摘要:

High temperature and very low threshold current operation of a separate confinement heterostructure (SCH) AlGaInP/GaxIn1−xP (x=0.43) strained multiple quantum well (SMQW) lasers has been achieved. Continuous wave (cw) operation was observed up to at least 150 °C with an output power of more than 7 mW, which is the highest cw operating temperature ever reported for devices operating in the visible wavelength region. The characteristic temperature between 20 and 80 °C was 130 K. The threshold current and threshold current density at 25 °C were 13.9 mA for a 5×160 &mgr;m device and 430 A/cm2for a 80×770 &mgr;m device.

ISSN:0003-6951    

DOI:10.1063/1.105723

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Planar optical waveguides in single crystals of KNbO3were produced by 1 and 2 MeV He ion implantation with doses between 5×1013and 5×1014cm−2. We observe nonleaky waveguiding due to an implantation induced increase ofnc, the smallest of the three refractive indices of KNbO3. For 2 MeV He ions and a dose of 1014cm−2waveguides with typical propagation losses of ∼3 dB/cm have been fabricated. The possibility of producing nonleaky waveguides by ultralow dose implantation promises the creation of complicated channel waveguide structures within minutes.

ISSN:0003-6951    

DOI:10.1063/1.105724

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Subpicosecond electromagnetic pulses having THz bandwidths have been generated from large aperture Sip‐i‐ndiodes under different biases by illumination with fs‐optical pulses. The amplitude and spectral bandwidth of the radiated pulses increases with the reverse bias on thep‐i‐ndiode. This effect can be explained by the electric field dependence of the transient drift velocity of the photo‐generated carriers in the intrinsic region of thep‐i‐ndiode.

ISSN:0003-6951    

DOI:10.1063/1.105725

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report continuous‐wave room‐temperature operation of a semiconductor ring resonator diode laser with a singleY‐junction outcoupling waveguide. This device with a 150 &mgr;m radius and 8‐&mgr;m‐wide etched‐rib waveguide has a threshold current of 72 mA and emits up to 1 mW of single‐frequency output. The side‐mode‐rejection ratio of this laser exceeds 22 dBm over a ≳50 mA current range corresponding to a stable operating mode of the laser. Studies of the emission behavior in this and other similar ring lasers suggest that the ring is lasing in ‘‘whispering gallery’’ modes, and also that theYjunction is affecting mode selection in the ring.

ISSN:0003-6951    

DOI:10.1063/1.105730

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

In this letter, an rf‐excited, anodized aluminum structure waveguide CO2laser is presented, which has the advantages of low cost, better cooling, and ease of manufacture. With this structure, we have obtained 12 W EH11waveguide mode output power from only a 300 mm gain length.

ISSN:0003-6951    

DOI:10.1063/1.105701

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report the first observation of the photorefractive effect in cadmium sulfide at low optical power. The maximum gain coefficient measured with no applied field at 633 nm is 0.3 cm−1. The response time scales sublinearly with intensity and is independent of grating spacing. At a maximum intensity of 80 mW/cm2, a response time of 0.9 ms is obtained. The photorefractive sensitivity is the largest among photorefractive material operating in the visible range.

ISSN:0003-6951    

DOI:10.1063/1.105702

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have carried outinsitutransient absorption and fluorescence spectroscopy measurements in two ‘‘wet’’(OH content ∼0.1%) fused silica samples (Suprasil II from Heraeus Amersil and P‐30 from Shin‐Etsu Quartz Product) during KrF laser irradiation. Both samples exhibit an absorption peak at 210 nm corresponding to theE’center. For Suprasil II, there is also a 265 nm absorption peak, and both peaks increase with the number of irradiated pulses showing little relaxation after the laser was turned off. The region irradiated with three million pulses at 400 mJ/cm2fluence ten months ago has a residual absorption of about 10%/cm at 210 nm. On the other hand, the P‐30 shows a rapid increase in the 210 nm absorption in both the unirradiated and previously irradiated regions during the initial irradiation and levels off after a few thousand pulses. There is no residual absorption at the spot irradiated for 63 million pulses ten months ago. However, the initial rate of increase in the previously irradiated spot is twice as high as compared to the unirradiated spot. This suggests the density of the precursor state for theE’center is higher in the previously irradiated region. The fluorescence intensity at 650 nm increases with the induced absorption for Suprasil II, but is almost independent of the number of irradiation pulses in P‐30. The quasilinear repetition‐rate dependence suggests the fluorescence is transient in nature and relaxes partially between successive laser pulses.

ISSN:0003-6951    

DOI:10.1063/1.105703

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A comprehensive timing jitter comparison is made for mode‐locked semiconductor lasers using active, passive, and hybrid mode‐locking techniques in both external and monolithic cavity configurations. Active mode locking gives the lowest residual rms timing jitter of 65 fs (150 Hz‐50 MHz), followed by the hybrid and passive mode‐locking techniques. It is found that monolithic cavity devices with all active waveguides have higher timing jitter levels than the comparable external cavity case.

ISSN:0003-6951    

DOI:10.1063/1.105704

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Novel laterally injected lasers were fabricated by impurity‐induced disordering (IID). The laterally injected IID (LID) lasers have a self‐aligned structure and planar configuration; its processing procedures are almost identical to that used for our recently reported vertically injected IID lasers, and are considerably simpler than those of any other laterally injected laser yet reported. The LID lasers have a minimum threshold currentIth=3.2 mA (typicalIth=4 mA) and a maximum light output 11 mW, with a differential quantum efficiency &eegr;d=32% per facet under room‐temperature continuous‐wave operation. The LID lasers can also be injected vertically by deliberately using ann+‐doped (instead of semi‐insulating) GaAs substrate and making additional ohmic contacts on the bottom surface of the wafer. A number of interesting aspects about the LID lasers were revealed by comparing theL‐Icharacteristics of the laser under different injection modes, and by studying theI‐Vcharacteristics of different combinations of the top and bottom ohmic contacts.

ISSN:0003-6951    

DOI:10.1063/1.105679

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report nonlinear absorption around theZ3exciton in CuCl microcrystallites embedded in a glass matrix. Our experiments are performed in a test‐pump configuration with picosecond pulses at low temperature. In addition to a shift and a bleaching of the excitonic resonance, induced absorption on the high‐energy side is found. The nonlinear index changes induced per exciton per unit volume of CuCl quantum dot could be determined by Kramers–Kronig transformations.

ISSN:0003-6951    

DOI:10.1063/1.105680

出版商:AIP    

年代:1991

数据来源: AIP