MITSUBISHI

MITSUBISHI LASER DIODESML4XX2 SERIESFOR OPTICAL INFORMATION SYSTEMSI Far - field patternML4XX2 oscillates in the standard transverse mode(TEoo) regardless of the optical output level. Theyhave a typical emitting area (size of near- fieldpattern) of 2.1 x 0.7 fJ. m'. Fig.7 and Fig.S showtypical far-field radiation patterns in "parallel" and"perpendicular" planes.The full angles at half maximun points (FAHM)are typically 11· and 33·~'5Q'5oFig. 7 Far- field patterns in planeparallel to heterojunctions 81/811Reflected lightV- 5mWv 3mwfrom monitoringphotoiode\IWY ~tlmW-30 o 30Off-axis angle (deg.)Fig. 8 Far- field patterns in planeperpendicular to heterojunctions 8.L'5S:>oOff-axis angle (deg.)II 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.In order to shorten the oscillation delay time. thelaser diode is usually biased close to the thresholdcurrent since the delay time is a time for chargingthe junction up to the threshold current. Figure 9shows a standard response waveform obtained bybiasing ML4XX2 to Ith and applying a square pulsecurrent (top of Fig.9) up to 5mW. A quick responseis obtained with rising and falling times beingO.3ns and O.4ns typical respectively.5lcjFig. 9 Pulse response waveformTime (nsec.)2-22'. . MITSUBISHI..... ELECTRIC