Product Focus: lasers

Dec. 1, 2002

Analogue, modulated lasers target cable TV market

Excelight Communications has two new versions of the Sumitomo Electric 5416 direct modulated laser diode module. They have a 14-pin butterfly package with an integrated TEC, built-in optical isolator, and single-mode fibre pigtail. They are available in C-band frequencies at 100GHz channel spacing for cable TV DWDM applications:

  • A new higher-temperature version of the standard SLT5416 for digital return path is directly modulated up to 2.5Gbit/s. The standard laser is suitable up to 1800ps/nm (110km), with extended reach versions for both 2400ps/nm (150km) and 3200ps/nm (200km). Peak power level options include 2, 10, and 20mW.
  • The SLV5416 adds analogue characteristics for QAM narrowcast forward path and QAM trunk line return path applications. It shows good distortion performance when using NTSC 8-channel loading over 40km of standard non-dispersion-shifted SM fibre. Modulated power level options include 6, 8, and 10mW.

Applied Optoelectronics Inc 's 1550nm analogue lasers are optimised for the demanding distortion requirements of CATV.

For forward-path applications, the DFB-1550-BF-XX-A3 series offers up to 13mW of output power in a 14-pin butterfly package. They are designed to carry 77 channels, NTSC; or 60 channels, in PAL-D format.

For the reverse path, the DFB-1550-C5-2-A series of coaxial-packaged lasers features low distortion performance.

JDS Uniphase's CQF 310 is a CW DBR source laser with 20mW output power that is tunable over 24x50GHz (a quarter band).

It is available in eight wavelength ranges covering the C and L bands.

Also, the CQF 478 is a 20mW, 8x50GHz, CW temperature-tunable laser with an integrated etalon-based wavelength locker that can reduce source laser sparing and inventory for metro, hybrid fibre-coax and cable TV applications

Quantum Devices Inc's wavelength selectable laser chip is a high-power monolithic temperature-tunable 1550nm InP 8-element DFB laser array chip. It is integrated with a combiner and a semiconductor laser amplifier.

Output power is >40mW, SMSR >40dB and relative intensity noise (RIN) <-138dB/Hz with a cumulative tuning range of 25nm or 60 ITU wavelengths at 50GHz spacing.

Santur Corp's TL1020-C laser tunes across 36nm (the entire C band) and has the functionality of variable optical attenuation to provide 20mW mode-hop-free without the use of a semiconductor optical amplifier.

The simple design of the DFB array and low-loss coupling scheme enables pure DFB performance.

The module also integrates a wavelength locker for ultra-stable ITU grid operation down to 25GHz channel spacing, and includes built-in control electronics and software for simple interfacing.

Santur has also sampled L-band versions.

Based on its Erbium Micro Fibre (EMF) technology, NP Photonics' SMPF-2030 is a fixed-wavelength fibre laser module with narrow linewidth of <10kHz, mode-hopping free, and an SMSR of >50dB.

Relative intensity noise is <–140dB/Hz at 2MHz. The laser is available at ITU 50GHz for the entire C-band and has wavelength accuracy of ±500MHz.

The module includes embedded microprocessor control and a 1m-long PM fibre pigtail connector with a jacket diameter of 250 or 900µm.

A single-mode diode laser provides the high-reliability pump power of 30mW to drive its erbium-doped micro fibre in a single integrated package of just 168x70x19mm.

NP Photonics will also develop a tunable version for metro

Applied Optoelectronics Inc's cooled 1310nm DFB lasers offer output powers up to 25mW and distortion characteristics of CSO <-57dB, making them suitable for both forward- and return-path CATV applications.

The DFB-1310-BF series has a standard 14-pin butterfly package with OC-48 pin compatibility. Integrated isolators resist signal distortion over links beyond 40km.

For intermediate- and long-reach, digital versions can be directly modulated at 2.5Gbit/s and analogue versions can carry a full channel count in forward-path applications at 50–860MHz.

In Lumics' second-generation LU0980S pump laser chip series, the LU0980S500 provides operating power of up to 500mW (600mW kink-free) and will be used for cooled operation in a standard 14-pin butterfly package. The chip is mounted on a 2x2.3mm ceramic sub-mount.

Forward voltage is only 1.65V at operating conditions (Iop, Top). Threshold current is specified with a maximum of 58mA. Its typical operating forward current is 550mA.

Santec's SweptX swept laser system tunes through 40nm in 2.5s. Precise control of laser wavelength and stability gives a measurement resolution of 1pm. Integrated wavelength and power meters enable speedy and accurate measurement of passive optical component performance.