In this work we present a study on teh Super Luminescent LIght Emitting Diodes (SLEDs) performance under high doses of gamma radiation. We investigate GaAs SLEDs with emission wavelengths around 830 nm. The devices were exposed to ionising radiation at a dose rate of about 4.7 Gy/s, up to a cumulated dose of 10.1 MGy in the CMF facility of the Belgian nuclear research centre SCK•CEN. We measured the device characteristics before adn after irradiation. We show that the SLED performance is only marginally affected.
We have fabricated superluminescent light-emitting devices in the 840nm wavelength range with flat top spectral shape.
The novel design allows more than 50nm bandwidth and up to 34mW of optical power at the chip facet. Moreover, the
3dB bandwidth changes by less than 2nm within a driving current range between 120mA and 200mA. This corresponds
to a power level change between 17mW and 34mW, without considerable shape changes, which is one of the main
concerns for many applications. The stability of the spectral bandwidth is also reflected by the central wavelength that
changes by less than 1nm in the same range of currents. The device shows great stability of the optical far field with
respect to the driving current, allowing stable coupling of the emitted beam in optical fibers. We have also measured the
coherence function of this device using an interferometric spectrum analyzer. Results show good side-lobes suppression
ratio of more than 10dB, which remains almost unchanged over the whole range of driving currents.
A super-luminescent light emitting diode (SLED) operating around 1300nm is simulated. This edge-emitting device is grown on an InP substrate and comprises multiple quantum wells. For the simulation the focus is put on the amplified spontaneous emission (ASE) spectra for different input currents as well as on the output power vs. current curves (light vs. current---LI). Simulated ASE spectra agree very well with measurements over a large wavelength range (more than 80nm). Regarding the LI-characteristics good agreement between simulations and measurements is obtained for input currents from 10mA up to 150mA. The simulated electrical characteristics of the device are obtained by solving drift-diffusion equations, the optical problem is solved by decomposing the vectorial (3D) Helmholtz equation into a transverse and into a longitudinal part.
A Superluminescent Light Emitting Diode (SLED) is an ideal optical broadband source for applications like Optical Coherence Tomography (OCT) and other fiber optic based imaging techniques. High optical output power and large optical bandwidth are key features for these devices. The short coherence length related to this large bandwidth allows the realization of OCT systems with higher sensitivity.
Semiconductor devices based on quantum dots (QD) are ideally suited as the active material for SLEDs since the size dispersion typical of self-assembled growth naturally produces a large inhomogeneous broadening. The large spacing between different energy levels can lead to improved thermal stability as well.
In this paper we report, ridge-waveguide devices based on five stacks of self-assembled InAs/GaAs QDs. SLED devices with output powers up to 1.5 mW emitting around 1300 nm have been realized. Spectral analysis at 20°C shows a 121 nm FWHM. Temperature characteristics in the range 10-80°C are also reported.
A Superluminescent Light Emitting Diode (SLED) is an ideal optical broadband source for applications like Fiber Optic Gyroscopes and other fiber optic based sensors used in navigation systems. High optical output power and large optical bandwidth are key features for these devices. The short coherence length related to this large bandwidth allows the realization of sensors with improved sensitivity.
Semiconductor devices based on quantum dots (QD) are ideally suited as the active material for SLEDs since the size dispersion typical of self-assembled growth naturally produces a large inhomogeneous broadening. The large spacing between different energy levels can lead to improved thermal stability as well. In this paper we report, ridge-waveguide devices based on five stacks of self-assembled InAs/GaAs QDs. SLED devices with output powers up to 1.5 mW emitting around 1300 nm have been realized. Spectral analysis at 20°C shows a 121 nm FWHM. Temperature characteristics in the range 10-80°C are also reported.
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