High peak-power picosecond pulse generation at 126 µm using a quantum-dot-based external-cavity mode-locked laser and tapered optical amplifier

Abstract

Abstract:In this paper, we present the generation of high peak-power picosecond optical pulses in the 1.26 μm spectral band from a repetitionrate-tunable quantum-dot external-cavity passively mode-locked laser (QD-ECMLL), amplified by a tapered quantum-dot semiconductor optical amplifier (QD-SOA). The laser emission wavelength was controlled through a chirped volume Bragg grating which was used as an external cavity output coupler. An average power of 208.2 mW, pulse energy of 321 pJ, and peak power of 30.3 W were achieved. Preliminary nonlinear imaging investigations indicate that this system is promising as a high peak-power pulsed light source for nonlinear bio-imaging applications across the 1.0 μm -1.3 μm spectral range.

Unlocking Spectral Versatility from Broadly−Tunable Quantum−Dot Lasers

“…QD lasers on the other hand have a smaller footprint, are less complex and less costly and so are suitable replacements especially when tuned to the same range of wavelengths. Very promising results were achieved with multi−photon imaging at fixed wavelength using a mode−locked QD laser system [15], and one could anticipate that the tunability demonstrated before could also be exploited into a more flexible multi−photon configuration [58], where the wavelength could be tuned to target the chromophores of interest. The first demonstration of second−harmonic generation with a broadly tunable QD laser has enabled the access to the yellow spectral region via coupling into an enhancement cavity containing a periodically−poled LiNbO 3 (bulk) crystal [44].…”

“…Such broadly−tunable lasers have a wide range of applications including spectroscopy [12], frequency doubling [13] and biomedical imaging modalities such as optical coherence tomography [14], as the wavelength range between 1-1.3 μm overlaps with regions of deep tissue penetration with minimal scattering. For this reason, QD lasers are also extremely promising laser sources for multiphoton microscopy, as recently demonstrated [15]. Moreover, their lower cost, complexity and footprint would also address the major shortcomings associated with the lasers currently used, which are bulky and high cost, as currently discussed in the bio−imaging community [16].…”

Ultra‐Short‐Pulse QD Edge‐Emitting Lasers

“…Semiconductor laser diode systems with amplification schemes have been already successfully demonstrated as light sources for nonlinear microscopy applications [67,74,75]. However, these laser diode systems typically involved two or more amplification stages and additional extracavity dispersion compensation schemes that make the system more complex [76].…”

“…In the following, the first semiconductor pulsed laser with pulse widths and FOM characteristics compatible with nonlinear microscopy applications is discussed, whereby this system operates at a very low repetition rate of 648 MHz and which employs only one amplification stage and which is not dependent on external additional pulse compression techniques [76].…”

“…As in Section 2.7.1, the waveguide of the gain section is terminated at an angle of 7 • relative to the cleaved facet and equipped with an AR coating (R ∼ 10 −5 ) whereas the back facet is HR coated (R ∼ 95%). The active regions of both gain chip and tapered QD-SOA contain 10 layers QDs [76]. The CBG is a reflective Bragg grating inscribed in photothermal-refractive glass, and exhibits a center wavelength of about 1262 nm and a diffraction efficiency of around 12-15%.…”