.

In this paper, we first summarize the theoretical background indicating the advantage of Si microrings, compared with other material systems. After describing the fabrication, we present the observation of fixed and tunable delays as well as the evaluation of the data transmission quality. We discuss the agreement with the theory, and advantages and issues of this approach.

2. Theory

So far, the single ring has been discussed. When the bus waveguide is coupled with isolated N rings having the same λ0 (Fig. 1(b)), T(λ) is given by multiplying Eq. (1) N times. Here, the second term in Eq. (1) is much smaller than unity in many cases. Therefore, T(λ) is approximated as
T(λ)1N(1A)(1T0)(1AT0)2+4AT0sin2(πneq/λ)
(9)
Under this condition, the total loss L, delay Δt, DBP and footprint S simply become N times larger, maintaining almost the same Δλ0. On the other hand, when rings have different λ0 due to the localized index change (Fig. 1(c)), the second term of Eq. (1) is replaced by the sum of all rings’ when the same approximation as for Eq. (9) is used, i.e.
T(λ)1i=1N(1A)(1T0)(1AT0)2+4AT0sin2(πneq(i)/λ)
(10)
In this case, Δλ of the envelope spectrum becomes larger than Δλ0, and L and Δt are reduced. Their minimum values will be the same as those for the single ring model when the spectra are completely split.

3. Fabrication

In the fabrication, CMOS-compatible process (8 inch SOI wafer, KrF stepper exposure) was used. Silica-clad Si wires of 0.40 μm width and 0.22 μm height are used for both bus waveguide and rings. For this waveguide, n g is calculated by using finite element method to be 4.2 at λ = 1.53 μm. The bus waveguide is terminated at input and output ends by inverse-taper-type fiber coupler, where the tip width of the Si inverse taper is 0.18 μm and the end waveguides are silica rectangular channels of (4 μm)2 cross-section. The coupling loss from lensed single mode fiber of 3 μm spot diameter to the bus waveguide is ~3.5 dB on each side (this loss can be reduced to 0.4 dB if the tip width is narrowed to 80 nm [14

14. T. Tsuchizawa, K. Yamada, H. Fukuda, T. Watanabe, S. Uchiyama, and S. Itabashi, “Low-loss Si wire waveguides and their application to thermooptic switches,” Jpn. J. Appl. Phys. 45(No. 8B), 6658–6662 (2006). [CrossRef]

]). The propagation loss is measured to be 3 − 5 dB/cm for the transverse-electric polarization at λ = 1.53 − 1.56 μm. The typical insertion loss from fiber to fiber through 2-mm-long Si wire is ~10 dB.

Figure 2
Fig. 2 Optical microscope images of fabricated device.
shows the optical micrograph of the fabricated device. Racetrack rings of 6 μm bend radius are coupled with the bus waveguide with a coupling length of 4.5 μm (ℓ = 46.7 μm). The free spectral range of the resonance is calculated from n g and ℓ to be 11.9 nm at λ = 1.53 μm. When the gap between the waveguide and ring, g, is 0.23 μm, T 0 is calculated to be 0.65 by using three-dimensional finite-difference time-domain simulation. The scattering loss at the coupling is also calculated to be 0.4%. Considering this value and an average waveguide loss of 4 dB/cm, α is estimated to be 1.84 cm−1, which ensures the above assumptions that A ~1 and the second term in Eq. (1) is much smaller than unity. Substituting these values into Eqs. (2)(4) gives Δλ0 = 0.84 nm, L = 0.35N [dB], Δt = 6.1N [ps] and DBP = 0.64N. Provided that the total insertion loss including the fiber coupling must be less than 30 dB so that the loss can be recovered by standard optical amplifier, N is set at 50, for which we calculate L = 17.4 dB, Δt = 305 ps and DBP = 32.

The space between adjacent rings is limited to 5 μm. Therefore, δ for this space and the racetrack shape is 0.3. The total device length p(1 + δ)N is 1060 μm, and the total footprint S = S 0 N only counting rings and the bus waveguide is as small as 0.014 mm2. From these values, Eqs. (4), (5), (7), (8) predict M = 46η [bits], L 0/M = 0.38/η [dB/bit], n geff = 95, FOM = 0.051, and M/S = 3.2η [kbit/mm2].

4. Measurement

Transmission and group delay spectra were measured by using dispersion analyzer Alnair FDA-2100 based on the modulation phase-shift method, where the delay in the Si wire without rings is used as a reference. Figure 3(a)
Fig. 3 Transmission and delay spectra. (a) Dependence on gap g without heating. Red, green and blue correspond to g = 0.19, 0.21 and 0.23 μm, respectively. (b) Change of delay spectrum with heating for g = 0.23 μm.
shows the results for three different g. The spectral dip and delay peak are very simple and smooth, which may be difficult to obtain in CROW. Such a dip and peak were observed periodically with a free spectral range of 11.9 nm at λ ~1.53 μm. It completely agrees with the aforementioned calculated value, which assures that other calculated values are also correct. The delay and loss at the resonance increase with increasing g. At g = 0.23 μm, the experimentally measured values are Δλ = 1.0 nm, L = 18 dB, Δt = 300 ps, DBP = 36, n geff = 85 and FOM = 0.056, all of which are in good agreement with theoretical values. This FOM is 4 − 5 fold smaller than typical values of 0.2 − 0.3 for photonic crystal devices. It is a reasonable result because the phase shift at the resonance of rings is smaller than that of photonic crystals under the slow light condition.

Next, we discuss the delay tuning, which is the major difference from Ref. [11

11. F. Xia, L. Sekaric, and Y. Vlasov, “Ultracompact optical buffers on a silicon chip,” Nat. Photonics 1(1), 65–71 (2007). [CrossRef]

]. reporting a large-scale integration of similar all-pass Si microrings. In the fabricated device, five TiN heaters were placed beside the rings with 200 μm pitch, as shown in Fig. 2. In addition, eight heaters were placed outside of the area of Fig. 2. Around the inner heaters and between inner and outer heaters, some trenches are perforated through the silica clad to the Si substrate to improve the heating efficiency and suppress the thermal crosstalk. Inner heaters, each of which is controlled independently, are used to form a temperature slope and tune the delay and bandwidth. As the dispersion analyzer can acquire one delay spectrum within a few seconds, we can form a desired envelope spectrum by repeating the measurement while controlling the inner heaters. However, overall the spectrum redshifts due to some thermal crosstalk when only using the inner heaters. Therefore, the outer heaters are also used to heat the device uniformly when the inner heaters are not used heavily, so that the spectral peak is always redshifted and located at the same wavelength. Figure 3(b) shows the change of the delay spectrum with heating. Here, the target wavelength is set at 3.5 nm longer than that without heating (near 1532 nm), which maximizes the tuning range, avoiding severe thermal crosstalk. Values in this figure denote the total heating power. Many of them have similar values, but the power balance between heaters is changed variously. The power values might be higher than normal for microrings, because the heating from the side is not so efficient. In this experiment, we could not form top heaters above the rings due to the restriction of multiple-project wafer process. If top heaters can be used, the power will be reduced significantly. At the target wavelength, the delay Δt is controlled in the range of 4 – 300 ps. At Δt ≥ 150 ps, Δt and the bandwidth are changed continuously while maintaining the peak wavelength. Αt Δt = 150 ps, a flat top spectrum of 1.3 nm width is obtained. At Δt < 150 ps, the heating power to the inner heaters increased and the thermal crosstalk became severer. Since the temperature slope was not sufficient under this condition, it was difficult to expand the bandwidth further at the same wavelength. Therefore, we simply blueshifted the peak wavelength by reducing the total power so that Δt decreases to 4 ps at its minimum.

To confirm the transmission quality of optical signals with delays, eye diagrams and serial bit patterns were observed for 40 Gbps non-return zero (NRZ) 27−1 pseudo-random bit sequence (PRBS), as shown in Fig. 4
Fig. 4 Eye diagram (a) and bit pattern (b) of 40 Gbps NRZ 27−1 PRBS signal output from the device. A-D correspond to those in Fig. 3.
. At Δt ≤ 150 ps, the eye opening is observed with the clear bit pattern, for which we can confirm the tunable buffering capacity of M = 4 bits, the buffering density M/S = 0.29 kbit/mm2, and the buffering loss L/M = 3.5 dB/bit. At Δt > 150 ps, the eye closes although the pattern can still be recognized. It might be affected by a dispersion larger than 10 ps/nm. It can be reduced by suppressing the thermal crosstalk and controlling the local temperature minutely. D exhibits a delay of 184 ps = 7.3 bit, which agrees with the result in Fig. 3(b) and is also consistent with the theoretical prediction that M ~9 bit and M/S ~0.64 kbit/mm2 at the maximum delay when we assume η ~0.2 approximated for the PRBS signals against the spectral response without heating in Fig. 3(a).

5. Discussion

In this study, we employed all-pass microrings for tunable delay, rather than photonic crystals and CROWs because of the ease of fabrication and the spectral robustness, respectively. As understood from Eqs. (4) and (9), the buffering capacity of each ring is constant for any design and material system, and the spatial buffering density is simply enhanced by downsizing each ring. For this purpose, the high-index-contrast Si wire waveguide can be an ideal platform. Since our device employed a very compact arrangement of rings and simpler bus waveguide, the footprint is as small as 0.014 mm2, which is much smaller than 0.09 mm2 for a similar device [11

11. F. Xia, L. Sekaric, and Y. Vlasov, “Ultracompact optical buffers on a silicon chip,” Nat. Photonics 1(1), 65–71 (2007). [CrossRef]

] and even smaller than 0.025 mm2 for a Si microring CROW [9

9. A. Melloni, A. Canciamilla, C. Ferrari, F. Morichetti, L. O'Faolain, T. F. Krauss, R. De La Rue, A. Samarelli, and M. Sorel, “Tunable delay lines in silicon photonics: coupled resonators and photonic crystals, a comparison,” IEEE Photon. J. 2(2), 181–194 (2010). [CrossRef]

]. Therefore, even comparing our tunable delay with the fixed delay in Ref. [11

11. F. Xia, L. Sekaric, and Y. Vlasov, “Ultracompact optical buffers on a silicon chip,” Nat. Photonics 1(1), 65–71 (2007). [CrossRef]

], our buffering density is 2.6 times larger. Of course, it is 2 − 3 orders higher than those in low-index-contrast systems [5

5. J. Yang, N. K. Fontaine, Z. Pan, A. O. Karalar, S. S. Djordjevic, C. Yang, W. Chen, S. Chu, B. E. Little, and S. J. B. Yoo, “Continuously tunable, wavelength-selective buffering in optical packet switching network,” IEEE Photon. Technol. Lett. 20(12), 1030–1032 (2008). [CrossRef]

,8

8. A. Melloni, F. Morichetti, C. Ferrari, and M. Martinelli, “Continuously tunable 1 byte delay in coupled-resonator optical waveguides,” Opt. Lett. 33(20), 2389–2391 (2008). [CrossRef] [PubMed]

]. The delay may be enhanced up to 1 ns with 200 microrings, for which the device footprint is still reasonably small (< 0.06 mm2). In a larger array, the fine control of local temperatures will be easier, so the dispersion will be more suppressed. The main issue is the reduction of loss. The buffering loss in this study is 3 – 5 times higher than those of low-index-contrast systems, and the total loss for a 1 ns delay cannot be recovered by optical amplifier. At the very least, the buffering loss will be reduced to a comparable level and the total loss will be acceptable by suppressing the scattering loss at the directional coupling by optimizing the design and by using the state-of-the-art Si photonics technology, which has already achieved a waveguide loss of 2 dB/cm [14

14. T. Tsuchizawa, K. Yamada, H. Fukuda, T. Watanabe, S. Uchiyama, and S. Itabashi, “Low-loss Si wire waveguides and their application to thermooptic switches,” Jpn. J. Appl. Phys. 45(No. 8B), 6658–6662 (2006). [CrossRef]

]. Further enhancement of the delay and capacity simply depends on a lower waveguide loss without losing the compactness of the ring. Other novel process is worth investigating for this purpose [15

15. J. Cardenas, C. B. Poitras, J. T. Robinson, K. Preston, L. Chen, and M. Lipson, “Low loss etchless silicon photonic waveguides,” Opt. Express 17(6), 4752–4757 (2009). [CrossRef] [PubMed]

].

Acknowledgments

This work was partly supported by The FIRST Program of the Japan Society for the Promotion of Science.

References and links

1.

R. S. Tucker, P.-C. Ku, and C. Chang-Hasnain, “Slow-light optical buffers - capabilities and fundamental limitations,” J. Lightwave Technol. 23(12), 4046–4066 (2005). [CrossRef]

2.

T. Baba, “Slow light in photonic crystals,” Nat. Photonics 2(8), 465–473 (2008). [CrossRef]

3.

T. Baba, T. Kawaaski, H. Sasaki, J. Adachi, and D. Mori, “Large delay-bandwidth product and tuning of slow light pulse in photonic crystal coupled waveguide,” Opt. Express 16(12), 9245–9253 (2008). [CrossRef] [PubMed]

4.

J. Adachi, N. Ishikura, H. Sasaki, and T. Baba, “Wide range tuning of slow light pulse in SOI photonic crystal coupled waveguide via folded chirping,” IEEE J. Sel. Top. Quantum Electron. 16(1), 192–199 (2010). [CrossRef]

5.

J. Yang, N. K. Fontaine, Z. Pan, A. O. Karalar, S. S. Djordjevic, C. Yang, W. Chen, S. Chu, B. E. Little, and S. J. B. Yoo, “Continuously tunable, wavelength-selective buffering in optical packet switching network,” IEEE Photon. Technol. Lett. 20(12), 1030–1032 (2008). [CrossRef]

6.

W. M. J. Green, H. F. Hamann, L. Sekaric, M. J. Rooks, and Y. A. Vlasov, “Ultra-compact reconfigurable silicon optical devices using micron-scale localized thermal heating,” Tech. Dig. Opt. Fiber Commun. Conf., OtuM3 (2007).

7.

J. Cardenas, M. A. Foster, N. Sherwood-Droz, C. B. Poitras, H. L. R. Lira, B. Zhang, A. L. Gaeta, J. B. Khurgin, P. Morton, and M. Lipson, “Wide-bandwidth continuously tunable optical delay line using silicon microring resonators,” Opt. Express 18(25), 26525–26534 (2010). [CrossRef] [PubMed]

8.

A. Melloni, F. Morichetti, C. Ferrari, and M. Martinelli, “Continuously tunable 1 byte delay in coupled-resonator optical waveguides,” Opt. Lett. 33(20), 2389–2391 (2008). [CrossRef] [PubMed]

9.

A. Melloni, A. Canciamilla, C. Ferrari, F. Morichetti, L. O'Faolain, T. F. Krauss, R. De La Rue, A. Samarelli, and M. Sorel, “Tunable delay lines in silicon photonics: coupled resonators and photonic crystals, a comparison,” IEEE Photon. J. 2(2), 181–194 (2010). [CrossRef]

10.

Q. Li, F. Liu, Z. Zhang, M. Qiu, and Y. Su, “System performances of on-chip silicon microring delay line for RZ, CSRZ, RZ-DB and RZ-AMI signals,” J. Lightwave Technol. 26(23), 3744–3751 (2008). [CrossRef]

11.

F. Xia, L. Sekaric, and Y. Vlasov, “Ultracompact optical buffers on a silicon chip,” Nat. Photonics 1(1), 65–71 (2007). [CrossRef]

12.

K. Okamoto, Fundamentals of Optical Waveguides, 2nd ed. (Academic Press, 2000).

13.

H. P. Uranus and H. J. W. M. Hoekstra, “Modeling of loss-induced superluminal and negative group velocity in two-port ring-resonator circuits,” J. Lightwave Technol. 25(9), 2376–2384 (2007). [CrossRef]

14.

T. Tsuchizawa, K. Yamada, H. Fukuda, T. Watanabe, S. Uchiyama, and S. Itabashi, “Low-loss Si wire waveguides and their application to thermooptic switches,” Jpn. J. Appl. Phys. 45(No. 8B), 6658–6662 (2006). [CrossRef]

15.

J. Cardenas, C. B. Poitras, J. T. Robinson, K. Preston, L. Chen, and M. Lipson, “Low loss etchless silicon photonic waveguides,” Opt. Express 17(6), 4752–4757 (2009). [CrossRef] [PubMed]

OCIS Codes
(230.3120) Optical devices : Integrated optics devices
(230.5750) Optical devices : Resonators

ToC Category:
Optical Devices

History
Original Manuscript: April 20, 2011
Revised Manuscript: June 10, 2011
Manuscript Accepted: June 17, 2011
Published: June 29, 2011

Citation
Fumihiro Shinobu, Norihiro Ishikura, Yoshiki Arita, Takemasa Tamanuki, and Toshihiko Baba, "Continuously tunable slow-light device consisting of heater-controlled silicon microring array," Opt. Express 19, 13557-13564 (2011)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-14-13557


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References

  1. R. S. Tucker, P.-C. Ku, and C. Chang-Hasnain, “Slow-light optical buffers - capabilities and fundamental limitations,” J. Lightwave Technol. 23(12), 4046–4066 (2005). [CrossRef]
  2. T. Baba, “Slow light in photonic crystals,” Nat. Photonics 2(8), 465–473 (2008). [CrossRef]
  3. T. Baba, T. Kawaaski, H. Sasaki, J. Adachi, and D. Mori, “Large delay-bandwidth product and tuning of slow light pulse in photonic crystal coupled waveguide,” Opt. Express 16(12), 9245–9253 (2008). [CrossRef] [PubMed]
  4. J. Adachi, N. Ishikura, H. Sasaki, and T. Baba, “Wide range tuning of slow light pulse in SOI photonic crystal coupled waveguide via folded chirping,” IEEE J. Sel. Top. Quantum Electron. 16(1), 192–199 (2010). [CrossRef]
  5. J. Yang, N. K. Fontaine, Z. Pan, A. O. Karalar, S. S. Djordjevic, C. Yang, W. Chen, S. Chu, B. E. Little, and S. J. B. Yoo, “Continuously tunable, wavelength-selective buffering in optical packet switching network,” IEEE Photon. Technol. Lett. 20(12), 1030–1032 (2008). [CrossRef]
  6. W. M. J. Green, H. F. Hamann, L. Sekaric, M. J. Rooks, and Y. A. Vlasov, “Ultra-compact reconfigurable silicon optical devices using micron-scale localized thermal heating,” Tech. Dig. Opt. Fiber Commun. Conf., OtuM3 (2007).
  7. J. Cardenas, M. A. Foster, N. Sherwood-Droz, C. B. Poitras, H. L. R. Lira, B. Zhang, A. L. Gaeta, J. B. Khurgin, P. Morton, and M. Lipson, “Wide-bandwidth continuously tunable optical delay line using silicon microring resonators,” Opt. Express 18(25), 26525–26534 (2010). [CrossRef] [PubMed]
  8. A. Melloni, F. Morichetti, C. Ferrari, and M. Martinelli, “Continuously tunable 1 byte delay in coupled-resonator optical waveguides,” Opt. Lett. 33(20), 2389–2391 (2008). [CrossRef] [PubMed]
  9. A. Melloni, A. Canciamilla, C. Ferrari, F. Morichetti, L. O'Faolain, T. F. Krauss, R. De La Rue, A. Samarelli, and M. Sorel, “Tunable delay lines in silicon photonics: coupled resonators and photonic crystals, a comparison,” IEEE Photon. J. 2(2), 181–194 (2010). [CrossRef]
  10. Q. Li, F. Liu, Z. Zhang, M. Qiu, and Y. Su, “System performances of on-chip silicon microring delay line for RZ, CSRZ, RZ-DB and RZ-AMI signals,” J. Lightwave Technol. 26(23), 3744–3751 (2008). [CrossRef]
  11. F. Xia, L. Sekaric, and Y. Vlasov, “Ultracompact optical buffers on a silicon chip,” Nat. Photonics 1(1), 65–71 (2007). [CrossRef]
  12. K. Okamoto, Fundamentals of Optical Waveguides, 2nd ed. (Academic Press, 2000).
  13. H. P. Uranus and H. J. W. M. Hoekstra, “Modeling of loss-induced superluminal and negative group velocity in two-port ring-resonator circuits,” J. Lightwave Technol. 25(9), 2376–2384 (2007). [CrossRef]
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