Μm Er Research Articles

Hydrogen Passivation Of Er-Doped AIN

AbstractAIN(Er) doped with Er during Metal Organic Molecular Beam Epitaxy has been plasma hydrogenated in-situ at 200–250°C using an Electron Cyclotron Resonance source. By isotopic substitution of 2H for 1H, we have found from Secondary Ion Mass Spectrometry profiling that a 30 min hydrogenation treatment can incorporate ˜2×1019cm−3 deuterium atoms to depths ≥1μm. The intensity of the 1.54μm Er3+ luminescence is increased by a factor of ˜5 by the 200°C hydrogenation, and this effect is thermally stable to 300°C, indicating a binding energy of >1.5eV for hydrogen at defects in the AIN. These defects would normally either be recombination centers or provide an alternative de-excitation path for the Er. We have previously found that AIN provides the best resistance to thermal quenching of Er luminescence of any semiconductor due to its wide bandgap. Together, these results suggest that AIN(Er) may be a promising material for optical control of devices such as light-triggered SiC or GaN thyristors for power switching applications, where a fiber-transmitted signal from temperaturetolerant material is necessary in controlling power distribution grids. Hydrogen does not leave the AIN until ˜800°C and presumably forms an intermediate state such as H2 or larger clusters prior to evolution from the surface, and again this stability is among the best for any semiconductor.

Composition dependence of room temperature 1.54μm Er3+ luminescence from erbium doped silicon:oxygen thin films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition

AbstractThe composition dependence of room temperature 1.54 μ Er3+ photoluminescence of erbium doped silicon:oxygen thin films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition of SiH4 and O2 with concurrent sputtering of erbium is investigated. The Si:O ratio was varied from 3:1 to 1:2 and the annealing temperature was varied from 500 to 900 °C. The most intense Er3+ luminescence is observed from the sample with Si:O ratio of 1:1.2 after 900 °C anneal and formation of silicon nanoclusters embedded in SiO2 matrix. High active erbium fraction, efficient excitation via carriers, and high luminescence efficiency due to high quality SiO2 matrix are identified as key factors in producing the intense Er3+ luminescence.

Time-resolved photoluminescence spectroscopy of Er-implanted porous silicon

We have investigated the time evolution of the 1.54 μm Er 3+ photoluminescence (PL) intensity of Er-implanted porous silicon in the temperature range from 15 to 375 K. Er was implanted into porous silicon with a dose of 1 × 10 15 Er/cm 2 at 380 keV and annealed at 605 °C for 30 min. Upon optical excitation at 488 nm, erbium ions are excited by photo-generated carriers and an intense 1.54 μm PL is observed at room temperature. We have compared the time evolution of the 4I 13 2 → 4I 15 2 transition of Er 3+ to a double-exponential decay. The analysis suggests the existence of two classes of Er sites in porous silicon. This is supported by a study of the Er 3+ PL decay time as a function of excitation pulse width. The characteristic Er 3+ lifetimes in the two sites are 145 μs and 1.37 ms, respectively. In the temperature range from 15 to 150 K, the back transfer of energy from the excited erbium level 4I 13 2 to the host plays the dominant role in the thermal quenching of the Er 3+ luminescence. At temperatures above 150 K, the reduction in Er 3+ PL can mainly be ascribed to thermalization of bound electrons to the conduction band. We have compared the observed Er 3+ PL intensity with the result from a theoretical model and a good agreement is obtained.

2.70 μm CrEr: YSGG laser with high output energy and FTIR-Q-switch

We report on efficient operation of a flashlamp pumped CrEr: YSGG laser at the wavelength of 2.70 μm. A free running output pulse energy of more than 0.6 J at a slope efficiency of 0.36% has been achieved by using a specially-designed low-loss dispersive resonator. We will also report on efficient frustrated total internal reflection (FTIR) Q-switching of this laser. The wavelength of 2.70 μm is of particular interest for laser surgery because of its considerably better transmittance in fused silica fibers compared to well developed 2.79 μm CrEr: YSGG and 2.94 μm Er: YAG lasers.

Excitation Properties of Er-Doped GaP from Photoluminescence and High Pressure Studies

AbstractThe photoluminescence properties of MOCVD GaP:Er were investigated as a function of temperature, applied hydrostatic pressure, and excitation wavelength. Four sharp peaks are observed on the high energy side of the 1.54 μm Er3+ emission. These peaks are selectively excited by below-gap energies and have a significantly shorter lifetime than the main Er3+ emission, suggesting that at least two distinct Er3+ centers contribute to the luminescence. The low temperature photoluminescence excitation (PLE) spectrum of the 1.54 μm emission was also measured. Strong broad excitation of the Er3+ centers occurs with energies well below the indirect bandgap energy. In fact, the Er3+ emission intensity is significantly stronger when excited with below-gap wavelengths than with above-gap wavelengths. This result has been explained in terms of competition between Er3+ excitation and nonradiative deep level recombination for free carriers under above-gap excitation. With below-gap excitation, carriers are promoted directly into the Er3+ excitation pathway via absorption at an erbium-related trap. At 42 kbar, below-gap excitation is no longer more efficient than above-gap excitation, suggesting that competitive capture of free carriers by deep levels has been reduced.

Characterization of Visible and Infrared (1.54 μm) Luminescence from Er-doped Porous Si

AbstractResults of a photoluminescence excitation (PLE) study of Er-implanted porous Si (Er: PSi) are presented. Erbium was implanted at a dose of 1×1015 Er/cm2 at 380 keV and annealed for 30 minutes at 6507deg;C. We observed a nearly identical PLE intensity behavior from 1.54 μm and visible-emitting Er: PSi. This observation indicates that both visible and infrared photoluminescence (PL) arise from carrier mediated processes, and that the 1.54 μm Er3+ PL is related to the porous Si nanostructures. Measurements of the temperature dependence (15–375K) of Er3+ PL intensity and lifetime are also reported.

Optical activation of Er 3+ in silicon co-implanted with carbon

Erbium (Er) and carbon (C) ions are co-implanted into Czochralski-grown silicon. The photoluminescence (PL) intensity of 1.54 μm Er 3+ emission from Si:Er with C is 2–4 times stronger than that of Si:Er. The PL spectra of Si:Er with C (for doses of 1 × 10 13 and 1 × 10 14 cm −2) are composed of many peaks. These peaks are due to the luminescence from CEr complex centers. The temperature dependence of the Er 3+-related PL shows three quenching processes. Their activation energies are 4, 12 and 140 meV, respectively.

Up-converted energy transfer from Er 3+ to Cr 3+ in LiNbO 3 single crystal fibers

In this paper, site occupations of Er 3+ and Cr 3+ in LiNbO 3 (LNO) single crystal fibers are discussed. A pairing structure of Er-Cr tends to provide a geometric advantage for cooperative processes. Efficient up-converted energy transfer from Er to Cr was observed by pumping the 4I 9 2 state in the near infrared. Downward energy transfer from Cr 3+ to Er 3+ was studied by pumping the 4T 2 state of Cr 3+. The up-converted and the downward energy transfer can be used to develop diode-pumped tunable lasers or to sensitize 1.5 μm Er lasers, respectively.

1.55 µm phase-shifted distributed feedbackfibre laser

The authors report the experimental realisation of a 10 cm long 1.55 µm Er3+-doped DFB fibre laser, with a permanent phase shift incorporated into the fibre grating during writing. Output powers of 1 mW and an optical linewidth of 13 kHz are observed.

Spectroscopic properties and diode pumped 1.6 μm laser performance in Yb-codoped Er: Y 3Al 5O 12 and Er: Y 2SiO 5

In this paper we report to our knowledge for the first time diode pumped room temperature cw laser action around 1.6 μm in Er 3+-doped Y 3Al 5O 12 (YAG) and Y 2SiO 5 (YSO) with Yb 3+-codoping. Results under non optimized doping concentrations show a slight advantage of YAG with respect to the laser efficiency whereas the advantage of YSO is the shorter emission wavelenght (1545 nm) and the possibility of continuous tunability.

Direct experimental evidence for trap-state mediated excitation of Er3+ in silicon

The time evolution of the 1.54 μm Er3+ photoluminescence intensity of Er-doped silicon following a 30 μs excitation pulse is investigated. It is found that at 9 K, the 1.54 μm luminescence from Er3+ continues to increase up to 50 μs after the pulse is terminated, when excess photocarriers no longer exist. This provides the first direct experimental evidence that a state in the forbidden gap of silicon acts as the gateway to the excitation of Er3+. Further analysis indicates recombination of bound excitons to be the most likely excitation mechanism.

Magnetocrystalline anisotropy of Er 2Fe 14B

A rotation-magnetic-alignment method was used to align fine-powdered (< 20 μm) Er 2Fe 14B at room temperature while the easy magnetization direction of Er 2Fe 14B lies in the basal plane. X-ray diffraction was used to check the magnetic alignment. For the first time, the temperature dependence of the anisotropy field of Er 2Fe 14B was measured in a wide temperature range from about 170 to 530 K. The anisotropy field was determined using the SPD technique in a pulsed-field magnetometer from 170 to 320 K ( T SI = 323 K) on a magnetically aligned sample and from 330 to 530 K ( T C = 550 K) on a bulk polycrystal.

Passive Q switching of the Er3+:Y3Al5O12 laser at 1.64 μm

Saturable-absorber Q switching of an erbium-doped Y3Al5O12 (YAG) laser at 1.64 μm using U2+:SrF2 and U2+:CaF2 was demonstrated. The Er:YAG was longitudinally pumped using a free-running 1.534 μm Er:glass laser. Q switched 1.64 μm pulses of 1.7 mJ and 25 ns pulse widths were obtained.

Origin of the 1.54 μm luminescence of erbium-implanted porous silicon

Photoluminescence of erbium-implanted porous silicon is investigated. Room temperature 1.54 μm Er3+ luminescence is observed after annealing. The luminescence spectrum, annealing characteristics, temperature quenching, and the luminescence lifetime suggest that the Er3+ luminescence is mediated by photocarriers in the amorphous silicon matrix in porous silicon, and not related to the presence of the crystal nanograins.

Photoluminescence Properties of Er-Doped Porous Silicon

AbstractWe present a photoluminescence study of erbium implanted into porous silicon (Er:PSi) with two different Si porosities, a) Er:PSi with a purple appearance and b) with a green-yellow appearance. Er was implanted with a dose of 1×1015 Er/cm2 at 380 keV and annealed at 650°C for 30 minutes. Room-temperature 1.54μm Er3+ emission was observed from both samples. The emission from purple Er:PSi was four times stronger than that from green-yellow Er:PSi. In contrast, visible luminescence from green-yellow Er:PSi was found to be stronger than that from purple Er:PSi. Temperature quenching and power dependence was investigated to elucidate the excitation mechanisms of Er3+ in porous silicon. The results support a correlation between nanostructures of porous Si and 1.54 μm Er3+ luminescence.

Quantitative SIMS-analysis of erbium profiles in LiNbO3

Modern fiberoptic communication technology uses light of 1.5 μm wavelength and Er3+ is the laser active ion for this wavelength. Doping of crystalline LiNbO3 (an electrooptical material) with erbium ions permits the fabrication of signal-amplifying electrooptic devices. Novel results of three different approaches have been presented to dope the near surface area of LiNbO3 for its application in planar optoelectronics: erbium indiffusion from the surface, implantation of erbium into LiNbO3 and subsequent annealing schemes, and the homoepitaxial growth of Er-doped LiNbO3 on LiNbO3 single crystalline material by a laser deposition method. These experiments are not only useful for creating integrated optical devices with active amplifying functions, but they are also important examples for fabricating and studying novel thin ferroelectric films. Secondary ion mass spectrometry (SIMS) has been employed as the main analytical tool for quantitative determination of the erbium concentration profiles.

Spectroscopic determination of the figures of merit for 3 μm Er3+ lasers

The main spectroscopic methods used to determine the specific figures of merit for stationary 3 μm Er laser generation are discussed. The detrimental effect of the concentration quenching of the4I9/2 Er level is expressed by a new figure of merit.

Ho3+ Doped 2.84.MU.m Laser Glass for Laser Knives, Sensitized by Yb3+.

The fluorescence properties of the Ho3+5I6→5I7 transition in Yb3+-Ho3+codoped aluminozircofluoride glasses were investigated. The emission wavelength of Ho3+ (5I6→→5I7) at 2.84 μm is almost the same as the vibration oscillation absorption of hydroxyl (OH-1) at 2.89 μm. The emission intensity of Ho3+(5I6→→5I7) transition in Yb3+-Ho3+codopedaluminozirco-fluoride glass is 4.5 times higher than commercial 2.7μm Er3+laser glass. As thelifetime of 5I7 level is longer than 5I6 level, the Nd3+, Eu3+, Pr3+, Sm3+ and Tb3+ were investigatedas deactivator for decreasing the lifetime of 5I7 level. Eu3+and Tb3+ are good candidates for deactivator because they have energy levels which are close to the Ho3+5I7 level todecrease the population of Ho3+5I7 level by energy transfer and have not energy levels whichare close to the Ho3+5I6 level or Yb3+2F5/2 level.

Opto-thermal technique for in-vivo stratum corneum hydration measurement

A new method for measuring stratum corneum hydration in-vivo, using opto-thermal transient emission radiometry with 2.94µm Er : YAG excitation and wavelength selective detection, is described. Results on skin recovery following exogenous hydration, skin stripping with Sellotape and wound healing are presented.

Active and passive Q-switching of a 2.79 μm Er: Cr: YSGG laser

Active and passive Q-switched operation of the Er: Cr: YSGG laser at a wavelenght of λ = 2.79 μm has been achieved using three different shutters. Passive switching was obtained using InAs-layers as saturable absorbers, active switching was performed electrooptically and with the FTIR (frustrated total internal reflection) technique. Single giant pulses with output energies up to 34 mJ and pulse widths of 35 ns at fwhm were achieved. InAs-layers were also used as output mirrors for passive Q-switching. In this way bursts of multiple giant pulses were generated (27 mJ in 9 pulses with pulse widths from 89 to 130 ns at fwhm). The different Q-switches were compared with regard to their applicability to medical surgery.