laser modulators


EML plus locker
Alcatel Optronics has introduced the 1945 LMM 10Gbit/s electro-absorption modulator laser (EML) with a monolithically-integrated wavelength locker for metro DWDM networks. Previous EMLs in metro networks have employed discrete devices for wavelength stabilising and monitoring.

Versatile 40Gbit/s EML
Oki Optical Components' OL5155M EAM monolithically integrates a 1550nm DFB laser and has a good extinction ratio (compared to lithium niobate modulators) for 40Gbit/s OC-768 very short reach (<2km) and NRZ/RZ medium and long-reach transmission.

Oki earlier launched the OM5653C-30B and OM5753C-30B 40Gbit/s EAMs for OC-768 DWDM in metro and long-haul networks.

A new GaInAsP process gives a high-performance, low-power solution which is compact, has a simpler drive design, lower operating voltage of 2.5Vpp, and operates at 40-43Gbit/s (with FEC).

At OFC 2002 Oki launched the OL5150M EML for 10Gbit/s OC-192 up to 40km in metro and intermediate-reach networks. It has dynamic extinction ratio above 10dB and a modulation voltage below 2.5V.

RTD on only 0.1V
Scottish-based start-up Essient Ltd's modulator (to be sampled by end-2002) is based on a resonant tunnelling diode, allowing a drive voltage of just 0.1V. This enables the driver to be integrated with other low-voltage chips in a transceiver module a tenth the size, reducing power consumption and simplifying interfaces for 10 and 40Gbit/s components.

EML comes with integrated driver
At OFC 2002 JDS Uniphase previewed an EML laser with integrated electronic driver. It covers the range of 2.5, 10 and 40Gbit/s modulators, including dual-drive (<3V) Mach-Zehnder modulators for RZ and NRZ long-haul and ultra-long-haul applications with FEC, integrated with a tap/photodiode capable of both bias control and optical power monitoring.

Zero-insertion-loss 10Gbit/s EML for 80-120km
CyOptics has launched an InP-based hybrid electro-absorption modulator with DFB Laser (hybrid EML) for high-bandwidth, external amplitude modulation. It is designed for single-mode light-sources in ONET OC-192/SDH STM-64 transmission systems including DWDM long haul. It combines an EAM and a high-power laser in a low-profile 7-pin butterfly package with GPO connector. Modulation voltage is just 2.5V.

Performance exceeds that of standard monolithic EMLs while maintaining the same size- and pin-compatible package. It can provide 10Gbit/s DWDM or single-channel transmission over 80-120km of standard SMF28 fibre without amplification and dispersion compensation and with <2dB dispersion penalty. In an amplified and compensated link it can transmit to 500km and beyond.

CyOptics' EAM2010 has zero-insertion-loss optical modulation with output power up to 10dBm. Modulated output power exceeds 0dBm. Bandwidth exceeds 12GHz for FEC. Post-amplification is no longer needed and integration of functions eliminates external power monitors and variable optical attenuators.

First wideband InP-based EAM
Qusion Technologies Inc's first product, the InP-based QEM1001 wideband optical modulator, has a 40nm wavelength range covering the entire C band, making it suitable for widely tunable lasers in DWDM. Existing electro-absorption modulators work over 5-15nm.

Qusion has demonstrated a propagation loss of 0.5dB/mm. A high extinction ratio of >20dB enables use for 10Gbit/s transmitters in metro area networks.

InP MZ modulator with DWDM laser
For use in 10Gbit/s regional metro DWDM and long-haul systems, Nortel Networks' LMC10 co-packages a strained-layer (MQW) DFB laser with a InP Mach-Zehnder modulator, locker and variable optical attenuator for the same footprint as the standard 14-pin. Providing LiNbO3 performance at a price similar to EAs, it has a dispersion penalty of <1dB penalty at 1500ps/nm and <2dB at 1800ps/nm, making 110km spans achievable on NDSF.

Widely tunable EML for 2.5Gbit/s metro-core
Agility Communications is producing the widely tunable 4245 EML. Based on its Sampled Grating Distributed Bragg Reflector (SG-DBR) platform, it monolithically integrates an EAM, wavelength locker, modulator driver, control electronics and semiconductor optical amplifier to allow pre-emphasis of output power (eliminating the variable optical attenuator). With the smallest widely tunable transmitter footprint in a 24-pin MSA-compatible package, it is said to cost less than fixed-wavelength or narrowly tunable lasers.

Developed for metro-core DWDM, including one-time provisioning and sparing, dynamic wavelength provisioning, reconfigurable add/drop multiplexers, optical cross-connects and wavelength converters, it also provides greater bandwidth flexibility.

The 4245 supports speeds up to 2.7Gbit/s for FEC and has +3dBm of output power across the full C-band with 50GHz spacing. Low-chirp characteristics enable >200km of dispersion-limited reach over non-dispersion-shifted fibre.

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