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A DFB LDM in mini-DIL Packagewith Built-in Thermoelectric Cooler

INTRODUCTION

Data traffic over optical fibers has increased with theexpansion of internet and mobile phone services, anddistributed feedback (DFB) laser diode modules (LDMs)
have been widely applied as the signal source. This LDM
for DWDM, which contains a built-in thermoelectric cooler(TEC), is thought to be more suitable and cost effective
for expanding data channels in the future.
A butterfly-type package with 14-pin layout has been
widely employed for conventional DFB LDMs for DWDM
applications.
On the other hand, optical transceivers and optical
repeater modules for analog applications are highly
required to be small in size, necessitating more compact
signal sources.
We have therefore developed a new DFB laser in amini-DIL package, which has been made suitable for suchmarket demands by incorporating an ultra-compact TEC
into the package. The new mini-DIL DFB LDM has provenits reliability by passing Telcodia GR-468 tests.

2.

FEATURES

Figure 1 shows a comparison between the mini-DIL DFB
LDM and a conventional 14-pin butterfly-packaged DFB
LDM. The mini-DIL LDM measures 7.4 (W)×12.7 (L)×5 (H) mm3, one fifth the volume of conventional modules
and gives the same performance as conventional
LDMs in terms of environmental working conditions,high bandwidth and high output power, with good fiber
coupling efficiency. CuW is used for the bottom plate toachieve better heat dissipation.
Pin assignment is compatible with the Multi-Source
Agreement (MSA) for uncooled lasers, with two additional
pins for the TEC cooler at the back. Interfacing can beachieved not only for pigtailed fiber with any connector
but also for a receptacle type suitable for plug-intransceivers.

3.

PERFORMANCE

3.1 L-I Characteristic
Figure 2 shows the L-I curve for the new mini-DIL DFB
LDMs. LD temperature is kept constant at 25°C by meansof the built-in TEC cooler. Optical output is compatible
with the conventional 14-pin packaged LDMs with a slope
efficiency higher than 0.2 W/A.
Figure 3 shows the temperature dependence of thewavelength. Wavelength drifts no more than ±15 pm
at case temperatures from -50 and 70°C, enabling thismini-DIL DFB LDM to be used in DWDM applications with100-GHz spacing.
3.2

Transmission Characteristics under Direct
Modulation
Eye patterns with and without filtering, and bit error rate(BER) before and after long-reach (160-km) transmission
at 2.5 Gbps under direct modulation are shown in Figures
4 and 5, respectively.

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Comparison between mini-DIL andconventional LDMs.

Figure 2

L-I characteristic of mini-DIL DFB LDM.

Furukawa Review, No. 25

200461

A DFB LDM in mini-DIL Package with Built-in Thermoelectric Cooler�������������� ������� ����������������������������������������������������� ����Figure 3������

Wavelength drift vs. temperature.

Figure 7

3rd order intermodal distortion (IMD3)
characteristics.
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Eye patterns at 2.5 Gbps under direct modulation.

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Results of reliability tests in accordancewith Telcordia GR-468.

�����A good eye pattern with sufficient margin is observed
at a peak output power of 10 mW and an extinction ratioof 10 dB. And the dispersion penalty through the 160-km
fiber demonstrates promising high performance for longreach transmission.

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Figure 5

Bit error rate for back-to-back and160-km data transmission.

3.3 Analog Modulation Characteristics
Relative intensity noise (RIN) and 3rd order intermodal
distortion (IMD3) characteristics are shown in Figures 6
and 7, respectively.
The results show outstanding performance over a wider
bandwidth, providing suitable characteristics for 3rdgeneration mobile phone systems such as IMT-2000.

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RELIABILITY

Long-term tests were carried out in accordance with
Telcordia GR-468, with results that demonstrate highreliability.

Relative intensity noise (RIN) vs. frequency.

Furukawa Review, No. 25

200462

A DFB LDM in mini-DIL Package with Built-in Thermoelectric Cooler

5.

CONCLUSION

We have developed a new type of DFB LDMs in a miniDIL package which can be applied in applications such
as DWDM or mobile phone systems. The new mini-DIL
DFB LDMs will provide customers with high performanceand extra functionality in an ultra-compact configuration.
For more information, please contact:Electronics Sales Department, Sales and Marketing
Division
TEL: +81-3-3286-3150
FAX: +81-3-3286-3978
Semiconductor Devices Development Department,
R&D Division
TEL: +81-436-42-1775
FAX: +81-436-42-1736

Furukawa Review, No. 25

200463