共查询到20条相似文献,搜索用时 62 毫秒
1.
A theoretical model for the amplifiers predicts gain coefficients of around 2 dB per milliwatt of launched pump power, in close agreement with previously reported measurements. The model is also used to determine the optimal pump wavelength λopt that maximizes the amplifier gain. It is shown that the latter is insensitive to pump detuning near λopt=1.48 μm, within a 20 nm range, which indicates that broadband, multimode laser diode pump sources and pumps with narrow linewidths should yield identical gain performance 相似文献
2.
Asonen H. Nappi J. Ovtchinnikov A. Savolainen P. Zhang G. Ries R. Pessa M. 《Photonics Technology Letters, IEEE》1993,5(6):589-591
The authors discuss the fabrication and characteristics of high-power (P CW=430 mW) InGaAs/InGaAsP/InGaP ridge waveguide lasers emitting at λ=0.98 μm, which is the optimum wavelength for pumping erbium-doped fiber amplifiers. In the past, high-power operation of Al-free pump lasers has been limited to 150 mW because of catastrophic optical damage of the mirror facet. This problem has been largely removed by increasing the spot size of the laser with the aid of an improved waveguide design. As a result, Al-free lasers can now achieve a maximum power comparable to the conventional GaAlAs-based pump lasers for λ=0.98 μm 相似文献
3.
A report is presented of the thermal shifts of eleven of the twelve lines from the 4F 3/2 Stark energy levels to the 4I 11/2 energy levels in an Nd:YAG laser for a temperature change from 20-200°C. The thermal shift difference between the Stark sublevels R 1, R 2 in 4F 3/2 is found to be about -0.6±0.6 cm-1/100°C. Within experimental uncertainty, all of the lasing lines either moved to longer wavelength or remained unchanged with increasing temperature 相似文献
4.
Brinkmann R. Baumann I. Dinand M. Sohler W. Suche H. 《Quantum Electronics, IEEE Journal of》1994,30(10):2356-2360
Single-pass and double-pass Er-diffused Z- and X-cut Ti:LiNbO3 waveguide amplifiers, optically pumped at λ p≈1484 nm, have been investigated. With a 48 mm long Z-cut amplifier device, Er-diffusion doped at 1100°C, 6.7 dB (coupled pump power Pp,c=170 mW) and 14.7 dB (Pp,c=90 mW) net small-signal gain have been achieved with a single-pass and a double-pass configuration, respectively, at the signal wavelength λs=1531 nm. A Z-cut sample doped at 1135°C showed a considerably improved behavior. 11.3 dB single-pass net small-signal gain has been obtained (Pp,c=170 mW; sample length 5.7 cm). Theoretical calculations predict gain figures up to 20 dB in single-pass and 40 dB in double-pass Er:Ti:LiNbO3 amplifiers with increased (realistic) lengths of 10 cm 相似文献
5.
The optical power emitted by a monomode GaAlAs laser is filtered with a monochromator. The 1/f noise in the filtered emission is found to be directly dependent on the noncoherent emission, such as S pαP ncm. Here s p is the spectral density of the 1/f fluctuations, P nc is the average noncoherent power, m =3/2 under spontaneous emission, and m =4 in the superradiation and laser regions. Study of the 1/f noise in the optical power in a band centered at the laser wavelength and with variable bandwidth shows three operating regions. (1) LED region (at low currents): the fluctuations with a 1/f spectrum are uncorrelated in wavelength. (2) Superradiation region (at currents close to the threshold): the fluctuations are correlated. (3) Laser region: the 1/f noise apparently is dominated by noncoherent emission within a small optical band around the laser wavelength 相似文献
6.
Morkel P.R. Jedrzejewski K.P. Taylor E.R. Payne D.N. 《Photonics Technology Letters, IEEE》1992,4(6):545-547
A high-power, laser-diode-pumped, Q -switched fiber laser operating at 1.053 μm which is suitable for use in time-multiplexed fiber sensor applications is described. The laser emits >1-kW pulses at 1.053 μm with 2-ns duration at up to 1-kHz repetition rates for an adsorbed pump power of only 22 mW at 810 nm. Tunable Q -switched operation over a 40-nm wavelength range has also been demonstrated 相似文献
7.
Brinkmann R. Dinand M. Baumann I. Harizi C. Sohler W. Suche H. 《Photonics Technology Letters, IEEE》1994,6(4):519-521
The first integrated optical amplifying acoustically tunable wavelength filter in Er-doped LiNbO3 is reported. At the signal wavelength of λs=1531 nm a maximum gain of 4.8 dB has been obtained with a coupled pump power of 160 mW (λp =1484 nm). Lossless signal transmittance has been achieved with a pump power as low as 13.5 mW for λs>1561 nm 相似文献
8.
The observed 1/f noise in the light-output power S p of four different types of heterostructure lasers is explained in terms of spatially uncorrelated gain fluctuations and spontaneous emission fluctuations. Two possible noise sources are suggested: fluctuations in the absorption coefficient and fluctuations in the number of free carriers. Both models are in agreement with the experimental results obtained from index-guided and gain-guided diodes at wavelengths of 1.3 and 0.8 μm. The dependence S p ∝P m has been observed with P the average light-output power and m =3/2 under spontaneous emission, a small transition region with m =5/2, m =4 in the superradiation region, and 0⩽m ⩽1 in the laser region 相似文献
9.
Musa S. van Weerden H.J. Yau T.H. Lambeck P.V. 《Quantum Electronics, IEEE Journal of》2000,36(9):1089-1097
Er-doped Al2O3 thin films have been deposited by reactive co-sputtering onto thermally oxidized Si-wafers. The deposition process has been optimized with respect to the requirements originating from the application of these multilayer structures as integrated optical amplifiers for the third telecom window, i.e., the wavelength range 1.52-1.55 μm. The films obtained at a substrate temperature of only 400°C are amorphous and show a homogenous structure, without columns or grains. For slabguides, background losses smaller than 0.25 dB/cm have been obtained, even without any annealing. A relatively broad luminescence band, having an FWHM of ~55 nm around the 1.533-μm wavelength, has been measured. From gain versus pumping power curves, an upconversion coefficient lower then 20·10-25 m3/s has been derived, being half of the values reported up to now in the literature. Simulations based on experimentally determined material parameters and assuming a channel attenuation of 0.5 dB/cm indicate, for 0.24 at.% Er channel devices with an optimal channel length of 7.7 cm, an amplification of 8 dB at 1.533 μm for a pump wavelength of 1.48 μm, and a pump power of only 8.7 mW 相似文献
10.
The OMDR (optical-microwave double resonance) effect in the Cs D 2 line was studied for realizing a gas-cell-type Cs atomic frequency standard. A glass cell containing Cs with buffer gases (Ar/N2=1.26, total pressure=39 torr) was placed in a TE012 mode microwave cavity at a temperature of 45°C and was pumped using a GaAs semiconductor laser frequency locked to an external interferometer tuned to the 6P3/2 (F=2,3,4)←6 S 1/2(F =3) transition. The OMDR signal appearing at the resonance to the F =4←3 hyperfine transition of the 6S1/2 state shifted with detuning of the laser frequency and with change of the laser and microwave powers. The dependence of the shift on these variables around an optimum operating condition was obtained as, ΔνMW[Hz]=-(0.31±0.02) {1+(0.44±0.15) (ΔP L/P L)} ΔνL [MHz]-10(ΔV MW/V MW) 相似文献
11.
Expressions are obtained for specifying the optimal error probability (minimum P e) thresholds λ01 and λ02 for the traditional and modified sign detectors, respectively. These thresholds are shown to depend on the parameters p , P 1, and M where: M is the number of observations z i used in the test statistic; P 1=P (H 1 ) is the prior probability for hypothesis H 1 that signal s 1 is present and 1-P 1 =P (H 0) corresponds to the hypothesis H 0 that signal s 0 is present; and p =Pr{z i⩾0|H 1} with s 0=0 for the traditional sign detector and p =Pr{z i⩾λ|H 1 }=Pr{z i<λ|H 0} with λ =(s 0+s 1)/2 for the modified sign detector. The expressions for λ01 and λ02, are given explicitly, and shown to be independent of P 1 for sufficiently large M . Optimal P e versus M performance curves, corresponding to both versions of the sign detector, are obtained for a representative range of values for p and P 1 相似文献
12.
Kudo K. Miyake Y. Hirayama H. Tamura S. Arai S. Suematsu Y. 《Photonics Technology Letters, IEEE》1992,4(10):1089-1092
A room temperature CW operation of Ga0.3In0.7As/GaInAsP/InP GRINSCH compressive strained MQW lasers with 30~60 nm wide wire active region was achieved. This device was fabricated by two-step LP-OMVPE growths on p-type InP substrate and wet chemical etching. Threshold current as low as 53 mA ( L =910 μm, J th=2.9 kA/cm2) was obtained at RT-CW condition. The spontaneous emission peak and the lasing wavelength of strained MQW wire lasers exhibited approximately 20-meV blue shift from those of MQW film lasers cut out from the same wafer 相似文献
13.
Energy transfer from selectively formed metastable states of SiO is used to pump sodium-atom laser amplifiers at λ≈569 nm (4d 2D -3p 2P ), λ≈616 nm (5s 2S -3p 2 P ), and λ≈819 nm (3d 2D -3p 2P ). The a 3Σ+ and b 3Π states of SiO are generated in high yield from the Si+N2O→SiO+N2 reaction. The energy stored in the triplet states is transferred in a highly efficient collisional process to pump sodium atoms to their lowest excited 3d 2 D , 4d 2D , and 5s 2S states. Adopting a sequence in which high concentrations of silicon and sodium atoms are mixed and oxidized, a continuous amplification (gain condition) is monitored which suggests the creation of a population inversion among the receptor sodium-atom energy levels and forms the basis for full cavity oscillation on the Na4 d 2D -3p 2P transition at 569 nm 相似文献
14.
Reports a theory for calculating the coupling length L c of Ti:LiNbO3 single-mode waveguide directional couplers from process parameters and operating wavelength. Estimates are accurate to within a factor of 2 compared with published experimental results for z -cut y -propagating LiNbO3 devices for 0.63 μm⩽λ⩽1.56 μm. Use of this formalism to assess acceptable process parameter and wavelength tolerances is demonstrated 相似文献
15.
Local fractional population measurement of the upper state 4I 13/2 of an erbium-doped fiber amplifier
A method of measuring the local fractional population of the upper state 4I 13/2 of an erbium-doped amplifier is investigated. The local fractional population is related theoretically by EDF parameters to the local spontaneous emission (SE) power that leaks laterally from the EDF. The proportional constant between the fractional population and the detected SE power is determined experimentally by measuring saturated spontaneous emission power. The local fractional population of a 19.7 m-long EDF, pumped with a 1.48 μm light and injected with a 1.552 μm signal light, was measured by detecting the local SE power with a Ge photodiode having a diameter of 2 mm. The measured fractional population coincides with the calculated value 相似文献
16.
The OMDR (optical-microwave double resonance) spectrum of 87 Rb with the aim of using a frequency-stabilized GaAs semiconductor laser instead of an Rb lamp as a pumping source in a gas-cell-type Rb frequency standard. Natural isotope 87Rb was sealed in a glass cell with buffer gases (Ar/N 2=1.2, total pressure=39 torr). The double resonance signal in the 5P 1/2(F =2)←5S 1/2( F =1) transition appearing at the resonance to the F =2←1 hyperfine transition of the 5S 1/2 state was detected. The optimum operational cell temperature was 56°C. The peak-to-peak frequency width of the atomic hyperfine resonance discriminator used to stabilize the microwave frequency shifts induced by detuning of the laser frequency, changes in the laser and microwave powers, and temperature drift of the cell were investigated 相似文献
17.
Gokhale M.R. Wei J. Studenkov P.V. Wang H. Forrest S.R. 《Photonics Technology Letters, IEEE》1999,11(8):952-954
We demonstrate high-performance InGaAsPN quantum well based long-wavelength lasers grown on GaAs substrates, nitrogen containing lasers emitting in the λ=1.2- to 1.3-μm wavelength range were grown by gas source molecular beam epitaxy using a RF plasma nitrogen source. Under pulsed excitation, lasers emitting at λ=1.295 μm exhibited a record low threshold current density (JTH) of 2. 5 kA/cm2. Lasers grown with less nitrogen in the quantum well exhibited significantly lower threshold current densities of JTH =1.9 kA/cm2 at λ=1.27 μm and JTH=1.27 kA/cm2 at λ=1.2 μm. We also report a slope efficiency of 0.4 W/A and an output power of 450 mW under pulsed operation for nitrogen containing lasers emitting at 1.2 μm 相似文献
18.
A nonlinear model for a travelling-wave semiconductor optical amplifier has been used to determine eye closure degradations for 2.4 and 10 Gb/s NRZ/RZ lightwave systems due to gain saturation effects in the optical amplifier. At 10 Gb/s, with a carrier lifetime of 300 ps, the results indicate that the penalty is less than 1 dB for both NRZ and RZ systems provided that the ratio of the input power (P in ) to the saturation output power (P sat) is less than -17 dB. The NRZ system penalty is slightly larger than the RZ penalty when P in/P sat is larger than -17 dB. For example, with P in/P sat=-10 dB, the NRZ system penalty is about 2.8 dB versus 2 dB for the RZ system. The system penalty at 2.4 Gb/s is slightly less than that at 10 Gb/s. At P in/P sat=-10 dB, the NRZ system penalty is about 2.5 dB versus 1.5 dB for RZ 相似文献
19.
Jian Wei Fengnian Xia Chunqiang Li Forrest S.R. 《Photonics Technology Letters, IEEE》2002,14(5):597-599
We demonstrate high performance, λ=1.3- and 1.4-μm wavelength InGaAsN-GaAs-InGaP quantum-well (QW) lasers grown lattice-matched to GaAs substrates by gas source molecular beam epitaxy (GSMBE) using a solid As source. Threshold current densities of 1.15 and 1.85 kA/cm2 at λ=1.3 and 1.4 μm, respectively, were obtained for the lasers with a 7-μm ridge width and a 3-mm-long cavity. Internal quantum efficiencies of 82% and 52% were obtained for λ=1.3 and 1.4 μm emission, respectively, indicating that nonradiative processes are significantly reduced in the quantum well at λ=1.3 μm due to reduced N-H complex formation. These Fabry-Perot lasers also show high characteristic temperatures of T0 =122 K and 100 K at λ=1.3 and 1.4 μm, respectively, as well as a low emission wavelength temperature dependence of (0.39±0.01) nm/°C over a temperature range of from 10°C to 60°C 相似文献
20.
An In0.41Al0.59As/n+-In0.65 Ga0.35As HFET on InP was designed and fabricated, using the following methodology to enhance device breakdown: a quantum-well channel to introduce electron quantization and increase the effective channel bandgap, a strained In0.41Al0.59As insulator, and the elimination of parasitic mesa-sidewall gate leakage. The In0.65Ga0.35As channel is optimally doped to N D=6×1018 cm-3. The resulting device (L g=1.9 μm, W g =200 μm) has f t=14.9 GHz, f max in the range of 85 to 101 GHz, MSG=17.6 dB at 12 GHz V B=12.8 V, and I D(max)=302 mA/mm. This structure offers the promise of high-voltage applications at high frequencies on InP 相似文献