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Optics Express

Optics Express

  • Editor: C. Martijin de Sterke
  • Vol. 15, Iss. 9 — Apr. 30, 2007
  • pp: 5604–5609
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Single mode condition and modes discrimination in photonic-crystal 1.3 μm AlInGaAs/InP VCSEL

Tomasz Czyszanowski, Maciej Dems, and Krassimir Panajotov  »View Author Affiliations


Optics Express, Vol. 15, Issue 9, pp. 5604-5609 (2007)
http://dx.doi.org/10.1364/OE.15.005604


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Abstract

We determine the single mode condition and analyze the modes discrimination of 1.3 μm InP based photonic-crystal vertical-cavity surface-emitting diode laser. To this aim we apply the fully vectorial, three dimensional Plane Wave Admittance Method and analyze a broad range of photonic-crystal parameters such as hole etching depth, distance between the holes and their diameters.

© 2007 Optical Society of America

1. Introduction

The photonic-crystal (PC) vertical-cavity surface-emitting diode lasers (VCSELs) are very perspective light sources for telecommunication applications [1

1. H. Li and K. Iga, Vertical-Cavity Surface-Emitting Laser Devices, (Berlin: Springer-Verlang, 2003).

]. Therefore crucial is the determination of the laser parameters, which support the single mode operation. Several experimental reports proved the ability of single mode operation of PC VCSEL structures. A maximum output power of 3.1 mW and 1mW in the fundamental mode has been achieved for a single-defect PC VCSEL emitting at 0.85 μm [2

2. A. J. Danner, T. S. Kim, and K. D. Choquette, “Single fundamental mode photonic crystal vertical cavity laser with improved output power,” Electron. Lett. 41, 325 – 326 (2005). [CrossRef]

] and 1.3 μm [3

3. P. O. Leisher, A. J. Danner, and K. D. Choquette, “Single-Mode 1.3-μm Photonic Crystal Vertical-Cavity Surface-Emitting Laser,” IEEE Photon. Technol. Lett. 18, 2156 – 2158 (2006). [CrossRef]

], respectively. The structure of the photonic-crystal is defined by three independent parameters: the distance between the PC holes (L), the diameter of the holes (a) and their etching depths. Hence all three parameters have to be analyzed to determine the PC parameters supporting single mode operation. The first attempts toward the determination of the single mode condition have been performed in Refs. [4

4. N. Yokouchi, A. J. Danner, and K. D. Choquette “Etching depth dependence of the effective refractive index in two-dimensional photonic-crystal-patterned vertical-cavity surface-emitting laser structures,” Appl. Phys. Lett. 82, 1344 – 1346 (2003). [CrossRef]

, 5

5. S. Ivanov, H. J. Unold, R. Michalzik, J. Maehnss, K. J. Ebeling, and I. A. Sukhoivanov, “Theoretical study of cold-cavity single-mode conditions in vertical-cavity surface-emitting lasers with incorporated two-dimensional photonic crystals,” J. Opt. Soc. Am. B 20, 2442 – 2447 (2003). [CrossRef]

]. The first one has been based on 2D plane-wave expansion and a correction to the effective refractive index corresponding to finite depths of the holes and the second on the scalar, effective index method. Both of them however suffered the lack of fully vectorial, three dimensional, optical analysis, which is performed here.

2. Laser structure

Fig. 1. (a). Schematic view of the bottom-emitting 1300-nm InP-based AlGaInAs quantum well (QW) PC VCSEL design. The photonic-crystal (PC) is shown as straight air columns surrounding the central part of the VCSEL cavity and etched throughout the upper DBR, (b). the typical intensity distribution of the fundamental mode within the active region and the first ring of the photonic crystal. The diameter of the hole (a) the distance between the hole axes - the pitch (L) and the optical aperture (2 RA) are defined.

3. Results

Fig. 2. Region of single mode operation (gray fields) for six different optical apertures (from RA = 1 μm to RA = 6 μm) a) - f) mapped in the plane of etching depth and a/L ratio. The horizontal lines assign the PC parameters, which have been chosen in the analysis presented in Figs. 3 and 4.

3.1 Single mode operation

Figure 2 illustrates the area of a single mode (s-m) operation region, which exists in a broad range of PC parameters. The s-m region is shown as gray area. From below it is limited by the cut-off etching depth, i.e. the depth for which well-confined mode in the PC defect appears [10

10. T. Czyszanowski, M. Dems, and K. Panajotov “Optimal parameters of Photonic-Crystal Vertical-Cavity Surface-Emitting Diode Lasers,” accepted by IEEE J. Lightwave Technol.

]. From above it is limited by the cut-off etching depth for the first higher order mode. As it can be seen from Fig. 2 the s-m region is the largest for a/L ratios as in this case it is not limited from above by the appearance of first order mode. This “extended” s-m region is shifted toward smaller a/L ratios and is squeezed with the increase of RA: in the case of RA = 1 μm the s-m region is limited by 0.2 < a/L < 0.5 while for broad optical aperture (RA = 6 μm) by 0.1 < a/L< 0.2. For the remaining stripe of s-m region one can notice from Fig. 2 that its thickness is almost the same for different RA. It is approximately equal to 0.5 μm and does not depend on a/L. Only in the extreme case of RA = 1 μm it is somewhat thicker and approximately equals 1 μm. The position of the s-m region is shifted toward shallower etching depth with the increase of RA and a/L. However, the dependence on a/L is weak and for a/L > 0.6 the shift is insignificant. The described variation of the position and the area of s-m region are governed mostly by the change of the PC induced waveguiding. If it is stronger, the single mode region is shifted toward smaller a/L and shallower etching depths.

3.2. Mode discrimination

Figures 3(a) and 3(b) illustrates the influence of the etching depth on the wavelength of the emission for different configurations of PC parameters. The chosen characteristics correspond to the PC parameters assigned by the vertical lines in Figs. 2(b), 2(d)–2(f). The reduction of the aperture size contributes to a pronounced blue shift. Similar effect causes the increase of the a/L ratio however, not in the same extend. This can be explained since the reduction of the aperture as well as the broadening of the holes causes a spatial shrinkage of the mode as well as better discrimination of the modes (larger wavelength difference) as also observed for oxide-confined VCSELs [11

11. T. Czyszanowski and W. Nakwaski “Usability limits of the scalar effective frequency method used to determine modes distributions in oxide-confined vertical-cavity surface-emitting diode lasers,” J. Phys. D: Appl. Phys. 39, 30 – 35 (2006). [CrossRef]

]. Figures 3(c) and 3(d) present the discrimination of the modes with respect to the real part of eigen-wavelength. The largest discrimination is observed in the case of deep, broad holes and narrow apertures. In those case the impact of the PC holes is the strongest.

In the multimode region, but close to the single mode one, the first order mode is weakly confined by the PC, hence it suffers high losses, while the fundamental mode is relatively well localized into the active region (Fig. 5). The reduction of the mode discrimination is due to the improvement of the confinement for both HE11 and HE21 modes (Fig. 6). Therefore the largest discrimination of the modes is observed for narrow optical apertures as well as for narrow and/or shallow holes.

Fig. 3. Fundamental mode wavelength [(a) and (b)] and mode discrimination for the real eigen-wavelength [(c) and (d)] versus etching depth, under a change of the optical aperture (RA) [(a) and (c)] and the a/L ratio [(b) and (d)].
Fig. 4. The difference of the modal gains αm0 and αm1 of the fundamental and the first order mode versus etching depth, under a change of (a) optical aperture and b) a/L ratio. Dots in (a) relates to the PC parameters used in Figs. 5 and 6.
Fig. 5. Distribution of a) HE11 and b) HE21 mode within active region for 6.5 μm etching depth and PC parameters determined in Fig. 4(a) by the large black dots.
Fig. 6. Distribution of a) HE11 and b) HE21 mode within active region for 12.4 μm etching depth and PC parameters determined in the Fig. 4(a) by the corresponding dot.

4. Conclusions

Acknowledgment

This work was supported by Foreign Fellowships for Young PhD’s awarded by Foundation for Polish Science, grant No N515 004 32/0297 from the Polish Ministry of Science and Higher Education (MNiSzW), IAP Program of the Belgian government, COST P11, as well as GOA, FWO, and OZR of the VUB.

References and links

1.

H. Li and K. Iga, Vertical-Cavity Surface-Emitting Laser Devices, (Berlin: Springer-Verlang, 2003).

2.

A. J. Danner, T. S. Kim, and K. D. Choquette, “Single fundamental mode photonic crystal vertical cavity laser with improved output power,” Electron. Lett. 41, 325 – 326 (2005). [CrossRef]

3.

P. O. Leisher, A. J. Danner, and K. D. Choquette, “Single-Mode 1.3-μm Photonic Crystal Vertical-Cavity Surface-Emitting Laser,” IEEE Photon. Technol. Lett. 18, 2156 – 2158 (2006). [CrossRef]

4.

N. Yokouchi, A. J. Danner, and K. D. Choquette “Etching depth dependence of the effective refractive index in two-dimensional photonic-crystal-patterned vertical-cavity surface-emitting laser structures,” Appl. Phys. Lett. 82, 1344 – 1346 (2003). [CrossRef]

5.

S. Ivanov, H. J. Unold, R. Michalzik, J. Maehnss, K. J. Ebeling, and I. A. Sukhoivanov, “Theoretical study of cold-cavity single-mode conditions in vertical-cavity surface-emitting lasers with incorporated two-dimensional photonic crystals,” J. Opt. Soc. Am. B 20, 2442 – 2447 (2003). [CrossRef]

6.

www.oxfordplasma.de/process/inp_phcr.htm

7.

T. Czyszanowski, M. Dems, and K. Panajotov “Improvement of the beam quality in the long wavelength photonic crystal VCSEL,” submitted to Opt. Express

8.

T. Czyszanowski, M. Dems, H. Thienpont, and K. Panajotov “Optimal radii of Photonic Crystal holes within DBR mirrors in long wavelength VCSEL,” Opt. Express 15, 1301–1306 (2007). [CrossRef] [PubMed]

9.

M. Dems, R. Kotynski, and K. Panajotov “Plane Wave admittance method — a novel approach for determining the electromagnetic modes in photonic structures,” Opt. Express 13, 3196 – 3207 (2005). [CrossRef] [PubMed]

10.

T. Czyszanowski, M. Dems, and K. Panajotov “Optimal parameters of Photonic-Crystal Vertical-Cavity Surface-Emitting Diode Lasers,” accepted by IEEE J. Lightwave Technol.

11.

T. Czyszanowski and W. Nakwaski “Usability limits of the scalar effective frequency method used to determine modes distributions in oxide-confined vertical-cavity surface-emitting diode lasers,” J. Phys. D: Appl. Phys. 39, 30 – 35 (2006). [CrossRef]

OCIS Codes
(140.3430) Lasers and laser optics : Laser theory
(140.5960) Lasers and laser optics : Semiconductor lasers
(250.7260) Optoelectronics : Vertical cavity surface emitting lasers

ToC Category:
Lasers and Laser Optics

History
Original Manuscript: March 1, 2007
Revised Manuscript: April 16, 2007
Manuscript Accepted: April 17, 2007
Published: April 24, 2007

Citation
Tomasz Czyszanowski, Maciej Dems, and Krassimir Panajotov, "Single mode condition and modes discrimination in photonic-crystal 1.3 μm AlInGaAs/InP VCSEL," Opt. Express 15, 5604-5609 (2007)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-15-9-5604


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References

  1. H. Li and K. Iga, Vertical-Cavity Surface-Emitting Laser Devices, (Berlin: Springer-Verlang, 2003).
  2. A. J. Danner, T. S. Kim, and K. D. Choquette, "Single fundamental mode photonic crystal vertical cavity laser with improved output power," Electron. Lett. 41, 325 - 326 (2005). [CrossRef]
  3. P. O. Leisher, A. J. Danner, and K. D. Choquette, "Single-Mode 1.3-μm Photonic Crystal Vertical-Cavity Surface-Emitting Laser," IEEE Photon. Technol. Lett. 18, 2156 - 2158 (2006). [CrossRef]
  4. N. Yokouchi, A. J. Danner, and K. D. Choquette "Etching depth dependence of the effective refractive index in two-dimensional photonic-crystal-patterned vertical-cavity surface-emitting laser structures," Appl. Phys. Lett. 82, 1344 - 1346 (2003). [CrossRef]
  5. S. Ivanov, H. J. Unold, R. Michalzik, J. Maehnss, K. J. Ebeling, and I. A. Sukhoivanov, "Theoretical study of cold-cavity single-mode conditions in vertical-cavity surface-emitting lasers with incorporated two-dimensional photonic crystals," J. Opt. Soc. Am. B 20, 2442 - 2447 (2003). [CrossRef]
  6. www.oxfordplasma.de/process/inp_phcr.htm
  7. T. Czyszanowski, M. Dems, and K. Panajotov "Improvement of the beam quality in the long wavelength photonic crystal VCSEL," submitted to Opt. Express
  8. T. Czyszanowski, M. Dems, H. Thienpont, and K. Panajotov "Optimal radii of Photonic Crystal holes within DBR mirrors in long wavelength VCSEL," Opt. Express 15, 1301-1306 (2007). [CrossRef] [PubMed]
  9. M. Dems, R. Kotynski, and K. Panajotov "Plane Wave admittance method — a novel approach for determining the electromagnetic modes in photonic structures," Opt. Express 13, 3196 - 3207 (2005). [CrossRef] [PubMed]
  10. T. Czyszanowski, M. Dems, and K. Panajotov " Optimal parameters of Photonic-Crystal Vertical-Cavity Surface-Emitting Diode Lasers," accepted by IEEE J. Lightwave Technol.
  11. T. Czyszanowski and W. Nakwaski "Usability limits of the scalar effective frequency method used to determine modes distributions in oxide-confined vertical-cavity surface-emitting diode lasers," J. Phys. D: Appl. Phys. 39, 30 - 35 (2006). [CrossRef]

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