Showing papers by "Amnon Yariv published in 2017"
TL;DR: In a high power fiber amplifier, a frequency-chirped seed interrupts the coherent interaction between the laser and Stokes waves, raising the threshold for stimulated Brillouin scattering (SBS), resulting in a nearly-length-independent SBS threshold.
Abstract: In a high power fiber amplifier, a frequency-chirped seed interrupts the coherent interaction between the laser and Stokes waves, raising the threshold for stimulated Brillouin scattering (SBS). Moving the external mirror of a vertical cavity surface-emitting diode laser 0.2 μm in 10 μs can yield a frequency chirp of 5×1017 Hz/s at a nearly constant output power. Opto-electronic feedback loops can linearize the chirp, and stabilize the output power. The linear variation of phase with time allows multiple amplifiers to be coherently combined using a frequency shifter to compensate for static and dynamic path length differences. The seed bandwidth, as seen by the counter-propagating SBS, also increases linearly with fiber length, resulting in a nearly-length-independent SBS threshold. Experimental results at the 1.6 kW level with a 19 m delivery fiber are presented. A numerical simulation is also presented.
17 citations
TL;DR: In this paper, a narrow-linewidth heterogeneously integrated Si/III-V laser is presented, where the current confinement in the III-V structure is obtained by oxide isolation rather than by the prevailing ion-implantation technique.
Abstract: We demonstrate a narrow-linewidth heterogeneously integrated Si/III–V laser, where the current confinement in the III–V structure is obtained by oxide isolation rather than by the prevailing ion-implantation technique. This method provides effective electrical isolation as well as III–V surface passivation, and a pathway for high-efficiency diode injection laser performance. This method also offers increased compatibility with potentially high-temperature annealing processes. The lasers shown here possess a threshold current of as low as 60 mA and a single-facet output power of more than 3 mW at 20 °C. A linewidth of 28 kHz at 1574.8 nm is obtained at a current of 200 mA ( $I = 3.3 \times I_{\mathrm{ th}}$ ). Single-mode operation is achieved with a side-mode suppression ratio larger than 55 dB.
12 citations
14 May 2017
TL;DR: In this article, the authors observed a relaxation resonance frequency of hundreds of MHz in high-coherence Si/III-V laser, up to 5× less than commercial III-V lasers.
Abstract: We observe a relaxation resonance frequency of hundreds of MHz in high-coherence Si/III-V lasers, up to 5× less than commercial III-V lasers. This results in very noise frequency noise PSD of 720 Hz2/Hz above the relaxation resonance frequency due to the suppression of linewidth enhancement factor.
2 citations
14 May 2017
TL;DR: In this article, a narrow-linewidth heterogeneously integrated silicon/III-V laser based on the oxide-confinement method was demonstrated, achieving an output power of 4 mW and a linewidth of 28 kHz with a threshold current of 60 mA and a side mode suppression ratio of 50 dB at 1574 nm.
Abstract: We demonstrate a narrow-linewidth heterogeneously integrated silicon/III-V laser based on the oxide-confinement method. The laser achieves an output power of 4 mW and a linewidth of 28 kHz with a threshold current of 60 mA and a side mode suppression ratio of 50 dB at 1574 nm.
2 citations
14 May 2017
TL;DR: In this article, the feedback sensitivity of a high coherence silicon/III-V laser is quantified using an interferometer, and high fringe visibility is maintained up to at a reflectivity of −21 dB, a 10 dB improvement compared to a high end commercially available DFB laser.
Abstract: The feedback sensitivity of a high coherence silicon/III-V laser is quantified using an interferometer. High fringe visibility is maintained up to at a reflectivity of −21 dB, a 10 dB improvement compared to a high end commercially available DFB laser.
1 citations
01 Jan 2017
TL;DR: In this article, the authors proposed a coherent array where each element has a separate contact, which can be employed to tailor the near-field and far-field distributions and compensate for device-to-device nonuniformities.
Abstract: Coherent combination of the power of several semiconductor lasers fabricated on the same substrate has been the subject of an intense research effort in recent years, the main moti vation being to obtain higher power levels than those available from a single laser in a stable radiation pattern. Best results reported so far include 2.6 Watts cw emitted power and less than 1° far-field angle (in the array plane) in arrays where all the lasers are electrically connected in parallel. A different type of coherent array, where each element has a separate contact, has been recently demonstrated. While requiring the more complex two-level metallization technology, applying a separate contact to each laser provides an additional degree of freedom in the design and the operation of monolithic arrays. The separate contacts can be employed to tailor the near-field and far-field distributions and to compensate for device-to-device nonuniformities. Furthermore, the control of the cur rents of the array elements allows the performance of a variety of other functions, such as beam scanning, spectral mode control, wavelength tuning and control of the mutual coherence between array elements.
01 Mar 2017
TL;DR: In this paper, a high-power fiber amplifier with a frequency-chirped seed interrupts the coherent interaction between the laser and Stokes waves, raising the threshold for stimulated Brillouin scattering (SBS).
Abstract: : In a high-power fiber amplifier, a frequency-chirped seed interrupts the coherent interaction between the laser and Stokes waves, raising the threshold for stimulated Brillouin scattering (SBS). Moving the external mirror of a vertical cavity surface-emitting diode laser 0.2 m in 10 s can yield a frequency chirp of 5 1017 Hz/s at a nearly constant output power. Opto-electronic feedback loops can linearize the chirp and stabilize the output power. The simple and deterministic variation of phase with time preserves temporal coherence, in the sense that it is straightforward to coherently combine multiple amplifiers despite a large path-length mismatch. The seed bandwidth, as seen by the counterpropagating SBS, also increases linearly with fiber length, resulting in a nearly length-independent SBS threshold. Experimental results at the 1.6-kW level with a 19-m delivery fiber are presented. A numerical simulation is also presented.