Research ArticleAPPLIED SCIENCES AND ENGINEERING

Toward continuous-wave operation of organic semiconductor lasers

See allHide authors and affiliations

Science Advances  28 Apr 2017:
Vol. 3, no. 4, e1602570
DOI: 10.1126/sciadv.1602570
  • Fig. 1 Fabrication method of the organic semiconductor DFB lasers.

    Schematic representation of the method used to fabricate the organic DFB lasers. The different successive steps involve the fabrication of the DFB resonator structure by electron beam (e-beam) lithography, thermal evaporation of the organic semiconductor thin film, and spin coating of CYTOP polymer film followed by device sealing with a high–thermal conductivity (TC) sapphire lid.

  • Fig. 2 Structure of the mixed-order DFB resonators.

    (A) Schematic representation of the mixed-order DFB grating structure used in this study. SEM images with (B) ×2500 and (C) ×100,000 magnification and (D) SEM image and (E) cross-sectional SEM image of the device after the deposition of a 200-nm-thick BSBCz:CBP blend film.

  • Fig. 3 Lasing properties of organic DFB lasers in the qCW regime.

    Streak camera images showing laser oscillations from a representative BSBCz:CBP encapsulated mixed-order DFB device at repetition rates from 0.01 to 80 MHz over a period of (A) 500 μs or (B) 200 ns (80 MHz only). Excitation intensity was fixed at ~0.5 μJ cm−2, which is higher than the lasing threshold (Eth). (C) Temporal evolution of laser output intensity at various repetition rates (f) in an encapsulated BSBCz:CBP mixed-order DFB laser. (D) Lasing threshold in several types of DFB devices as a function of repetition rate. Lines serve as visual guidelines.

  • Fig. 4 Lasing properties of organic DFB lasers in the long-pulse regime.

    (A) Streak camera images showing laser emission integrated over 100 pulses from an encapsulated mixed-order DFB device using a BSBCz:CBP (20:80 wt %) film as gain medium and optically pumped by pulses of 30 ms and 2.0 kW cm−2 (top) or 800 μs and 200 W cm−2 (bottom). (B) Photograph of DFB device operating in the long-pulse regime (excitation, 30 ms). (C) Lasing threshold (Eth) in various DFB devices as a function of excitation duration. Dotted lines serve as visual guidelines. (D) Change in laser output intensity from organic DFB lasers as a function of the number of incident pulses (100 μs and 200 W cm−2).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/4/e1602570/DC1

    section S1. Optical simulations

    section S2. Lasing properties of mixed-order DFB devices

    section S3. Optical gain

    section S4. Transient absorption

    section S5. Thermal simulations

    fig. S1. Schematic of the geometry used for optical simulation.

    fig. S2. Lasing threshold of mixed-order DFB lasers based on BSBCz:CBP (6:94 wt %) 200-nm-thick film for different dimensions of the second-order gratings.

    fig. S3. Photophysical properties of films with and without encapsulation.

    fig. S4. Characterization of the pulsed organic lasers.

    fig. S5. qCW lasing threshold.

    fig. S6. Lasing threshold measured in forward (increasing repetition rate) and reverse (decreasing repetition rate) directions as a function of the repetition rate.

    fig. S7. Significant reduction of degradation in encapsulated DFB devices.

    fig. S8. Stability of the qCW laser.

    fig. S9. Optical net gain under long-pulse operation.

    fig. S10. Emission spectra of encapsulated 20 wt % blend mixed-order DFB lasers measured at a pumping intensity of 200 W cm−2 and 2.0 kW cm−2 for long-pulse durations of 800 μs and 30 ms, respectively.

    fig. S11. Streak camera image showing laser emission integrated over 100 pulses from an encapsulated mixed-order DFB device during a 30-ms-long photoexcitation with a pump power of 2.0 kW cm−2.

    fig. S12. Lack of triplet losses in the gain medium.

    fig. S13. Divergence of DFB laser.

    fig. S14. Polarization of DFB laser.

    fig. S15. Lasing threshold under long-pulse operation.

    fig. S16. Excitation duration dependence of the lasing threshold.

    fig. S17. Laser-induced thermal degradation.

    fig. S18. Schematic of the geometry used for thermal simulation.

    fig. S19. Maximum temperature rise at the end of each pulse.

    fig. S20. Temperature rise as a function of time with different pulse widths.

    fig. S21. Temperature rise as a function of time for a pulse width of 10 ms in the devices with and without encapsulation.

    fig. S22. Temperature rise as a function of time or number of pulses of τp = 30 ms in the gain region.

    table S1. Film thickness, lasing wavelength, confinement factor, and quality factor.

    table S2. Grating depth, lasing wavelength, confinement factor, and quality factor.

    table S3. Comparison between devices with and without encapsulation, lasing wavelength, confinement factor, and quality factor.

    table S4. Pulse width, excitation power, net gains, and loss coefficient.

    table S5. Thermophysical and geometrical parameters of the materials.

    References (5052)

  • Supplementary Materials

    This PDF file includes:

    • section S1. Optical simulations
    • section S2. Lasing properties of mixed-order DFB devices
    • section S3. Optical gain
    • section S4. Transient absorption
    • section S5. Thermal simulations
    • fig. S1. Schematic of the geometry used for optical simulation.
    • fig. S2. Lasing threshold of mixed-order DFB lasers based on BSBCz:CBP (6:94 wt %) 200-nm-thick film for different dimensions of the second-order gratings.
    • fig. S3. Photophysical properties of films with and without encapsulation.
    • fig. S4. Characterization of the pulsed organic lasers.
    • fig. S5. qCW lasing threshold.
    • fig. S6. Lasing threshold measured in forward (increasing repetition rate) and reverse (decreasing repetition rate) directions as a function of the repetition rate.
    • fig. S7. Significant reduction of degradation in encapsulated DFB devices.
    • fig. S8. Stability of the qCW laser.
    • fig. S9. Optical net gain under long-pulse operation.
    • fig. S10. Emission spectra of encapsulated 20 wt % blend mixed-order DFB lasers measured at a pumping intensity of 200 W cm−2 and 2.0 kW cm−2 for long-pulse durations of 800 μs and 30 ms, respectively.
    • fig. S11. Streak camera image showing laser emission integrated over 100 pulses from an encapsulated mixed-order DFB device during a 30-ms-long photoexcitation with a pump power of 2.0 kW cm−2.
    • fig. S12. Lack of triplet losses in the gain medium.
    • fig. S13. Divergence of DFB laser.
    • fig. S14. Polarization of DFB laser.
    • fig. S15. Lasing threshold under long-pulse operation.
    • fig. S16. Excitation duration dependence of the lasing threshold.
    • fig. S17. Laser-induced thermal degradation.
    • fig. S18. Schematic of the geometry used for thermal simulation.
    • fig. S19. Maximum temperature rise at the end of each pulse.
    • fig. S20. Temperature rise as a function of time with different pulse widths.
    • fig. S21. Temperature rise as a function of time for a pulse width of 10 ms in the devices with and without encapsulation.
    • fig. S22. Temperature rise as a function of time or number of pulses of τp = 30 ms in the gain region.
    • table S1. Film thickness, lasing wavelength, confinement factor, and quality factor.
    • table S2. Grating depth, lasing wavelength, confinement factor, and quality factor.
    • table S3. Comparison between devices with and without encapsulation, lasing wavelength, confinement factor, and quality factor.
    • table S4. Pulse width, excitation power, net gains, and loss coefficient.
    • table S5. Thermophysical and geometrical parameters of the materials.
    • References (50–52)

    Download PDF

    Files in this Data Supplement:

Navigate This Article