Quantum cascade lasers and the Kruse model in free space optical communication

Abstract

Mid-infrared (MIR) free space optical communication has seen renewed interest in recent years due to advances in quantum cascade lasers. We present data from a multi-wavelength test-bed operated in the New York metropolitan area under realistic weather conditions. We show that a mid-infrared source (8.1 microm) provides enhanced link stability with 2x to 3x greater transmission over near infrared wavelengths (1.3 microm & 1.5 microm) during fog formation and up to 10x after a short scavenging rain event where fog developed and visibility reduced to approximately 1 km. We attribute the improvement to less Mie scattering at longer wavelengths. We confirm that this result is generally consistent with the empirical benchmark Kruse model at visibilities above 2.5 km, but towards the 1 km eye-seeing limit we measured the equivalent MIR visibility to be > 10 km.

Analysis and evaluation of optimum wavelengths for free-space optical transceivers

“…This MIR signal can be greater than traditional NIR wavelengths by a wide margin at the onset of fog (V = 1.05 km) by a factor of over 10 dB/km (see Fig. 2) [12]. [12].…”

“…However, the realization of optical communications at the longer wavelengths has encountered significant difficulties due to lack of adequate optical sources and detectors operating in the desirable wavelength regions [16]. Corrigan [12] has now confirmed the advantages of longer wavelengths in his study. They constructed a 550 m outdoor, multi-wavelength FSO link at the laser frequencies of 1.345, 1.558 and 8.1 µm.…”

“…Mid-Wavelength Infra Red (MWIR) and Long Wavelength Infra Red band (LWIR) FSO communications encountered evolving interest in recent years due to the advances in quantum cascade lasers and progress in mercury cadmium telluride (HgCdTe) photodiodes and quantum well infrared photo detectors [12], [13]. The use of 10 µm wavelength was already in discussion in the beginning of the 1980's.…”

“…2) [12]. [12]. Now, there exist already several works related to FSO data link using quantum cascade lasers.…”

Quantum Confinement in High Electron Mobility Transistors

“…One of the very common and sophisticated examples in this regard is the quantum cascade laser [7][8][9], which is based on the cascade phenomena and intersubband transitions across many layers of quantum wells. Such compact and powerful lasers are used for practical applications in THz spectroscopy [10][11][12][13], sensing technology [14,15], biomedical applications [16,17] and also in security applications [11,18]. Structures based on quantum wells have also made significant advancement in the detector technology, for example, quantum well infrared photodetectors [19,20].…”