Today fiber lasers in the visible to near-infrared region of the spectrum are well known, however mid-infrared fiber lasers have only recently approached the same commercial availability and power output. There has been a push to fabricate optical fiber lasers out of crystalline materials which have superior mid-IR performance and the ability to directly generate mid-IR light. However, these materials cannot currently be fabricated into an optical fiber via traditional means. We have used high pressure chemical vapor deposition (HPCVD) to deposit Fe2+:ZnSe into a silica optical fiber template. These deposited structures have been found to exhibit laser threshold behavior and emit CW mid-IR laser light with a central wavelength of 4.12 µm. This is the first reported solid state fiber laser with direct laser emission generated beyond 4 µm and represents a new frontier of possibility in mid-IR laser development.
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InAs-based interband cascade lasers (ICLs) can be more easily adapted toward long wavelength operation than their GaSb counterparts. Devices made from two recent ICL wafers with an advanced waveguide structure are reported, which demonstrate improved device performance in terms of reduced threshold current densities for ICLs near 11 μm or extended operating wavelength beyond 13 μm. The ICLs near 11 μm yielded a significantly reduced continuous wave (cw) lasing threshold of 23 A/cm2at 80 K with substantially increased cw output power, compared with previously reported ICLs at similar wavelengths. ICLs made from the second wafer incorporated an innovative quantum well active region, comprised of InAsP layers, and lased in the pulsed-mode up to 120 K at 13.2 μm, which is the longest wavelength achieved for III–V interband lasers.
- Award ID(s):
- Publication Date:
- NSF-PAR ID:
- Journal Name:
- Applied Physics Letters
- Page Range or eLocation-ID:
- Article No. 091105
- American Institute of Physics
- Sponsoring Org:
- National Science Foundation
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InAs-based interband cascade (IC) lasers with improved optical confinement have achieved high-temperature operation with a threshold current density as low as 333 A/cm2 at 300 K for emission at 6003 nm. The threshold current density is the lowest ever reported among semiconductor mid-infrared lasers at similar wavelengths. These InAs-based IC devices lased in pulsed mode at temperatures up to 357 K near 6.28 μm. A narrow-ridge device was able to operate in continuous-wave mode at temperatures up to 293 K at 6.01 μm.
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Mid-infrared photonic integrated circuits (PICs) that combine on-chip light sources with other optical components constitute a key enabler for applications such as chemical sensing, light detection, ranging, and free-space communications. In this paper, we report the monolithic integration of interband cascade lasers emitting at 3.24 µm with passive, high-index-contrast waveguides made of chalcogenide glasses. Output from the chalcogenide waveguides exhibits pulsed peak power up to 150 mW (without roll-over), threshold current density 280 A/cm2, and slope efficiency 100 mW/A at 300 K, with a lower bound of 38% efficiency for coupling between the two waveguides. These results represent an important step toward the realization of fully integrated mid-infrared PICs.
By studying two interband cascade laser (ICL) wafers with structural parameters that deviated considerably from the design, the durability of the device performance against structural variations was explored. Even with the lasing wavelength blue shifted by more than 700 nm from the designed value near 4.6 μm at 300 K, the ICLs still performed very well with a threshold current density as low as 320 A/cm2 at 300 K, providing solid experimental evidence of the tolerance of ICL performance on structural variations.