InGaAs-InAlAs quantum well intersecting waveguide switch operatingat 1.55 μm

The first electrooptic waveguide switch based on voltage-controlled transfer of electrons into multiple quantum wells is demonstrated. This mechanism is named barrier, reservoir, and quantum well electron transfer (BRAQWET) In GaAs-InAlAs quantum wells it provides a large modulation of refractive index at 1.55 μm with multigigahertz switching capability. The BRAQWET X-switch is free from heating and speed limitations associated with current injection. Beam propagation method (BPM) calculations suggest that the crosstalk performance of this preliminary device demonstration can be significantly enhanced by changes in waveguide geometry     

1.3 μm fluoride fibre laser

Laser action has been achieved in the 1.33-1.34 μm range using an Nd³⁺-doped fluorozirconate glass multimode fibre. These operating wavelengths are the closest to the important telecommunications channel at 1.3 μm of any reported for a glass laser     

1.55 μm wavelength region high-stability optical fibre lossvariation measurement using fibre coupler

A 1.55 μm-wavelength high-stability optical fibre loss variation measurement system, using a comparison method with an optical fibre coupler, was developed. Long-term stability within ±0.001 dB over a 120 hour period at a room temperature variation of ±2.2°C has been achieved     

Pulsed 1.55 μm transmission mode microchip laser usingsemiconductor modulator

A semiconductor saturable absorber modulator is used, for the first time, in a passively Q-switched microchip laser in transmitting mode. The laser has a wavelength of 1.55 μm in a single longitudinal TEM₀₀ mode beam and has pulse characteristics that compare favourably with previously reported data on comparable devices     

Deep sea trial of 1.55 μm optical fibre submarine cable system

The first 6000 m deep sea trial of a 1.55 μm optical fibre submarine cable system was successfully conducted in the Pacific Ocean, near Torishima Island, in January 1988. By using 1.55 μm loss-minimised single-mode fibre cables and submerged fully monolithic Si-IC regenerators with DFB lasers, excellent transmission performances at 140, 280 and 565 Mbit/s were obtained through 150 km repeater spacings, respectively     

Wafer-bonded 1.55 μm vertical cavity laser arrays for wavelengthdivision multiplexing

The first electrically pumped 1.55 μm multiple wavelength VCSEL array is demonstrated. The wafer bonded array consists of four channels operating between 1509 and 1524 nm. Multiple wavelengths were defined using an etched intracavity superlattice prior to bonding. Threshold currents of 0.9 mA and peak output powers of 0.45 mW were measured     

Packaged 1.55 μm DFB laser with 25 GHz modulation bandwidth

25 GHz modulation bandwidth is achieved from a fully packaged 1.55 μm DFB laser, using devices with p-doped compressively strained MQW active regions and large negative wavelength detuning. Devices on submounts show a record bandwidth of 26 GHz, limited by device and bonding parasitics. Resonance frequencies of over 26 GHz are measured     

High-gain, monolithic, cascaded fibre Raman amplifier operating at1.3 μm

A 39 dB-gain silica fibre Raman amplifier is demonstrated at 1.3 μm using a 1064 nm pump. Cascaded Raman generation and amplification are achieved in a monolithic ring cavity constructed solely from conventional fibre components, i.e. fusion WDM couplers and standard silica fibre     

Tunable CW fibre Raman ring laser centred at 1.41 mu m

The first demonstration of a CW tunable fibre Raman ring laser operating around 1.4 mu m is reported. This laser was pumped by a 3 W Nd:YAG laser operating at 1.319 mu m and tuned over a 10 nm range with a maximum output power of 40 mW.<>     

Semiconductor 1.55 μm laser source with gigabit/secondintegrated electroabsorptive modulator

A 1.55 μm laser source with low chirp and high speed can be achieved when a single-mode DFB laser is modulated by an integrated quantum-confined Stark effect electroabsorptive modulator. The dynamic characteristics of such a device are simulated by a time domain, large signal dynamic model. The simulation demonstrates that the frequency chirp has two components: 1) changes of the refractive index induced by variation of the absorption coefficient during the modulation and 2) changes in the lasing frequency caused by changes in the effective residual facet reflection as the external modulator is switched on and off. Optimization by choice of the operating wavelength and coupling coefficient in the lasing section is discussed     

30 GHz bandwidth, 1.55 μm MQW-DFB laser diode based on a newmodulation scheme

The authors present a new concept of modulation for a 1.55 μm DFB MQW laser diode allowing generation of millimetre waves. The method consists in modulating the saturable absorber of a two-section laser. The improvements brought by the new concept are evaluated theoretically and have been verified experimentally for the first time. In particular, a 30 GHz cutoff frequency has been measured     

Continuous wave lasing at 2.7 μm in an erbium-dopedfluorozirconate fibre

A fibre laser operating at 2.702 μm using fluorozirconate fibre doped with <0.1 mol.% of erbium is reported. The authors propose that the mechanism which allows CW operation is absorption of pump radiation by ions in the lower lasing level     

Chromatic dispersion measurement in 1.55 μm narrow-band regionusing a tunable external-cavity laser

Measurement of the chromatic dispersion of an 80.6-km-long, concatenated, dispersion-shifted, single-mode fiber (DSF) with a tunable 1.55-μm external-cavity laser diode, using the phase-shift technique at 1.55 μm over 80-nm bandwidth, is discussed. It is shown that the technique does not need intricate curve-fitting equations or a large number of laser sources with specified wavelengths. As a result, the measurement configuration and procedure are relatively simple. The technique is useful for measuring the chromatic dispersion of future advanced fibers such as dispersion flattened fibers with various refractive index profiles     

Low-noise single-photon detection at wavelength 1.55 μm

The photon-counting performance of commercially available InGaAs/InP avalanche photodiodes operated in Geiger mode was investigated at temperatures between 77 and 260 K. In particular, their noise equivalent power was measured to be 4×10^-17 WHz ^-1/2 at 77 K. The implications of these results in the context of a quantum cryptography application are discussed     

Injection-locked 1.55 μm VCSELs with enhanced spur-free dynamicrange

Injection locking is demonstrated to improve the analogue performance of long wavelength VCSELs. The third-harmonic spur-free dynamic range was improved by 9 dB/Hz^2/3 to be 93 dB/Hz^2/3, and the modulation bandwidth was increased twofold     

Lasing at 2·08 μm and 1·38 μm in a holmiumdoped fluoro-zirconate fibre laser

The authors report for the first time a fibre laser operating beyond the 1·55 μm communications window. Using a holmium doped fluoro-zirconate fibre, laser emission occurs from the three-level 2·08 μm transition, and also at 1·38 μm via a cascading transition     

1-mW CW-RT monolithic VCSEL at 1.55 μm

In this letter, we demonstrate the first result of a high-power (1 mW) continuous-wave room-temperature vertical-cavity surface-emitting laser emitting at 1.55 μm using a single InP substrate. The whole structure was grown monolithically using gas source molecular beam epitaxy and incorporates two original approaches. The first originality consists in the growth of a metamorphic GaAs-AlAs Bragg mirror directly on an InP-based cavity. The second novel idea is to use a tunnel junction for current injection. Moreover by using these two approaches the processing is very simple and, therefore, fulfills the goal for low-cost laser production in access and interconnections applications     

Q-switched operation of laser diode pumped erbium-dopedfluorozirconate fibre laser operating at 2.7 μm

Q-switched operation of a 2.7 μm fluorozirconate fibre laser is shown for the first time. An acousto-optic modulator and a rotating mirror were used as switching elements. Pulse durations of 100 ns and peak powers exceeding 2 W were achieved     

Efficient operation of an Yb-sensitised Er fibre laser at 1.56μm

The authors report operation of a high-efficiency Yb:Er single-mode fibre laser. Pumping at wavelengths of 1064 nm and at 820 nm has shown low pump power thresholds (<7 and 4 mW) and high slope efficiencies (4.2 and 7.0%)     

Neodymium-doped fibre amplifier at 1.064 μm

For the first time, a fibre amplifier with a small signal gain of more than 30 dB at 1.064 μm has been realised. The amplifier employs an Nd-Al codoped fibre and a 0.808 μm pumping laser diode which offers 50 mW incident pump power