160 GHz harmonic mode-locked AlGaInAs 1.55 μm strained quantum-well compound-cavity laser

We characterized the reflectivity and the modal discrimination of intracavity reflectors (ICRs) with different numbers of slots and presented harmonic mode-locking operation of a monolithic semiconductor laser comprising a compound cavity formed by a single deeply etched slot ICR fabricated from 1.55 μm AlGaInAs strained quantum well material. Gaussian pulses were generated at a 161.8 GHz repetition rate with a pulse duration of 1.67 ps and a time-bandwidth product of 0.81.     

Actively mode-locked 1.3 and 1.55 μm InGaAsP diode lasers

Active mode-locking of uncoated InGaAsP diode lasers having an external diffraction grating cavity was investigated experimentally. A high frequency r.f. signal and short-duration electrical pulses were used to drive the lasers. The pulse duration was measured by an ultrafast streak camera. Pulses as short as 13 ps at 1.3m and 29 ps at 1.55m were generated at a repetition rate of 1 GHz. The reason for obtaining broader pulses from the 1.55m laser which had the same structure as the 1.3m diode laser is explained.Formerly with GEC Hirst Research Centre, Wembley, Middlesex, UK.     

High power (130 mW) 40 GHz 1.55 μm mode-locked distributed Bragg reflector lasers with integrated optical amplifiers

High output power 40 GHz 1.55 μm passively mode-locked surface-etched distributed Bragg reflector (DBR) lasers with monolithically integrated semiconductor optical amplifiers are reported. These are based on an optimized AlGaInAs/InP epitaxial structure with a three quantum well active layer and an optical trap layer. The device produces near transform limited Gaussian pulses with a pulse duration of 3.3 ps. An average output power during mode-locked operation of 130 mW was achieved with a corresponding peak power of >1 W.     

1.55 μm AlGaInAs/InP polarization-insensitive optical amplifier with tensile strained wells grown by MOCVD

Polarization-insensitive AlGaInAs'InP semiconductor optical amplifier is realized at wavelength of 1.55 . The active layer consists of three tensile strained wells with strain of 0.40%. The amplifier is fabricated to ridge waveguide structure. The testing result shows the amplifiers have excellent polarization insensitivity (less than 0.8dB). The 1540 nm wavelength optical gain is 20 dB at the bias current of 200 mA.     

InGaAsP/InP 1.55-μm lasers with chemically assisted ion beam-etched facets

Chemically assisted ion beam etching (CAIBE) involving an Ar ion beam and a halogen ambient gas (Cl₂, IBr₃) has been used to etch high-quality laser facets for InGaAsP/InP bulk lasers (1.55 m). We achieved eich rates of 40.0–75.0 nm min^–1 at substrate temperatures between-5 and +10°C. These low temperatures have allowed us to utilize UV-baked photoresists as well as PMMA as etch masks, facilitating very simple process development. Higher substrate temperatures (50 to 120°C) yield still higher etch rates, but at the expense of severely degraded surface morphologies. Angle resolved x-ray photoelectron spectroscopy (XPS) was investigated for observing etched InP surfaces. A disproportioned surface has been detected after etching in the higher temperature range; low temperatures yield stoichiometric surfaces.     

Small-signal modulation characteristics for 1.5 μm lattice-matched InGaNAs/GaAs and InGaAs/InP quantum well lasers

The small-signal modulation characteristics of 1.5 m lattice-matched InGaNAs/GaAs and InGaAs/InP quantum well lasers and their temperature dependence have been calculated. It is found that the maximum bandwidth of the InGaNAs/GaAs quantum well lasers is about 2.3 times larger than that of the InGaAs/InP quantum well lasers due to the high differential gain which results from the large electron effective mass in the dilute nitride system. The slope efficiency for the 3 dB bandwidth as a function of optical density is twice as large for InGaNAs/GaAs as for InGaAs/InP quantum well lasers.     

High performance complex-coupled 1.55 μm distributed feedback lasers for digital transmission

We report low threshold and high speed 1.55 m complex-coupled distributed feedback (CCDFB) lasers with gain coupling induced by a current blocking grating. Excellent device performance has been demonstrated with a record-low threshold of 5.6 mA, a large modulation bandwidth of 11 GHz and useful high temperature operation up to 95°C.     

Noise conversion from pump to the passively mode-locked fiber lasers at 1.5 μm

We characterize the noise conversion from the pump relative intensity noise (RIN) to the RIN and phase noise of passively mode-locked lasers at 1.5 μm. Two mode locking mechanisms, nonlinear polarization rotation (NPR) and semiconductor saturable absorber mirror (SESAM), are compared for noise conversion for the first time. It is found that the RIN and the phase noise of both types of lasers are dominated by the noise converted from the pump RIN and thus, can be predicted with the measured pump RIN and noise conversion ratios. The SESAM laser is found to show an excess noise conversion from the laser RIN to the laser phase noise due to the slow saturable absorber effect.     

1.55-μm InGaAs/InGaAlAs MQW vertical-cavity surface-emitting lasers with InGaAlAs/InP distributed Bragg reflectors

High-performance InGaAs/InGaAlAs multiple-quantum-well vertical-cavity surface-emitting lasers (VCSELs) with InGaAlAs/InP distributed Bragg reflectors are proposed for operation at the wavelength of . The lasers have good heat diffusion characteristic, large index contrast in DBRs, and weak temperature sensitivity. They could be fabricated either by metal-organic chemical vapor deposition (MOCVD) or by molecular beam epitaxy (MBE) growth. The laser light-current characteristics indicate that a suitable reflectivity of the DBR on the light output side in a laser makes its output power increase greatly and its lasing threshold current reduce significantly, and that a small VCSEL could output the power around its maximum for the output mirror at the reflectivity varying in a broader range than a large VCSEL does.     

High efficiency cw far infrared lasers at 119 μm and 127 μm

The optically pumped FIR laser lines at 119 m from CH₃OH and at 127 m from¹³CD₃OH are known to be the most powerful in the far infrared spectral region. We report on efficiency measurements for our waveguide laser system. The effect of various parameters was investigated, resulting in the highest efficiency ever reported for the 119 m line. The Stark effect and others parameters of the 127 m were measured, and a new¹³CD₃OH laser line at 175 m discovered, with the same pump transition. These measurements are helpful for completing the assignment already proposed for the 127 m line.     

1.55μm InGaAsP/InP LED的研究

本文报导了1.55μm InGaAsP/InP LED的制造工艺和性能测量.在100mA正向电流下,LED与多模光纤和单模光纤耦合后的出纤功率分别为20～30μW和2—4μW.讨论了获得准确p-n结位置的方法.     

Fabrication and Performance of 1.55 μ/m Transmission Glass-Echelon Grating Filters

This paper describes the fabrication method and the measured spectral behavior of a 1.55 μm transmission glass-echelon grating filter. This echelon grating consists of a pile of identical plane-parallel glass plates constructed using a special assembling tool. The experimental result confirmed the accuracy of the Fourier transform which indicated that the spectral passband width was inversely proportional to the beam size. This feature makes it possible to use the filter as a bandpass filter or a comb filter when constructing photonic networks. The echelon filter has certain intrinsic advantages including a low insertion loss and polarization independence. Moreover, it offers good cost performance and excellent design flexibility.     

1.56 μm and 2.86 μm Raman lasers based on gas-filled anti-resonance hollow-core fiber

We report here a single-pass 1.56 μm fiber gas Raman laser in a deuterium-filled hollow-core fiber and a 2.86 μm cascade fiber gas Raman laser with methane in the second stage. The maximum output powers at 1.56 and 2.86 μm are 27 and 8.5 m W with Raman conversion efficiency of 30% and 42%, respectively. The results offer a new method to produce a 1.5 μm fiber source and prove the potential of the cascade fiber gas Raman laser in extending the available wavelength.     

Missing modes in 1.3 μm InGaAsP/InP uncooled Fabry–Perot lasers and their effect on transmission performance

We report mode missing and modal instability of uncooled Fabry–Perot (FP) lasers for the temperature range from –45 to 85C and their effect on transmission performance. Using the time domain laser model (TDLM), mode missing has been modeled in FP lasers with structural defects in the active layer. Using this model, we have estimated eye opening penalty (EOP) due to missing modes up to 2.5 Gbps data rate. These simulation results suggest that FP lasers should have less than two missing modes for stable operation and high performance for optical data links.     

Highly birefringent photonic crystal fiber with low confinement loss at wavelength 1.55 μm

High birefringent and low confinement loss of photonic crystal fiber is reported at wavelength 1.55 μm via Full-Vectorial Finite Element Method (FV-FEM). By suitable designing of three ring hexagonal solid core fiber and also by introducing a pair of large holes along x-axis near the core region, high modal birefringence 3 × 10⁻³ and low confinement loss 0.019 dB/km are found at wavelength 1.55 μm.     

InP-based 1.3/1.55 μm wavelength demultiplexer with multimode interference and chirped grating

We propose a novel 1.3/1.55 m wavelength demultiplexer for integration with lasers and detectors on the InP material system. A chirp grating is placed inside a multimode interference (MMI) structure to shorten the device length and increase wavelength tolerance. The simulation using the bi-directional beam propagation method proves that the demultiplexer can have very low insertion loss and high isolation ratio. The approach of grating fabrication is also described.     

Reduction of the threshold temperature sensitivity of 1.55 μm InGaAsP lasers by subnanosecond optical excitation

In GaAsP lasers operating at 1.5 to 1.6 m were pumped optically with a pulsed 1.06 m source. The temperature dependence of the pump energy at laser threshold has been measured for temperatures from 170 to 330 K. Pump pulse widths of 300 ns and 150–300 ps were employed, long and short compared to the carrier life-time in the laser material. Over the high-temperature range of 260 to 330 K short pulse excitation gives a considerable reduction of the threshold temperature sensitivity with a characteristic temperatureT ₀ =85 K compared to T ₀ ^h =45 K for long-pulse excitation. This is in qualitative agreement with previous results on electrically excited lasers although the temperature sensitivity of the optically excited lasers is larger. At temperatures between 170 to 260 K no reduction of the temperature sensitivity was observed.     

High peak power 1.0 μm and tri-wavelength 1.3 μm Nd:ScYSiO_5 crystal lasers

With a Nd:ScYSiO_5 crystal, a high peak power electro-optically Q-switched 1.0 μm laser and tri-wavelength laser operations at the 1.3 μm band are both investigated. With a rubidium titanyle phosphate(RTP) electro-optical switcher and a polarization beam splitter, a high signal-to-noise ratio 1.0 μm laser is obtained, generating a shortest pulse width of 30 ns, a highest pulse energy of 0.765 mJ, and a maximum peak power of 25.5 kW,respectively. The laser mode at the highest laser energy level is the TEM200 mode with the Mvalue in the X and Y directions to be M_x~2= 1.52 and M_y~2= 1.54. A tri-wavelength Nd:ScYSiO_5 crystal laser at 1.3 μm is also investigated. A maximum tri-wavelength output power is 1.03 W under the absorbed pump power of7 W, corresponding to a slope efficiency of 14.8%. The properties of the output wavelength are fully studied under different absorbed pump power.     

Modeling of InGaAsP–InP 1.55 μm lasers with integrated mode expanders using fiber-matched leaky waveguides

A new concept for InGaAsP–InP 1.55 μm lasers integrated with spot size converters using leaky waveguides is presented. The large fundamental mode size and the high discrimination of the higher order modes make ARROWs (Antiresonant Reflecting Optical Waveguides) and antiguided waveguides useful for fiber coupling functions. Three-dimensional (3-D) beam propagation method (BPM) results show that the devices have transformation losses lower than 0.22 dB. Fiber-coupling efficiencies of 60% are possible with standard cleaved single-mode fibers (SMF). The horizontal and vertical FWHM can be efficiently reduced to 9.70° (horizontal) and 17.80° (vertical). The fabrication of such devices avoids the growth of thick layers of quaternary material with a low Ga and As fraction, and simplifies the fabrication to one planar epitaxial growth step and one non-critical conventional etch. Received: 16 May 2001 / Published online: 30 October 2001     

A novel coupled quantum well structure with large field-induced refractive index change and low absorption loss at 1.55 μm

In future networks, very-high-speed and high-capacity di-rect optical switching systems will play a very importantrole, and an optical switching device is considered to be akey device for the construction of such high-speed opticalswitching systems or photonic integrated circuits[1]. Soit is imperative for optical switching device to search fora material with high-speed and large field-induced re-fractive index change in the case of low absorption loss.It is well known that a large electric fi…