Abstract

We present direct UV-written waveguides and Bragg gratings operating at 780 nm. By combining two gratings into a Fabry-Perot cavity we have devised and implemented a novel and practical method of measuring the group delay of Bragg gratings.

© 2011 OSA

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References

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  1. I. J. G. Sparrow, G. D. Emmerson, C. B. E. Gawith, and P. G. R. Smith, “Planar waveguide hygrometer and state sensor demonstrating supercooled water recognition,” Sens. Actuators B 107, 856–860 (2005).
    [CrossRef]
  2. G. M. Hale and M. R. Querry, “Optical constants of water in the 200-nm to 200-μm wavelength region,” Appl. Opt. 12, 555–563 (1973).
    [CrossRef] [PubMed]
  3. G. Lepert, M. Trupke, M. J. Hartman, M. B. Plenio, and E. A. Hinds, “Arrays of waveguide-coupled optical cavities that interact strongly with atoms,” New J. Phys. 13, 113002 (2011).
    [CrossRef]
  4. M. Svalgaard, C. V. Poulsen, A. Bjarklev, and O. Poulsen, “Direct UV writing of buried single-mode channel waveguides in Ge-doped silica films,” Electron. Lett 30, 1401–1403 (1994).
    [CrossRef]
  5. D. O. Kundys, J. C. Gates, S. Dasgupta, C. Gawith, and P. Smith, “Use of cross-couplers to decrease size of UV written photonic circuits,” IEEE Photon. Technol. Lett. 21, 947–949 (2009).
    [CrossRef]
  6. T. Erdogan, “Fiber grating spectra,” J. Lightwave Technol. 15, 1277–1294 (1997).
    [CrossRef]
  7. Y. O. Barmenkov, D. Zalvidea, S. Torres-Peiró, J. L. Cruz, and M. V. Andrés, “Effective length of short Fabry-Perot cavity formed by uniform fiber Bragg gratings,” Opt. Express 14, 6394–6399 (2006).
    [CrossRef] [PubMed]
  8. M. Born and E. Wolf, Principles of Optics (Cambridge University Press, 1999)
  9. H. L. Rogers, S. Ambran, C. Holmes, P. G. R. Smith, and J. C. Gates, “In situ loss measurement of direct UV-written waveguides using integrated Bragg gratings,” Opt. Lett. 35, 2849–2851 (2010).
    [CrossRef] [PubMed]

2011 (1)

G. Lepert, M. Trupke, M. J. Hartman, M. B. Plenio, and E. A. Hinds, “Arrays of waveguide-coupled optical cavities that interact strongly with atoms,” New J. Phys. 13, 113002 (2011).
[CrossRef]

2010 (1)

2009 (1)

D. O. Kundys, J. C. Gates, S. Dasgupta, C. Gawith, and P. Smith, “Use of cross-couplers to decrease size of UV written photonic circuits,” IEEE Photon. Technol. Lett. 21, 947–949 (2009).
[CrossRef]

2006 (1)

2005 (1)

I. J. G. Sparrow, G. D. Emmerson, C. B. E. Gawith, and P. G. R. Smith, “Planar waveguide hygrometer and state sensor demonstrating supercooled water recognition,” Sens. Actuators B 107, 856–860 (2005).
[CrossRef]

1997 (1)

T. Erdogan, “Fiber grating spectra,” J. Lightwave Technol. 15, 1277–1294 (1997).
[CrossRef]

1994 (1)

M. Svalgaard, C. V. Poulsen, A. Bjarklev, and O. Poulsen, “Direct UV writing of buried single-mode channel waveguides in Ge-doped silica films,” Electron. Lett 30, 1401–1403 (1994).
[CrossRef]

1973 (1)

Ambran, S.

Andrés, M. V.

Barmenkov, Y. O.

Bjarklev, A.

M. Svalgaard, C. V. Poulsen, A. Bjarklev, and O. Poulsen, “Direct UV writing of buried single-mode channel waveguides in Ge-doped silica films,” Electron. Lett 30, 1401–1403 (1994).
[CrossRef]

Born, M.

M. Born and E. Wolf, Principles of Optics (Cambridge University Press, 1999)

Cruz, J. L.

Dasgupta, S.

D. O. Kundys, J. C. Gates, S. Dasgupta, C. Gawith, and P. Smith, “Use of cross-couplers to decrease size of UV written photonic circuits,” IEEE Photon. Technol. Lett. 21, 947–949 (2009).
[CrossRef]

Emmerson, G. D.

I. J. G. Sparrow, G. D. Emmerson, C. B. E. Gawith, and P. G. R. Smith, “Planar waveguide hygrometer and state sensor demonstrating supercooled water recognition,” Sens. Actuators B 107, 856–860 (2005).
[CrossRef]

Erdogan, T.

T. Erdogan, “Fiber grating spectra,” J. Lightwave Technol. 15, 1277–1294 (1997).
[CrossRef]

Gates, J. C.

H. L. Rogers, S. Ambran, C. Holmes, P. G. R. Smith, and J. C. Gates, “In situ loss measurement of direct UV-written waveguides using integrated Bragg gratings,” Opt. Lett. 35, 2849–2851 (2010).
[CrossRef] [PubMed]

D. O. Kundys, J. C. Gates, S. Dasgupta, C. Gawith, and P. Smith, “Use of cross-couplers to decrease size of UV written photonic circuits,” IEEE Photon. Technol. Lett. 21, 947–949 (2009).
[CrossRef]

Gawith, C.

D. O. Kundys, J. C. Gates, S. Dasgupta, C. Gawith, and P. Smith, “Use of cross-couplers to decrease size of UV written photonic circuits,” IEEE Photon. Technol. Lett. 21, 947–949 (2009).
[CrossRef]

Gawith, C. B. E.

I. J. G. Sparrow, G. D. Emmerson, C. B. E. Gawith, and P. G. R. Smith, “Planar waveguide hygrometer and state sensor demonstrating supercooled water recognition,” Sens. Actuators B 107, 856–860 (2005).
[CrossRef]

Hale, G. M.

Hartman, M. J.

G. Lepert, M. Trupke, M. J. Hartman, M. B. Plenio, and E. A. Hinds, “Arrays of waveguide-coupled optical cavities that interact strongly with atoms,” New J. Phys. 13, 113002 (2011).
[CrossRef]

Hinds, E. A.

G. Lepert, M. Trupke, M. J. Hartman, M. B. Plenio, and E. A. Hinds, “Arrays of waveguide-coupled optical cavities that interact strongly with atoms,” New J. Phys. 13, 113002 (2011).
[CrossRef]

Holmes, C.

Kundys, D. O.

D. O. Kundys, J. C. Gates, S. Dasgupta, C. Gawith, and P. Smith, “Use of cross-couplers to decrease size of UV written photonic circuits,” IEEE Photon. Technol. Lett. 21, 947–949 (2009).
[CrossRef]

Lepert, G.

G. Lepert, M. Trupke, M. J. Hartman, M. B. Plenio, and E. A. Hinds, “Arrays of waveguide-coupled optical cavities that interact strongly with atoms,” New J. Phys. 13, 113002 (2011).
[CrossRef]

Plenio, M. B.

G. Lepert, M. Trupke, M. J. Hartman, M. B. Plenio, and E. A. Hinds, “Arrays of waveguide-coupled optical cavities that interact strongly with atoms,” New J. Phys. 13, 113002 (2011).
[CrossRef]

Poulsen, C. V.

M. Svalgaard, C. V. Poulsen, A. Bjarklev, and O. Poulsen, “Direct UV writing of buried single-mode channel waveguides in Ge-doped silica films,” Electron. Lett 30, 1401–1403 (1994).
[CrossRef]

Poulsen, O.

M. Svalgaard, C. V. Poulsen, A. Bjarklev, and O. Poulsen, “Direct UV writing of buried single-mode channel waveguides in Ge-doped silica films,” Electron. Lett 30, 1401–1403 (1994).
[CrossRef]

Querry, M. R.

Rogers, H. L.

Smith, P.

D. O. Kundys, J. C. Gates, S. Dasgupta, C. Gawith, and P. Smith, “Use of cross-couplers to decrease size of UV written photonic circuits,” IEEE Photon. Technol. Lett. 21, 947–949 (2009).
[CrossRef]

Smith, P. G. R.

H. L. Rogers, S. Ambran, C. Holmes, P. G. R. Smith, and J. C. Gates, “In situ loss measurement of direct UV-written waveguides using integrated Bragg gratings,” Opt. Lett. 35, 2849–2851 (2010).
[CrossRef] [PubMed]

I. J. G. Sparrow, G. D. Emmerson, C. B. E. Gawith, and P. G. R. Smith, “Planar waveguide hygrometer and state sensor demonstrating supercooled water recognition,” Sens. Actuators B 107, 856–860 (2005).
[CrossRef]

Sparrow, I. J. G.

I. J. G. Sparrow, G. D. Emmerson, C. B. E. Gawith, and P. G. R. Smith, “Planar waveguide hygrometer and state sensor demonstrating supercooled water recognition,” Sens. Actuators B 107, 856–860 (2005).
[CrossRef]

Svalgaard, M.

M. Svalgaard, C. V. Poulsen, A. Bjarklev, and O. Poulsen, “Direct UV writing of buried single-mode channel waveguides in Ge-doped silica films,” Electron. Lett 30, 1401–1403 (1994).
[CrossRef]

Torres-Peiró, S.

Trupke, M.

G. Lepert, M. Trupke, M. J. Hartman, M. B. Plenio, and E. A. Hinds, “Arrays of waveguide-coupled optical cavities that interact strongly with atoms,” New J. Phys. 13, 113002 (2011).
[CrossRef]

Wolf, E.

M. Born and E. Wolf, Principles of Optics (Cambridge University Press, 1999)

Zalvidea, D.

Appl. Opt. (1)

Electron. Lett (1)

M. Svalgaard, C. V. Poulsen, A. Bjarklev, and O. Poulsen, “Direct UV writing of buried single-mode channel waveguides in Ge-doped silica films,” Electron. Lett 30, 1401–1403 (1994).
[CrossRef]

IEEE Photon. Technol. Lett. (1)

D. O. Kundys, J. C. Gates, S. Dasgupta, C. Gawith, and P. Smith, “Use of cross-couplers to decrease size of UV written photonic circuits,” IEEE Photon. Technol. Lett. 21, 947–949 (2009).
[CrossRef]

J. Lightwave Technol. (1)

T. Erdogan, “Fiber grating spectra,” J. Lightwave Technol. 15, 1277–1294 (1997).
[CrossRef]

New J. Phys. (1)

G. Lepert, M. Trupke, M. J. Hartman, M. B. Plenio, and E. A. Hinds, “Arrays of waveguide-coupled optical cavities that interact strongly with atoms,” New J. Phys. 13, 113002 (2011).
[CrossRef]

Opt. Express (1)

Opt. Lett. (1)

Sens. Actuators B (1)

I. J. G. Sparrow, G. D. Emmerson, C. B. E. Gawith, and P. G. R. Smith, “Planar waveguide hygrometer and state sensor demonstrating supercooled water recognition,” Sens. Actuators B 107, 856–860 (2005).
[CrossRef]

Other (1)

M. Born and E. Wolf, Principles of Optics (Cambridge University Press, 1999)

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Figures (8)

Fig. 1
Fig. 1

Direct UV writing scheme using 244 nm light. The Bragg wavelength Λ of the gratings is determined by the angle 2θ between the two interfering beams according to Λ = 244 nm/(2sinθ)).

Fig. 2
Fig. 2

(a) Experimental reflection spectra of uniform (top) and apodised (bottom) gratings, written with duty cycles (fraction of time on) of 0.5 (red) or 0.8 (blue). Apodisation removes the side lobes and increases the bandwidth. Higher duty cycle results in weaker gratings. The two gratings were written on a single waveguide, their design wavelengths being 10 nm apart. (b) Mode profile of a UV-written waveguide, measured by scanning a single-mode fibre in front of the waveguide. The dashed white line is a fit to the 1/e2 contour. After de-convolving the 5.0μm fibre mode, this gives a waveguide mode diameter of 5.8μm by 4.5μm.

Fig. 3
Fig. 3

(a) Reflectivity (solid lines) and group delay (dashed) of uniform (blue) and Gaussian-apodised (red) Bragg gratings, plotted as a function of wavelength λ and frequency detuning from the peak Δν, calculated from coupled mode theory. Both gratings are 1.7mm or about 6350 periods long, and the index contrast is set to Δn = 3.8 × 10−4. The peak power reflection coefficients are 0.98 and 0.67 respectively. (b) Calculated transmission spectrum of a cavity made up of two such Gaussian-apodised gratings separated by 4mm. The blue curves shows the lossless case whereas the red curve includes realistic propagation losses of 0.9 dB/cm.

Fig. 4
Fig. 4

Schematic representation of the experimental setup. On the chip, a typical set of cavities with different grating and cavity lengths.

Fig. 5
Fig. 5

Six successive transmission spectra (frames) for the 16 mm waveguide cavity. The large overlap makes it possible to keep track of the slowly varying initial frequency. Inset: the laser diode temperature (Celsius) at which each frame was taken. The arrow indicates the order in which the frames were taken.

Fig. 6
Fig. 6

Data taken using a 16 mm long waveguide cavity with 1.7 mm-long gratings. (a) Log of intensity transmitted by cavity, reconstituted from 13 frames (out of 400), with gray/black parts denoting different frames. In the wings the transmission is close to 100%, at the centre it oscillates between 0.5% and 3%. (b) Black pluses show the coefficient of finesse F, blue crosses plot the free spectral range FSR, and red dots indicate the maximum transmitted intensity.

Fig. 7
Fig. 7

(a)–(c): free spectral range versus frequency for cavities of spacing (a) 16 mm, (b) 10 mm, and (c) 4 mm. Points: experimental data with uncertainties shown as shaded area. Dashed line: theoretical FSR derived from coupled mode theory. (d) Grating group delay τg. Blue crosses, red dots and green pluses are derived from the data in (a), (b) and (c) respectively, while the solid black line is calculated from coupled mode theory fitted to the data with index contrast as the only fit parameter. (e): Measured (solid) and theoretical (dashed line) finesse of the cavity in (b), fitted by adjusting the propagation loss and the index contrast.

Fig. 8
Fig. 8

(a) FSR−1 plotted versus length L for five cavities formed between 1.4 mm-long gratings and five using 1.8 mm-long gratings. Determination of group delay by extrapolating to FSR−1 = 0, indicated by red dots in the bottom left corner. (b) Evolution of group delay as the length of the grating increases. For the penultimate grating, two points are shown: one is derived from the three cavities of Fig. 7, while the second one uses a different set of data including all five cavities. The dashed line is a linear fit to the data. Red lines: coupled mode theory fro two values of index contrast.

Equations (2)

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I 1 + F sin 2 [ π ( ν FSR + ψ ) ]
τ g = 1 2 FSR n L c

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