MITSUBISHI

MITSUBISHI LASER DIODESML4XX2A SERIESFOR OPTICAL INFORMATION SYSTEMSI Far-field patternML4XX2A oscillates in the standard transversemode (TEoo) regardless of the optical output level.They have a typical emitting area (size of near-fieldpattern) of 2.1 f.l rn'. Fig.7 and Fig.8 show typical far-fieldradiation patterns in "parallel" and ·perpendicular"planes.The full angles at half maximum points (FAHM)are typically 11 0 and 33 0 •~Co "'5oFig. 7 Far- field patternsin plane parallel to heterojunctions 81/8 IIReflected lightlmW30Off- axis angle (deg.)Fig. 8 Far- field patternsin plane perpendicular to heterojunctions 8.loC.Co "'5oOff - axis angle (deg.)iii Pulse response waveformIn the digital optical transmission systems. theresponse waveform and speed of the light outputagainst the input current pulse waveform is one ofthe main concerns.Generally. the laser diode is biased up to near thethreshold current to minimize oscillation delay time.Figure 9 shows a standard response waveformobtained by biasing ML4XX2A to Ith and applyinga square pulse current (top of Fig.9) up· to 3mW.The rise time and the fall time in Fig.9 are typicallyO.3ns and O.4ns. They are limited by responsespeed of the detecter.21c:oCo~Fig. 9 Pulse response waveformTime (nsec.)InpUj pulse• MITSUBISHI;"ELECTRIC2 -29