摘要:

Vertical coupling of light output from a stripe InGaAsP/InP laser amplifier to the bottom of the substrate for detection by means of a 45° mirror has been demonstrated. The composite‐cavity amplifier structure is shown to have an inherent low facet reflectivity and unidirectional amplification property. With a fiber‐to‐detector gain of 15.4 dB and a nearly diffraction‐limited output spot size, the device is suitable for compact integration with a photodetector as an optical pre‐amplifier in a high bit‐rate direct detection system.

ISSN:0003-6951    

DOI:10.1063/1.105537

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

An eight‐channel single‐mode wavelength division demultiplexer operating at 740, 750, 760, 770, 780, 790, 800, and 810 nm with diffraction angle varying from 16° to 44° and using a graded index (GRIN) polymer waveguide is reported for the first time. Diffraction efficiency up to 55% was measured. The wavelength spreading of the Ti:Al2O3laser (∼4 nm, 3 dB bandwidth) causes an average crosstalk figure of −15.8 dB. The beamwidth of the diffracted signal as a function of the input beamwidth, the grating interaction length, and the diffraction angle are considered. Occurrence of the maximum value is further discussed. A waveguide lens is needed to efficiently couple the diffracted light into an output fiber whenever the diffracted beam size is beyond the core diameter of the fiber involved.

ISSN:0003-6951    

DOI:10.1063/1.105538

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A modulation bandwidth approaching 5 GHz in a GaAs quantum well vertical cavity surface emitting laser with a mushroom mesa structure is reported. The modulation speed and the maximum power of 1.5 mW were limited by device heating. The second harmonic distortion as a function of frequency was measured at an injection current twice threshold and an optical modulation index of 10%, and a peak distortion of about −25 dBc was obtained.

ISSN:0003-6951    

DOI:10.1063/1.105539

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A residue which is characteristic of internal scattering is extracted from the below threshold spectra of 1.3 &mgr;m semiconductor diode lasers by fitting a smooth function to the measured gain profile. The residue is found to be correlated with the above threshold spectral output. This suggests that the amount of scattering in the active region is an important quantity in determining the spectral output of semiconductor diode lasers.

ISSN:0003-6951    

DOI:10.1063/1.105540

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

High‐mode‐volume, good optical quality laser beams of 55 mJ, of 19 ns duration and with a brightness of 3×1013W cm−2Sr−1, have been extracted from a high‐gain, short‐pulse XeCl laser, with an unstable resonator using a super‐Gaussian reflectivity mirror. The misalignment angle of the output coupler to decrease the normalized output energy by 20% was 3.5 mrad.

ISSN:0003-6951    

DOI:10.1063/1.106391

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The conversion of laser phase noise to intensity fluctuation noise in optical fibers due to mixing with Rayleigh scattered light is considered. A theory combining the laser quantum phase dynamics and the statistical scattering in the fiber leads to simple expressions for the spectral densities of the intensity fluctuations in a number of generic cases. These are compared with experiments involving distributed feedback semiconductor lasers and low‐loss fibers with lengths up to 20 km.

ISSN:0003-6951    

DOI:10.1063/1.105541

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report the use of electro‐optic sampling techniques in the measurement of the electro‐optic frequency response of a poled organic layer, to 20 GHz. The organic material tested was a Disperse Red 1/poly(cyclohexyl methacrylate) guest/host system which was deposited and poled on top of a GaAs based coplanar waveguide transmission line. The GaAs substrate also served as the reference electro‐optic material in the hybrid structure, which was optically sampled from both sides.

ISSN:0003-6951    

DOI:10.1063/1.105542

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A theoretical model that uses simple, analytic valence band equations to calculate the differential gain in strained layer InGaAs/GaAs quantum wells shows good agreement with experimental differential gain values obtained from multiple quantum well strained layer lasers. The differential gain in these devices is 7 times greater than in bulk,p‐type doped InGaAsP lasers. Calculations including nonlinear damping effects indicate that modulation bandwidths exceeding 60 GHz should be achievable in strained layer quantum well lasers.

ISSN:0003-6951    

DOI:10.1063/1.105543

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Gain‐guided Ga0.84In0.16As0.14Sb0.86/Al0.75Ga0.25As0.06Sb0.94double‐heterostructure lasers emitting at ∼2.2 &mgr;m have been operated cw at heat sink temperatures up to 30 °C. The maximum output powers obtained at 5 and 20 °C were 10.5 and 4.6 mW/facet, respectively. For pulsed operation of broad‐stripe lasers 300 &mgr;m wide and 1000 &mgr;m long, the threshold current density was as low as 940 A/cm2, the lowest room‐temperature value reported for diode lasers emitting beyond 2 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.105544

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A number of authors have observed, by using light scattering from a laser beam, contamination particles suspended in an rf process plasma. The region of space occupied by the particles appears finite, e.g., a ring; there is experimental evidence that the particles are negatively charged. We show, by using a tuned Langmuir probe, that the trap is electrostatic in nature. The volume of a trap is as much as 5 V larger in electrostatic potential than the surrounding plasma. This means that the volume of the trap is positively charged with the electric field being directed outward from the trap. Thus, negatively charged particles will flow into it. The electrostatic potential rises so rapidly at a trap boundary that a double layer may exist there. Finally, the plasma‐sheath interface is found to follow the topographic contour of the rf electrode surface.  

ISSN:0003-6951    

DOI:10.1063/1.105545

出版商:AIP    

年代:1991

数据来源: AIP