Single frequency DFB lasers for high resolution spectroscopy

SPECTROCHIMICA ACTA PART A

ELSEVIER

Spectrochimica Acta Part A 52 (1996) 877 879

Single frequency DFB lasers for high resolution spectroscopy V.P. Duraev*, A.V. Melnikov Research and Development Institute POLUS, 3 Vvedensky Street, 117342 Moscow, Russia Accepted 22 December 1995

Abstract

The widespread use of single frequency semi-conductor lasers in molecular spectroscopy stimulated the improvement of single frequency DFB lasers. Here, the results of investigations of DFB lasers with wavelength 1.2-1.55/~m characteristics are reported.

Keywords: DFB lasers; High-resolution spectroscopy

The widespread use of single frequency semiconductor lasers in molecular spectroscopy stimulated the improvement of single frequency DFB lasers. In this report we present the results of investigations of DFB lasers with wavelength 1.2 1.55 /tm characteristics. The DFB lasers were constructed using methods of liquid phase epitaxy (LPE) and metalorganic chemical vapor deposition (MOCVD) growth technique. The active regions of the lasers are multi-quantum-well (MQW) [1]. The M Q W structure of the InGaAsP/

n-lnP

InP tasers is shown in Fig. 1. The structure has four quantum wells [2]. It was grown on the InP-substrate. The grating can be fabricated on the substrate or the second guide layer. For the wavelength of 1.53 m K m the period of the grating was 450 nm (Fig. 2). The stripe structure was fabricated with photolithographic etching. This stripe was buried in semi-insulating InP. The width of the stripe was 2 - 3 /~m (Fig. 3). The output power vs. the injec tion current characteristics and the radiation spectrum on the front and back facets are shown in

InGaAsP(~,=1,25mm)

LJ 4riM r -I

L.~

r2~)nM

p-lnP

\

InxGa1-xAsl~=1,53mm)

Fig. 1. Multiquantum well laser structure (2 = 1.53 /~m). * Corresponding author. Elsevier Science B.V.

PH S0584-8539(96)01667-4

878

V.P. Duraev, A.V. Melnikov /Spectrochimica Acta Part A 52 (1996) 877-879

uSn

n-GalnAsP 1 ~ = = = = ~ , / ' ~ ~ i i i i !~

p-lnP ~ . / . / ~ n-lnP ~ ~-~

/

L

n-GalnAsP ,/

~ GalnAsP

1 /

p-lnP-~

~AuZn Fig. 3. DFB laser (A = 1.53 pm).

%

Fig. 4. The wavelength width of the single frequency lasers was 0.5 A. The temperature wavelength shift AA/AT was less than 0.8 A °C The laser spectrum was investigated for the injection current range 50-120 mA and the temperature range - 1 0 - + 5 0 ° C . For these conditions, single frequency generation was observed.

Fig. 2. Distributed feedback laser structure.

Ppem]

I~o,MKA

2,0

-i 800 700 '600 --

o,5A

1,0

500

400 I

I

1,53mm

ii

300

200

100

50

100

Fig. 4. The output power and spectrum.

[H, mA

v.P. Duraev, A.V. Melnikov / Spectrochimica Acta Part A 52 (1996) 877-879

The investigation of the laser diode was made using a thermocooler. The lasing spectrum was analyzed in a diffraction monochromator. The precision of temperature was 0.01°C: the temperature could change linearly. The intervals of wavelength tuning were 48 A. Laser diodes with 1.53 /lm wavelength were used for spectroscopy and to control the quantity of ammonia vapor in the air. Additionally, the possibility of using semiconductor lasers

879

emitting in the near infrared in high resoltuion spectroscopy and gas analysis were demonstrated.

References [1] V.1. Baryshev, E.G. Golikova and V.P. Duraev, Quantum Electronics, 15 (1988) 2196-2198. [2] E.G. Golikova and V.P. Duraev, Quantum Electronics,22 (1995) 105--107.