Abstract

Broad-band Mach-Zehnder interferometry is analytically described and experimentally demonstrated as an analytical tool capable of high accuracy refractive index measurements over a wide spectral range. Suitable photonic engineering of the interferometer sensing and reference waveguides result in sinusoidal TE and TM spectra with substantially different eigen-frequencies. This allows for the instantaneous deconvolution of multiplexed polarizations and enables large spectral shifts and noise reduction through filtering in the Fourier Transform domain. Due to enhanced sensitivity, optical systems can be designed that employ portable spectrum analyzers with nm range resolution without compromising the sensor analytical capability. Practical detection limits in the 10−6-10−7 RIU range are achievable, including temperature effects. Finally, a proof of concept device is realized on a silicon microphotonic chip that monolithically integrates broad-band light sources and single mode silicon nitride waveguides. Refractive index detection limits rivaling that of ring resonators with externally coupled laser sources are demonstrated. Sensitivities of 20 μm/RIU and spectral shifts in the tens of a pm are obtained.

© 2014 Optical Society of America

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References

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  1. C. Ciminelli, C. M. Campanella, F. Dell’Olio, C. E. Campanella, M. N. Armenise, “Label-free optical resonant sensors for biochemical applications,” Prog. Quantum Electron. 37(2), 51–107 (2013).
    [CrossRef]
  2. I. M. White, X. Fan, “On the performance quantification of resonant refractive index sensors,” Opt. Express 16(2), 1020–1028 (2008).
    [CrossRef] [PubMed]
  3. X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, Y. Sun, “Sensitive optical biosensors for unlabeled targets: A review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
    [CrossRef] [PubMed]
  4. M. La Notte, V. M. N. Passaro, “Ultra high sensitivity chemical photonic sensing by Mach–Zehnder interferometer enhanced Vernier-effect,” Sens. Actuat. B 176, 994–1007 (2013).
    [CrossRef]
  5. N. A. Yebo, S. P. Sree, E. Levrau, C. Detavernier, Z. Hens, J. A. Martens, R. Baets, “Selective and reversible ammonia gas detection with nanoporous film functionalized silicon photonic micro-ring resonator,” Opt. Express 20(11), 11855–11862 (2012).
    [CrossRef] [PubMed]
  6. M. Kitsara, K. Misiakos, I. Raptis, E. Makarona, “Integrated optical frequency-resolved Mach-Zehnder interferometers for label-free affinity sensing,” Opt. Express 18(8), 8193–8206 (2010).
    [CrossRef] [PubMed]
  7. R. G. Heideman, P. V. Lambeck, “Remote opto-chemical sensing with extreme sensitivity: design,fabrication and performance of a pigtailed integrated optical phase-modulated Mach–Zehnder interferometer system,” Sens. Actuat. B 61(1-3), 100–127 (1999).
    [CrossRef]
  8. S. Dante, D. Duval, B. Sepúlveda, A. B. González-Guerrero, J. R. Sendra, L. M. Lechuga, “All-optical phase modulation for integrated interferometric biosensors,” Opt. Express 20(7), 7195–7205 (2012).
    [CrossRef] [PubMed]
  9. A. Chynoweth, K. Mckay, “Photon emission from avalanche breakdown in silicon,” Phys. Rev. 102(2), 369–376 (1956).
    [CrossRef]
  10. K. Misiakos, S. E. Kakabakos, P. S. Petrou, H. H. Ruf, “A Monolithic silicon optoelectronic transducer as a real-time affinity biosensor,” Anal. Chem. 76(5), 1366–1373 (2004).
    [CrossRef] [PubMed]
  11. E. Mavrogiannopoulou, P. S. Petrou, S. E. Kakabakos, K. Misiakos, “Real-time detection of BRCA1 gene mutations using a monolithic silicon optocoupler array,” Biosens. Bioelectron. 24(5), 1341–1347 (2009).
    [CrossRef] [PubMed]
  12. K. Misiakos, I. Raptis, A. Gerardino, H. Contopanagos, M. Kitsara, “A monolithic photonic microcantilever device for in situ monitoring of volatile compounds,” Lab Chip 9(9), 1261–1266 (2009).
    [CrossRef] [PubMed]
  13. Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
    [CrossRef]

2013 (3)

C. Ciminelli, C. M. Campanella, F. Dell’Olio, C. E. Campanella, M. N. Armenise, “Label-free optical resonant sensors for biochemical applications,” Prog. Quantum Electron. 37(2), 51–107 (2013).
[CrossRef]

M. La Notte, V. M. N. Passaro, “Ultra high sensitivity chemical photonic sensing by Mach–Zehnder interferometer enhanced Vernier-effect,” Sens. Actuat. B 176, 994–1007 (2013).
[CrossRef]

Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
[CrossRef]

2012 (2)

2010 (1)

2009 (2)

E. Mavrogiannopoulou, P. S. Petrou, S. E. Kakabakos, K. Misiakos, “Real-time detection of BRCA1 gene mutations using a monolithic silicon optocoupler array,” Biosens. Bioelectron. 24(5), 1341–1347 (2009).
[CrossRef] [PubMed]

K. Misiakos, I. Raptis, A. Gerardino, H. Contopanagos, M. Kitsara, “A monolithic photonic microcantilever device for in situ monitoring of volatile compounds,” Lab Chip 9(9), 1261–1266 (2009).
[CrossRef] [PubMed]

2008 (2)

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, Y. Sun, “Sensitive optical biosensors for unlabeled targets: A review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

I. M. White, X. Fan, “On the performance quantification of resonant refractive index sensors,” Opt. Express 16(2), 1020–1028 (2008).
[CrossRef] [PubMed]

2004 (1)

K. Misiakos, S. E. Kakabakos, P. S. Petrou, H. H. Ruf, “A Monolithic silicon optoelectronic transducer as a real-time affinity biosensor,” Anal. Chem. 76(5), 1366–1373 (2004).
[CrossRef] [PubMed]

1999 (1)

R. G. Heideman, P. V. Lambeck, “Remote opto-chemical sensing with extreme sensitivity: design,fabrication and performance of a pigtailed integrated optical phase-modulated Mach–Zehnder interferometer system,” Sens. Actuat. B 61(1-3), 100–127 (1999).
[CrossRef]

1956 (1)

A. Chynoweth, K. Mckay, “Photon emission from avalanche breakdown in silicon,” Phys. Rev. 102(2), 369–376 (1956).
[CrossRef]

Armenise, M. N.

C. Ciminelli, C. M. Campanella, F. Dell’Olio, C. E. Campanella, M. N. Armenise, “Label-free optical resonant sensors for biochemical applications,” Prog. Quantum Electron. 37(2), 51–107 (2013).
[CrossRef]

Baets, R.

Campanella, C. E.

C. Ciminelli, C. M. Campanella, F. Dell’Olio, C. E. Campanella, M. N. Armenise, “Label-free optical resonant sensors for biochemical applications,” Prog. Quantum Electron. 37(2), 51–107 (2013).
[CrossRef]

Campanella, C. M.

C. Ciminelli, C. M. Campanella, F. Dell’Olio, C. E. Campanella, M. N. Armenise, “Label-free optical resonant sensors for biochemical applications,” Prog. Quantum Electron. 37(2), 51–107 (2013).
[CrossRef]

Chynoweth, A.

A. Chynoweth, K. Mckay, “Photon emission from avalanche breakdown in silicon,” Phys. Rev. 102(2), 369–376 (1956).
[CrossRef]

Ciminelli, C.

C. Ciminelli, C. M. Campanella, F. Dell’Olio, C. E. Campanella, M. N. Armenise, “Label-free optical resonant sensors for biochemical applications,” Prog. Quantum Electron. 37(2), 51–107 (2013).
[CrossRef]

Contopanagos, H.

K. Misiakos, I. Raptis, A. Gerardino, H. Contopanagos, M. Kitsara, “A monolithic photonic microcantilever device for in situ monitoring of volatile compounds,” Lab Chip 9(9), 1261–1266 (2009).
[CrossRef] [PubMed]

Dante, S.

Dell’Olio, F.

C. Ciminelli, C. M. Campanella, F. Dell’Olio, C. E. Campanella, M. N. Armenise, “Label-free optical resonant sensors for biochemical applications,” Prog. Quantum Electron. 37(2), 51–107 (2013).
[CrossRef]

Detavernier, C.

Duval, D.

Fan, X.

I. M. White, X. Fan, “On the performance quantification of resonant refractive index sensors,” Opt. Express 16(2), 1020–1028 (2008).
[CrossRef] [PubMed]

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, Y. Sun, “Sensitive optical biosensors for unlabeled targets: A review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Gerardino, A.

K. Misiakos, I. Raptis, A. Gerardino, H. Contopanagos, M. Kitsara, “A monolithic photonic microcantilever device for in situ monitoring of volatile compounds,” Lab Chip 9(9), 1261–1266 (2009).
[CrossRef] [PubMed]

González-Guerrero, A. B.

Han, K.

Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
[CrossRef]

Heideman, R. G.

R. G. Heideman, P. V. Lambeck, “Remote opto-chemical sensing with extreme sensitivity: design,fabrication and performance of a pigtailed integrated optical phase-modulated Mach–Zehnder interferometer system,” Sens. Actuat. B 61(1-3), 100–127 (1999).
[CrossRef]

Hens, Z.

Kakabakos, S. E.

E. Mavrogiannopoulou, P. S. Petrou, S. E. Kakabakos, K. Misiakos, “Real-time detection of BRCA1 gene mutations using a monolithic silicon optocoupler array,” Biosens. Bioelectron. 24(5), 1341–1347 (2009).
[CrossRef] [PubMed]

K. Misiakos, S. E. Kakabakos, P. S. Petrou, H. H. Ruf, “A Monolithic silicon optoelectronic transducer as a real-time affinity biosensor,” Anal. Chem. 76(5), 1366–1373 (2004).
[CrossRef] [PubMed]

Kee, J. S.

Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
[CrossRef]

Kim, K. W.

Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
[CrossRef]

Kitsara, M.

M. Kitsara, K. Misiakos, I. Raptis, E. Makarona, “Integrated optical frequency-resolved Mach-Zehnder interferometers for label-free affinity sensing,” Opt. Express 18(8), 8193–8206 (2010).
[CrossRef] [PubMed]

K. Misiakos, I. Raptis, A. Gerardino, H. Contopanagos, M. Kitsara, “A monolithic photonic microcantilever device for in situ monitoring of volatile compounds,” Lab Chip 9(9), 1261–1266 (2009).
[CrossRef] [PubMed]

La Notte, M.

M. La Notte, V. M. N. Passaro, “Ultra high sensitivity chemical photonic sensing by Mach–Zehnder interferometer enhanced Vernier-effect,” Sens. Actuat. B 176, 994–1007 (2013).
[CrossRef]

Lambeck, P. V.

R. G. Heideman, P. V. Lambeck, “Remote opto-chemical sensing with extreme sensitivity: design,fabrication and performance of a pigtailed integrated optical phase-modulated Mach–Zehnder interferometer system,” Sens. Actuat. B 61(1-3), 100–127 (1999).
[CrossRef]

Lechuga, L. M.

Levrau, E.

Liu, Q.

Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
[CrossRef]

Lo, G. Q.

Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
[CrossRef]

Makarona, E.

Martens, J. A.

Mavrogiannopoulou, E.

E. Mavrogiannopoulou, P. S. Petrou, S. E. Kakabakos, K. Misiakos, “Real-time detection of BRCA1 gene mutations using a monolithic silicon optocoupler array,” Biosens. Bioelectron. 24(5), 1341–1347 (2009).
[CrossRef] [PubMed]

Mckay, K.

A. Chynoweth, K. Mckay, “Photon emission from avalanche breakdown in silicon,” Phys. Rev. 102(2), 369–376 (1956).
[CrossRef]

Misiakos, K.

M. Kitsara, K. Misiakos, I. Raptis, E. Makarona, “Integrated optical frequency-resolved Mach-Zehnder interferometers for label-free affinity sensing,” Opt. Express 18(8), 8193–8206 (2010).
[CrossRef] [PubMed]

E. Mavrogiannopoulou, P. S. Petrou, S. E. Kakabakos, K. Misiakos, “Real-time detection of BRCA1 gene mutations using a monolithic silicon optocoupler array,” Biosens. Bioelectron. 24(5), 1341–1347 (2009).
[CrossRef] [PubMed]

K. Misiakos, I. Raptis, A. Gerardino, H. Contopanagos, M. Kitsara, “A monolithic photonic microcantilever device for in situ monitoring of volatile compounds,” Lab Chip 9(9), 1261–1266 (2009).
[CrossRef] [PubMed]

K. Misiakos, S. E. Kakabakos, P. S. Petrou, H. H. Ruf, “A Monolithic silicon optoelectronic transducer as a real-time affinity biosensor,” Anal. Chem. 76(5), 1366–1373 (2004).
[CrossRef] [PubMed]

Park, M. K.

Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
[CrossRef]

Passaro, V. M. N.

M. La Notte, V. M. N. Passaro, “Ultra high sensitivity chemical photonic sensing by Mach–Zehnder interferometer enhanced Vernier-effect,” Sens. Actuat. B 176, 994–1007 (2013).
[CrossRef]

Petrou, P. S.

E. Mavrogiannopoulou, P. S. Petrou, S. E. Kakabakos, K. Misiakos, “Real-time detection of BRCA1 gene mutations using a monolithic silicon optocoupler array,” Biosens. Bioelectron. 24(5), 1341–1347 (2009).
[CrossRef] [PubMed]

K. Misiakos, S. E. Kakabakos, P. S. Petrou, H. H. Ruf, “A Monolithic silicon optoelectronic transducer as a real-time affinity biosensor,” Anal. Chem. 76(5), 1366–1373 (2004).
[CrossRef] [PubMed]

Raptis, I.

M. Kitsara, K. Misiakos, I. Raptis, E. Makarona, “Integrated optical frequency-resolved Mach-Zehnder interferometers for label-free affinity sensing,” Opt. Express 18(8), 8193–8206 (2010).
[CrossRef] [PubMed]

K. Misiakos, I. Raptis, A. Gerardino, H. Contopanagos, M. Kitsara, “A monolithic photonic microcantilever device for in situ monitoring of volatile compounds,” Lab Chip 9(9), 1261–1266 (2009).
[CrossRef] [PubMed]

Ruf, H. H.

K. Misiakos, S. E. Kakabakos, P. S. Petrou, H. H. Ruf, “A Monolithic silicon optoelectronic transducer as a real-time affinity biosensor,” Anal. Chem. 76(5), 1366–1373 (2004).
[CrossRef] [PubMed]

Sendra, J. R.

Sepúlveda, B.

Shin, Y.

Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
[CrossRef]

Shopova, S. I.

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, Y. Sun, “Sensitive optical biosensors for unlabeled targets: A review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Sree, S. P.

Sun, Y.

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, Y. Sun, “Sensitive optical biosensors for unlabeled targets: A review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Suter, J. D.

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, Y. Sun, “Sensitive optical biosensors for unlabeled targets: A review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Tu, X.

Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
[CrossRef]

White, I. M.

I. M. White, X. Fan, “On the performance quantification of resonant refractive index sensors,” Opt. Express 16(2), 1020–1028 (2008).
[CrossRef] [PubMed]

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, Y. Sun, “Sensitive optical biosensors for unlabeled targets: A review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Yebo, N. A.

Yoon, Y. J.

Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
[CrossRef]

Zhu, H.

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, Y. Sun, “Sensitive optical biosensors for unlabeled targets: A review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Anal. Chem. (1)

K. Misiakos, S. E. Kakabakos, P. S. Petrou, H. H. Ruf, “A Monolithic silicon optoelectronic transducer as a real-time affinity biosensor,” Anal. Chem. 76(5), 1366–1373 (2004).
[CrossRef] [PubMed]

Anal. Chim. Acta (1)

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, Y. Sun, “Sensitive optical biosensors for unlabeled targets: A review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Biosens. Bioelectron. (1)

E. Mavrogiannopoulou, P. S. Petrou, S. E. Kakabakos, K. Misiakos, “Real-time detection of BRCA1 gene mutations using a monolithic silicon optocoupler array,” Biosens. Bioelectron. 24(5), 1341–1347 (2009).
[CrossRef] [PubMed]

Lab Chip (1)

K. Misiakos, I. Raptis, A. Gerardino, H. Contopanagos, M. Kitsara, “A monolithic photonic microcantilever device for in situ monitoring of volatile compounds,” Lab Chip 9(9), 1261–1266 (2009).
[CrossRef] [PubMed]

Opt. Express (4)

Phys. Rev. (1)

A. Chynoweth, K. Mckay, “Photon emission from avalanche breakdown in silicon,” Phys. Rev. 102(2), 369–376 (1956).
[CrossRef]

Prog. Quantum Electron. (1)

C. Ciminelli, C. M. Campanella, F. Dell’Olio, C. E. Campanella, M. N. Armenise, “Label-free optical resonant sensors for biochemical applications,” Prog. Quantum Electron. 37(2), 51–107 (2013).
[CrossRef]

Sens Actuat. B (1)

Q. Liu, X. Tu, K. W. Kim, J. S. Kee, Y. Shin, K. Han, Y. J. Yoon, G. Q. Lo, M. K. Park, “Highly sensitive Mach–Zehnder interferometer biosensor based on silicon nitride slot waveguide,” Sens Actuat. B 188, 681–688 (2013).
[CrossRef]

Sens. Actuat. B (2)

R. G. Heideman, P. V. Lambeck, “Remote opto-chemical sensing with extreme sensitivity: design,fabrication and performance of a pigtailed integrated optical phase-modulated Mach–Zehnder interferometer system,” Sens. Actuat. B 61(1-3), 100–127 (1999).
[CrossRef]

M. La Notte, V. M. N. Passaro, “Ultra high sensitivity chemical photonic sensing by Mach–Zehnder interferometer enhanced Vernier-effect,” Sens. Actuat. B 176, 994–1007 (2013).
[CrossRef]

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Figures (8)

Fig. 1
Fig. 1

A Mach-Zehnder interferometer with a broad-band input and an output modulated according to Eq. (4). The green lines are monomodal waveguides. The sensing arm exposed to the cover medium has a length L. Pink indicates the overcladding area.

Fig. 2
Fig. 2

Simulated propagation constant difference, cover medium effects and output spectra for the two polarizations for a MZ interferometer with L = 600μm and geometrical characteristics as described in the main text. In (a) and (b) the ratio ΔNrs is shown for nc = 1.33 (black) and nc = 1.34 (red) for the TE (a) and TM (b) polarization. The fundamental mode effective indices Nr, Ns were obtained through simulations with FemSIM software package (SYNOPSYS). The chromatic dispersions of the nitride core and oxide claddings were accounted for through independent spectroscopic ellipsometry measurements in separate nitride and oxide thin films deposited on silicon. The vertical shifts with increasing nc in (a) and (b) define the δΝs ratio in Eq. (11). The decreasing propagation constant difference with λ results in blue spectral shifts when the cover medium refractive index goes from 1.33 (black) to 1.34 (red) as shown in (c) and (d) for TE and TM. The TE shift is about a period while the TM shift is 2.4 periods.

Fig. 3
Fig. 3

Monolithic integration and basic optical configurations of the optocoupler device. (a). Schematic showing the LED, 1, the MZ interferometer, 2, and the silicon nitride rib waveguide, 3. Also shown is the waveguide bending over the SiO2 spacer, 4. The top cladding layer is removed over the sensing arm to expose it to the analyte (b). Photonic pathway and mode filtering. The waveguide starts as a 2μm wide multimode strip waveguide and then connects to the mode filter that rejects higher order modes and keeps the fundamental within the following shallow etched rib waveguide. The single mode rib waveguide is 1.25 μm wide and etched up to 4 nm. The mode filter consists of two back to back tapers: from 2-to-8 μm (strip) and 8-to-1.25 (rib). (c). Recorded spectra of the waveguided TE and TM modes at the emitting edge. (d) The LED and the emitting junction (white arrow) coupled to the multimode strip waveguide heading down. (e). The rib waveguide schematic. (f). The emitting edge of the single mode waveguide. Through a polarizer, the TE modes are shown along with the core width, 1.25μm, and the undercladding and overcladding thicknesses, S1 = 3 μm and S2 = 2μm. The slab between the overcladding and the undercladding is the nitride core.

Fig. 4
Fig. 4

Total signal monitoring and polarization separation through signal splitting in the DFT domain for a MZ with L = 600μm. The spectrometer employed was Maya Pro 2000, Ocean Optics. The LEDs are driven by a current source at 10 mA. (a). Total spectral response (TE + TM). Two frequencies are apparent. (b). DFT analysis of (a) showing the two distinct regions, TE and TM. The wavenumber is multiplied by the spectrometer spectral bandwidth (200-1100 nm) to express the peaks in DFT integers. (c). TE spectra as obtained with a polarizer and as obtained from signal splitting in the DFT domain. (d). TM spectra as obtained with a polarizer and as obtained from signal splitting in the DFT domain.

Fig. 5
Fig. 5

Phase responses for TE and TM for a cover medium transition of 1.2x10−2 RIU. The transition starts at 100s and ends in 450s. The results are obtained by processing the real time spectral measurements. The plot in (a) presents the TE and simultaneous TM responses obtained by polarization deconvolution through signal splitting in the DFT domain and peak argument tracking. The plot in (b) presents the TE and separate TM responses as phase shifts monitored separately by employing a polarizer and two successive measurements.

Fig. 6
Fig. 6

Spectral responses for the TE (a) and TM (b) polarization for water (black line) and water-2.5% isopropanol solution (red line). Here, δnc = 1.810−3 RIU and L = 2mm. The blue shifts in TE is nearly 34 nm (about 60% of a period) while in TM is 14 nm (about one and a half period). In (a) the shot signal noise is evident in the spectrum peaks as opposed to the valleys.

Fig. 7
Fig. 7

Calibration curve as phase shift per dilution ratio for L = 2mm. The highest dilution ratio (1/20000) corresponds to RI change of 3.610−6 RIU.

Fig. 8
Fig. 8

Phase response in the case of isopropanol dilution 1/20.000. The in arrow indicates the transition water to isopropanol solution and the out arrow the reverse transition.

Tables (1)

Tables Icon

Table 1 Root mean square values of the various noise sources and detection limits for the two polarizations and two values of L. The spectrometer has a 16 bit vertical resolution and a thousand channels in the spectral region of interest.

Equations (32)

Equations on this page are rendered with MathJax. Learn more.

δλ= λ r δ N s ( λ r ) N gs ( λ r ) = δ N s ( λ r ) λ r ( N s /λ) λ
N gs = N s λ N s λ = λ 2 ( N s /λ) λ
δ λ = δ N s ( λ ) λ [ ( N s / λ ) λ + ( N r / λ ) λ ] = δ N s ( λ ) λ ( Δ N r s / λ ) λ
Τ ( λ ) = I o u t I i n = 1 2 [ 1 + cos ( ϕ ( λ ) ) ] = 1 2 [ 1 + cos ( 2 π Δ N r s λ L ) ] = 1 2 [ 1 + cos ( Δ K r s L ) ]
Δ K rs = K r K s = 2 π N r ( λ ) λ 2 π N s ( λ ) λ = 2 π Δ N rs ( λ ) λ
Δ K rs (λ)=2πΔ N rs (λ)/λ=2π(aλ+b) 
Τ(λ)=(1/2) [1+cos(2π(aλ+b)L)]
Δ Ν rs ( λ m )L/ λ m =m  
a= 1 L( λ m λ m1 ) , b= 1 L [ m λ m λ m λ m1 ]
T(λδλ)= 1 2 [1+cos(Δ K rs δ K s )L]= 1 2 [1+cos(2π{aλ+b δ N s λ }L)]=T(λ δ N s aλ )  
δλ= δ N s aλ = ( N s /λ) n c δ n c a =( λ m λ m1 )L( δ N s λ )
δ φ p =Lδ( K s )=L K s n c δ n c =2πL δ N s λ
s( λ i )= A 2 [1+cos(2π(a λ i +b)L)]
S(k)= i s( λ i )exp(j λ i k) = S R (k)+j S J (k)
N(k)= i n( λ i )exp(j λ i k) = N R (k)+j N J (k)
φ k 0 =arctan S J ( k 0 )+ N J ( k 0 ) S R ( k 0 )+ N R ( k 0 ) S J ( k 0 ) S R ( k 0 ) + N J ( k 0 ) S R ( k 0 ) S J ( k 0 ) S R ( k 0 ) 2 N R ( k 0 )
φ k 0 N J ( k 0 ) S R ( k 0 )
σ φ k 0 =σ φ sn = σ N J ( k 0 ) S R ( k 0 )
σ N 2 J ( k 0 )= i σ n 2 ( λ i ) sin 2 ( λ i k 0 )
σ n 2 ( λ i )=s( λ i )
σ N 2 J ( k 0 )= i s( λ i ) sin 2 ( λ i k 0 ) = i A 2 [1+cos(2π λ i k 0 )] sin 2 ( λ i k 0 ) = 1 4 AM 
σ φ sn = 2 AM
σ φ sn = 2 δM AW
DL=R/S
S φ = δ φ p δ n c =L δ K s δ n c =2πL (δ N s /λ) δ n c  
       DL= φ n S φ  = φ n 2πL[(δ N s /λ)/δ n c ]
       D L i = φ s n S φ  = 3 πL[(δ N s /λ)/δ n c )] AM
σ λ n = σ φ n L a   = σ φ n   ( λ m λ m 1 )    
σ φ t = 2 π L σ λ t ( N s / λ ) λ
S nTE = ( δ N s T E / λ ) / Δ n c = 1 . 65x1 0 4 ( nm ) 1 /RIU
S nTM = ( δ N s T M / λ ) / Δ n c = 3 . 8x1 0 4 ( nm ) 1 / RIU
              D L t = φ t S   = λ t ( N s / λ ) / λ [ δ N s / λ ] / δ n c

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