Oki Develops DFB Laser With Integrated EA Modulator For 40 Gb/s High-Speed Optical Communications
March 15, 2001, Tokyo, Japan -- Oki Electric Industry Co., Ltd. announced
today that it has developed a semiconductor laser with an integrated electro-absorption
(EA) modulator, an optical device that uses the electro-absorption effect of a
semiconductor to provide high-speed modulation of a laser light, for 40 Gb/s optical
communications.
Oki Electric plans to begin shipping the new device in sample quantities in
October 2001.
There has been a strong need for the integration of EA modulators and lasers,
since optical couplings between the discrete modulator and laser degrade the light
output power. The new product consists of a 40 Gb/s EA modulator in a monolithic
integration with a DFB semiconductor laser light source*1,
resulting in more compact and less power-consuming optical sources for 40 Gb/s
operations.
The rapid growth of the IT industry has stimulated the demand for high-capacity
optical communications that can rapidly transfer large quantities of information.
Currently, 10 Gb/s optical communications systems are being used as backbone optical
networks, and 40 Gb/s optical systems are expected in one or two years. Oki Electric's
discrete EA modulator, which uses InP/InGaAsP and owned ridge waveguide structure*2,
boast superior high-speed modulation. Oki Electric's discrete EA modulator, the
first to support 40 GHz bandwidth, is under sample shipping prior to the other
competitors. And this time, Oki has succeeded to integrate a DFB laser with the
40Gb/s EA modulator.
Product Overview
A 40 Gb/s modulation requires reduced capacitance of the EA modulator. Oki
Electric, by utilizing its ridge waveguide structure and by reducing the length
of the EA modulator to 100 microns, has achieved a reduction of a capacitance.
In general, there is a tradeoff between the capacitance and the modulator extinction
ratio (the ratio of transmittance between its "on" and "off" conditions), since
a decrease in the modulator length to reduce the capacitance increases the difficulty
of achieving a practical extinction ratio. To solve this problem in its new product,
Oki Electric optimized the detuning wavelength between the laser and EA modulator
by adjusting the composition of the InGaAsP quantum absorption layer.e As
a result, the dynamic extinction ratio larger than 10 dB (=12 dB) has been achieved
for the first time with the 40 Gb/s EA modulator-integrated DFB lasers.
- Modulation bandwidth: 41GHz
- Dynamic extinction ratio: 12dB (at 3V)
- Output wavelength: 1550nm
- Optical output: +8dBm (under CW operation)
Details of the development are scheduled to be announced in a presentation (paper
no. MJ-3 by invitation) at Optical Fiber Communications 2001 (OFC 2001) from March
17 to 22 in Anaheim, California. OFC 2001 is the world's most authoritative international
conference regarding optical communications.
Notes:
*1 DFB laser
A Distributed Feedback laser. A DFB laser has a relatively wide spectrum, and
many resonant modes within that spectrum, making it tend toward multi-longitudinal
mode oscillation. In the DFB laser, the fine pitch grating is fabricated in the
laser cavity to select one of these resonant mode to result in lasing operation
with one particular longitudinal mode.
*2 Ridge waveguide structure
A kind of waveguide structures which are used to confine the optical beams in
restricted area. There are two types of waveguides used frequently: one is buried
heterostructure waveguide and the other is ridge waveguide. Ridge waveguide is
preferable to achieve the lower capacitance, although it requires more strict
fabrication tolerances.
About Oki Electric Industry Co., Ltd.
Founded more than a century ago in 1881, Oki Electric Industry Co., Ltd. is Japan's
first telecommunications manufacturer headquartered in Tokyo, Japan. With more
than 21,000 employees worldwide, Oki Electric provides customers with top-notch
products and technologies for telecommunication systems, information systems and
electronic devices.
Press Contact:
Public Relations Division
Phone: +81-3-3580-8950 |
|
