290 fs switching time of Fe-doped quantum well saturable absorbers in a microcavity in 1.55μm range

Abstract

Ultrafast all-optical switch has been demonstrated by inserting Fe-doped multiple quantum wells (MQWs) in asymmetric Fabry-Perot microcavities. Heavy Fe doping during the InGaAs∕InP MQW epitaxial growth is a well-controlled technique to reach subpicosecond optical time constants. An asymmetric Fabry-Perot microcavity using gold metal as a back mirror and air/InP interface as a front mirror is realized. Pump-probe experiments using a conventional scheme on such switching devices are investigated. The device reveals an ultrafast response time, as low as 290fs, for an iron concentration of 2×1019cm−3, a contrast ratio of 8dB, a threshold switching fluence of 3.5μJ∕cm−2, and a 37-nm 3-dB bandwidth in the 1.55-μm telecommunication spectral range.

A direct comparison of single-walled carbon nanotubes and quantum-wells based subpicosecond saturable absorbers for all optical signal regeneration at 1.55 μm

“…Prior work has already demonstrated SA based on multiple-quantum-wells ͑MQW͒ InGaAs/InP with improved switching time dynamics. 2 This result has been obtained by exploring excitonic optical properties of MQW with high concentration of iron atoms ͑Fe͒. Fe atoms which act as recombination centers for photo-generated carriers in such two-dimensional-nanomaterials enabled to decrease the MQW photoresponse time from nanosecond range to subpicosecond scale.…”

HIGHLY FE-DOPED InGaAs/InP SATURABLE ABSORBER MODE-LOCKING OF AN ERBIUM FIBER LASER

“…time) SESATs with very high Fe-doping level. 25 Indeed, such in-microcavity structures show retrieved modulation depth properties even with very high iron concentrations. Very recently we have also tested 0.7 fs and 0.45 fs SESATs (both Fe-doped at a concentration around 8.5 × 10 18 cm −3 in the barriers and in the wells) without obtaining any stable mode-locking results.…”

All-Optical Sampling in a Multiple Quantum Well Saturable Absorber

“…For the MQW-SA setup the pulse width is overestimated because of the limited response time of the saturable absorber (5ps) and the short duration of the pulses (~2ps). This could be improved with the use of a faster saturable absorber such as those reported by M. Gicquel-Guezo et al [9], which have response times of 290fs.…”