Superluminescent diodes with output power over 1 W and with diffraction-limited beam quality

2005ConferenceonLasers and

Electro-Optics Europe

Superluminescent

diodes with output

power

over

1 W and with

diffraction-limited

beam

quality

Chih-HungTsaia, Yi-Shin SUa, andChing-Fuh Lin' b

aInstituteofElectro-Optical Engineering,NationalTaiwvanUniversity, Taipei, Taiwan,R OC.

bDepartment ofElectricalEngineeringand InstituteofElectronicsEngineering,National TaiwanUniversity, Taipei,

Taiwvan,R.O.C.

Tel: 886-2-23635251-405Fax: 886-2-23677467 Email:cflin(adcc.ee.ntu.edu.tsv

High power and good beam quality are desired for broadband

semiconductor lightsources in many applications. We designedanewtype 100um

of broadareasuperluminescence lightsourcethatiscapableofemitting 1.4

watt output with diffraction limited far field divergence. Without any AR

coating, the emitted spectrum has20nmFWHM and free ofthemodulation 1000um

causedby FabryPerot modes. \

Thedesigned waveguide pattern is showninFig. 1. The waveguide is tiltedatanangle from the facet normal.Thetileangleis 60. Inaddition,two

triangular parts are cut awayfrom the waveguide,as shown in Fig. 1. The 1

emitting aperture of this device is 100um in width, and the total device 480um 1960um

length is 1960um. The active layer is designed for 1310nm wavelength

grownonthe InP substrate.

Fig. 2 is the L-Icurveof this device.TheL-1curveof this diode hasa

threshold-like behavior at lAmp. Below the threshold, only 3mW output 480um

poweris observed. Above thisthreshold,theoutputpower increaselinearly ,

withcurrent. The slope efficiency is 0.15W/A. The measuredoutputpower 600um

can achieve 1.4Wperfacet when thecurrent is 12Amp. However,spectrum

observation shows that this device has no oscillation modes. With 6Amp Fig. 1 Wavegude Design

injectioncurrent, themeasuredspectrumhas20nm FWHM,asshown in Fig.

3. The spectrum profile is smooth and no F.P. mode is observed. Thus, this device is not a laser diode but a super

luminescence diode.

Thefar fieldpatternofthis device is measured. Thelight emitted from the device isat32°awayfrom the direction

of facet normalatthesamesideasthetilted direction of thewaveguide. The FWHM of the far field is 20. The measured

nearfieldpatternhas43,um FWHMatthesamecurrentof 6 Amp. Thefarfield divergence is equaltothediffraction limit angle of thenearfield distribution.

I ,; 09:33:32 MAR 9, 20f4 RIL 28.0 PW MKR *l WulL 1303.0 no 1400 1200 1000 E 800 ) 600 C 400 200 0 0- _g .I-

.-.~~~~~-

11

w _

== XI=

I

_-j

I?

_{Jiaa__n}

,

_

U 2 4 6 d 1U 12 STAR 12 . nu SIUTP 1350.1d n *RB Inm VB2 Hz S -ST30 sec Current(A)

Figure

2

L-I

curve

Figure

3 Emission

Spectrum

at 6

Amp

with20nm FWHM

References:

1. C. Smudzinski,D.Botez, L. J.Mawst,A.Bhattacharya,M.Nesnidal,and R.F.

Nabiev,

"Three-corearrow-typediode laser,novelhigh-power, single-modedevice, and effective master oscillator for flared antiguided MOPAs," IEEE J. Select.Topics Quant. Electron, vol. 1,

pp.129-137,

1995.

2. S. D.deMars, K. M.Dzurko,R. J.Lang, D. F.Welch, D. R. Scifres, and A. Hardy, "Angled grating

distributed-feedback laser with IWsingle-mode, diffraction-limited output at 980nm," Techn. Digest CLEO 96, pp.77-78, 1996.