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Optoelectronics, IEE Proceedings -

Issue 6 • Date Dec 1999

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Displaying Results 1 - 5 of 5
  • Facet coating effects on 1.3 and 1.55 μm strained multiple-quantum-well AlGaInAs/InP laser diodes

    Page(s): 268 - 272
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    The authors investigate the influence of facet reflectivity on the threshold current, light output power, characteristic temperature and slope efficiency drop for 1.3 and 1.55 μm strained multiple-quantum-well AlGaInAs-InP laser diodes (LDs) grown by low-pressure metalorganic vapor phase epitaxy. Remarkable improvements in maximum operation temperature, threshold current, slope efficiency drop, characteristic temperature and linearity of CW light-current characteristics have been demonstrated by increasing the reflectivity of the facet coating. By applying a high-reflectivity facet coating of 70-90% to the 1.3 μm LDs and 80-90% to the 1.55 μm LDs, lower threshold currents of 8.78 and 5.4 mA at 20°C, maximum operation temperatures of 165 and 155°C, lower slope efficiency drops of -0.7 and -0.9 dB, and higher characteristic temperatures of 92 and 88 K, respectively, can be obtained by decreasing the mirror loss. In addition, the LDs with facet coating can be operated for up to 10000 h at 10 mW and 85°C without significant degradation View full abstract»

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  • Adjustment of the chirp parameter of chirped fibre Bragg gratings

    Page(s): 263 - 267
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    A method for accurately adjusting the chirp parameter of the fabricated chirped fibre Bragg gratings (CFBGs) is demonstrated experimentally By establishing different strain gradient with proper profiles along the length of CFBGs, one can not only increase or decrease the chirp of the CFBG, but also change the sign of the chirp without exchanging the two ends of the grating. The variance of the chirp's amplitude can be accurately tuned through varying the amplitude of the strain gradient. Moreover, the grating's reflectivity hardly decreases and the shape of the reflection spectrum stays good during the adjustment of the chirp View full abstract»

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  • Experimental investigation of a Q-switched triple contact InGaAs bow-tie diode laser

    Page(s): 259 - 262
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    In this study the authors investigate high-energy picosecond pulse generation in a three contact two quantum well (QW) p-doped InGaAs bow-tie diode laser using a passive Q switching technique. Picosecond duration pulses with pulse energies of 39 pJ and peak powers in excess of 700 mW are obtained from the device in a well defined single lobed far-field. The pulses have typically 45 to 55 ps durations (FWHM). Unwanted tails can be presented by adjusting the reverse-bias voltage View full abstract»

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  • Analysing distributed feedback waveguides

    Page(s): 253 - 258
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    A method for analysing distributed feedback waveguides with arbitrary refractive index profiles is reported. The method considers a waveguide as a number of segments within which the reflection is weak, and thus the relevant transmission loss and multiple reflections can be neglected. By introducing a concept of reflective density formulas are derived for calculating the reflection and transmission coefficients and therefore the transfer matrix of an individual waveguide segment. The global reflection and transmission characteristics of the waveguide are then obtained by multiplying transfer matrices of all the waveguide segments together. The proposed method shows better accuracy than the coupled-mode method and requires less computation time than the effective-index method. The limitation of the coupled-mode method is shown both numerically and analytically for the first time and it is demonstrated that the coupled-mode method is only valid for analysing long Bragg gratings with particular initial phases View full abstract»

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  • Temperature dependence of the spontaneous emission factor in VCSELs

    Page(s): 245 - 251
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    The spontaneous emission factor β is studied as a function of temperature using k-, no k- and partial k-selection for bulk and multiquantum-well vertical-cavity surface-emitting lasers (VCSELs). This gives an improved insight into the behaviour of spontaneous emission as a function of temperature in such lasers where the resonant wavelength is chosen by the cavity and does not necessarily follow the peak gain. The calculated temperature dependence of the spontaneous emission factor exhibits a broad maximum associated with the alignment of the peak gain and cavity resonance. Spectral broadening effects affect this temperature dependence for the partial k-selection case at low temperatures where the cavity resonance lies within the low-energy spectral tail View full abstract»

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