摘要:

Experimental observations of the lasing spectrum of a single mode semiconductor laser under continuous microwave modulation reveal that the lasing spectrum is apparently locked to a single longitudinal mode for optical modulation depths up to ∼80%, beyond which the lasing spectrum becomes multimoded, whose envelope width increases very rapidly with further increase in modulation depth. These results are satisfactorily explained by a theoretical treatment which enables one to predict the dynamic lasing spectrum of a laser from its cw lasing spectra at various output powers.

ISSN:0003-6951    

DOI:10.1063/1.94463

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The spectra and relative efficiency of200Hg 79Br, Hg 79Br, and HgBr in a small UV preionized electric discharge laser have been measured. There is a similar improvement in laser energy for both isotopic samples compared to the natural abundance mixture which can be attributed to a narrower gain spectrum and consequent higher peak gain. At the highest output measured, the increase in laser energy was about 25%. We estimate this is due to roughly 15% increase in small‐signal gain.

ISSN:0003-6951    

DOI:10.1063/1.94464

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Transient stimulated Raman scattering of amplified pulses from a passively mode‐locked ring cw dye laser has been demonstrated to be a useful method for the production of coherent near infrared femtosecond light pulses. Hypershort Stokes radiation is generated in capillary waveguides containing high pressure hydrogen (830 nm, 1265 nm) and methane (752 nm, 964 nm, 1340 nm) and pulse shortening factors as large as 2.9 have been observed.

ISSN:0003-6951    

DOI:10.1063/1.94465

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We report combined active and passive mode locking of an external cavity semiconductor laser containing one absorbing and one gain diode. Compared with active mode locking alone this method requires less critical tuning of the rf modulation frequency and is not limited to operation close to threshold. Colliding pulse mode locking is achieved by placing the absorber diode at one end of the cavity so as to increase the effective absorber cross section. Streak camera measurements show that the pulse trains are free from background noise and that the 30‐ps pulses are bandwidth limited with sech2profiles.

ISSN:0003-6951    

DOI:10.1063/1.94466

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The fundamental, quantum phase noise limited Lorentzian linewidth was directly measured from the beat‐note spectra generated by heterodyning PbS1−xSexdiode lasers with a stable CO gas laser. The experimental results were matched by calculated theoretical line profiles. Linewidths as narrow as 22 kHz full width at half‐maximum power were observed.

ISSN:0003-6951    

DOI:10.1063/1.94467

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Picosecond photoconductors in the form of dielectric resonators have been used to generate and detect extremely short bursts of millimeter wave radiation at 55 GHz with a repetition rate of 100 MHz. Both the generator and detector are tuned to a frequency which is determined by the length of the photoconducting dielectric resonators. The detector, which is phase coherent, has an estimated noise equivalent power of only 4×10−11W for an integration bandwidth of 1 Hz, and is capable of resolving time intervals corresponding to a small fraction of one millimeter‐wave cycle.

ISSN:0003-6951    

DOI:10.1063/1.94468

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Purely optical remote monitoring of low‐level CH4gas is realized for the first time by the method employing a 2‐km long‐distance, low‐loss silica optical fiber link and a compact absorption cell in conjunction with a high radiant InGaAsP light‐emitting diode (LED) at 1.33 &mgr;m. Based on the present experiment, the detection limit of CH4in air was confirmed to be approximately 2000 ppm, i.e., 4% of the lower explosion limit of CH4. This result supports the conclusion that the fully optical remote sensing system incorporating ultralow loss optical fiber networks and near infrared LEDs or laser diodes can be extensively used for the detection and surveillance of various inflammable and/or explosive gases in industrial and mining complexes as well as in residential areas.

ISSN:0003-6951    

DOI:10.1063/1.94469

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The effect of strongly magnetized electrons on the spectrum of collective electron density fluctuations was observed for the first time in a laboratory plasma. A single mode CO2laser and coherent detection were used to scatter from a hydrogen plasma with the scattering wave vector perpendicular to the magnetic field. The results demonstrate that both the ion temperature and direction of the magnetic field can be measured simultaneously.

ISSN:0003-6951    

DOI:10.1063/1.94452

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The field‐ion microscope technique has been employed to determine directly a radiation damage profile, with atomic resolution, in a platinum specimen which had been irradiated at 60 K with 20‐keV Kr+ions to a fluence of 5×1012cm−2. It is shown that the microscopic spatial vacancy distribution (radiation damage profile) is directly related to the elastically deposited energy profile. The experimentally constructed radiation damage profile is compared with a theoretical damage profile—calculated employing the transport of ions in matter (TRIM) Monte Carlo code—and excellent agreement is obtained between the two. Thus, it is demonstrated that it is possible to go directly from a microscopic spatial distribution of vacancies to a continuous radiation damage profile.

ISSN:0003-6951    

DOI:10.1063/1.94453

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A photoelectrochemical method has been developed for etching integral lenses on light‐emitting diodes (LED’s). An LED wafer is immersed in an electrolyte and biased at a potential at which the etch rate is directly proportional to light intensity. The image of a photomask is projected onto the surface of the wafer to produce a spatial variation of light intensity to etch the desired shape. The method has been used to etch spherical lenses on then‐InP substrates of InGaAsP/InP LED’s. Extremely smooth surfaces are obtained for etch rates ≲0.5 &mgr;m/min. The resulting lensed LED’s gave the theoretically expected improvement in the light coupled into an optical fiber, indicating that the scattering loss of the lenses was very small. The technique is compatible with the standard LED processing and the apparatus required is relatively simple.

ISSN:0003-6951    

DOI:10.1063/1.94461

出版商:AIP    

年代:1983

数据来源: AIP