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Submitted on 1 Jan 1988
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FABRICATION AND LASING PROPERTIES OF A NOVEL SINGLE LONGITUDINAL MODE 1.5 µm GaInAsP/InP DISTRIBUTED REFLECTOR (DR)
LASER
K. Komori, H. Suzuki, K. Lee, S. Arai, Y. Suematsu, M. Aoki, S. Pellegrino
To cite this version:
K. Komori, H. Suzuki, K. Lee, S. Arai, Y. Suematsu, et al.. FABRICATION AND LASING PROP- ERTIES OF A NOVEL SINGLE LONGITUDINAL MODE 1.5 µm GaInAsP/InP DISTRIBUTED REFLECTOR (DR) LASER. Journal de Physique Colloques, 1988, 49 (C4), pp.C4-341-C4-343.
�10.1051/jphyscol:1988472�. �jpa-00227970�
JOURNAL DE PHYSIQUE
Colloque C4, suppl6ment au no9, T o m e 49, septembre 1988
FABRICATION AND LASING PROPERTIES OF A NOVEL SINGLE LONGITUDINAL MODE 1.5 pm GaInAsP/InP DISTRIBUTED REFLECTOR (DR) LASER
K. KOMORI, H. SUZUKI, K.S. LEE, S. ARAI, Y. SUEMATSU, M. AOKI and
s .
PELLEGRINO*Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-Ku, Tokyo 152, Japan
*c.s.EL.T., Centro Studi e Laboratori Telecomunicazioni SPA, Via Reiss Romoli 274, I-10148 Torino, Italy
Resume
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Un nouveau laser, du type Q single mode dynamique, avec reflecteur distribue dans les regiones active et passive a Bt& realis6. On a identifie des int6rSssantes proprietes comme un eleve rapport de soppression des modes satellites, un petit courrant de seuil et des proprietes dt6mission asymmetrique.Abstract
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A new type of dynamic single mode laser, which has distributed reflector (DR) both in active and passive regions has been realized; attractive properties such as high sub-mode suppression ratio, low threshold and asymmetric properties have been detected.Introduction
We report the fabrication process and preliminary results concerning a new dynamic single longitudinal mode (DSM) laser with the aim of high power operation and high single mode fabrication yield. Asymmetric DFB lasers in High/Low reflection configuration reported up to now and obtained by coating front and rear facets, have a DSM expectation value around 80% (1). Hence we developed a structure capable of high power, high yield DSM operation as well as suitable for monolithic integration, by joining a Distributed Bragg reflector to a DFB structure, in a Bundle Integrated Guide (BIG) (2) configuration to maximize
the coupling between DFB and DRB regions. The theoretical analysis of the structure has been published elsewhere (3).
Structure and Fabrication
A schematic drawing of the structure is shown in fig.1, and in fig.2 the fabrication sequence is outlined. The island-type mesa process (4) was employed, during the second within the four total LPE growth, in order to obtain flat growth conditions of the
GaInAsP (Agd.3 urn) passive waveguide. High quality first order grating on AZ photoresist /
has been obtained employing an Ashing process at low oxygen pressure and RF power;the Ashing rate is shown in fig.3. The grating was transcripted using (HBr:HN03:H20=1:1:10) solution:
the chemical characterization of the system and its etching properties will be described elsewhere. Finally, usual Buried Heterostructure was formed during the fourth LPE growth.
Results --
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1988472
C4-342 JOURNAL
DE
PHYSIQUEMinimum CW threshold current of 25 mA was obtained for a 400 um DFB, 200 um DBR regions length, respectively. Since the stripe width was 3 /
lUm*
hte tkreshold current density was as low as 2 KA/cm2. In pulse conditions asymmetric emission properties were detected, as shown in fig.4, with a front to rear power ratio of 2.1, demonstrating good match between DFB emission and DBR reflectivity spectrum. Single longitudinal mode emission at 1.5up to 3 times threshold (6 mW output power) were observed, as shown in fig. 5. The lasing wavelength temperature coefficient and characteristic temperature To were 0.1 nm/deg at 1.2 times
threshold and 53 K,respectively (fig. 6 ) . The large fixed single mode operation range shows that the laser is operating in DR rather than in DBR mode.
Conclusion
A new kind of DSM laser was developed; threshold current as low as 25 mA, asymmetric emission properties and sub-mode suppression ratio of 38 dB at 3 times threshold were recorded.
, DBR j
i Region ;
C
tput / n - I ~ P ~efiession layer n-Passive layer tirat ing
Fig. 1
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Distributed Reflector (DR) laser.-
BIG 1st BIG 2 n d lPhotolithography IIslandI
Etching Ilslandl
Holography
BIG 2nd2
Photolithography IBHI
6ii!si@
Window
BH Etching
Contacts
Fig. 2
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Fabrication Flow-Chart (read by columns).Fig. 3 - Ashing rate of AZ photoresist oxygen pressure = 4*10-2 mbar RF power = 30 W
SPEC- 1edYd.r
*
-BB
1499 prn 1.504 1.509
RES 0.1 nm 1 nmldlv
Fig. 5
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Typical lasing spectrum.References
Fig. 4
-0 50 100 150 Current
I
(mA)-
L-I curve for front-rear emission.2
1.527
-
No L2840-9 Active Region 400pm
-
1.526
-
CW 1/Ith31.2 d-
l-
Active Region 400 sm E1.521
- .-
1.520
-
10
1518 I I I I
,
I260 270 280 290 300 3 0 Temperature (K)
Fig. 6
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Temperature dipendence of lasing spectrum and threshold current.(1) Henry, C.H. : IEEE J. Quantum Electron. QE-21,(1985), 1913 (2) Tohmori, Y.,et al. : Electron. Lett. 21,(1985), 743 (3) Komori, K., et al.:Trans. IEICE of JAPAN E71,(1988), 318 (4) Choi, I.H., et al. : Jpn. J. Appl. Phys., 26,(1987), L1593
