A novel two-section tunable discrete mode Fabry-PÉrot laser exhibiting nanosecond wavelength switching

A novel widely tunable laser diode is proposed and demonstrated. Mode selection occurs by etching perturbing slots into the laser ridge. A two-section device is realized with different slot patterns in each section allowing Vernier tuning. The laser operates at 1.3 mum and achieves a maximum output power of 10 mW. A discontinuous tuning range of 30 nm was achieved with a side mode suppression greater than 30 dB. Wavelength switching times of approximately 1.5 ns between a number of wavelength channels separated by 7 nm have been demonstrated

Highly fabrication tolerant InP based polarization beam splitter based on p-i-n structure

In this work, a novel highly fabrication tolerant polarization beam splitter (PBS) is presented on an InP platform. To achieve the splitting, we combine the Pockels effect and the plasma dispersion effect in a symmetric 1x2 Mach-Zehnder interferometer (MZI). One p-i-n phase shifter of the MZI is driven in forward bias to exploit the plasma dispersion effect and modify the phase of both the TE and TM mode. The other arm of the MZI is driven in reverse bias to exploit the Pockels effect which affects only the TE mode. By adjusting the voltages of the two phase shifters, a different interference condition can be set for the TE and the TM modes thereby splitting them at the output of the MZI. By adjusting the voltages, the very tight fabrication tolerances known for fully passive PBS are eased. The experimental results show that an extinction ratio better than 15 dB and an on-chip loss of 3.5 dB over the full C-band (1530-1565nm) are achieved

1.3 μm wavelength tunable single-mode laser arrays based on slots

Two twelve-channel arrays based on surface-etched slot gratings, one with non-uniformly spaced slots and another with uniformly spaced slots are presented for laser operation in the O-band. A wavelength tuning range greater than 40 nm, with a side-mode suppression ratio (SMSR) > 40 dB over much of this range and output power greater than 20 mW, was obtained for the array with non-uniform slots over a temperature range of 15 °C - 60 °C. The introduction of multiple slot periods, chosen such that there is minimal overlap among the side reflection peaks, is employed to suppress modes lasing one free spectral range (FSR) from the intended wavelength. The tuning range of the array with uniformly spaced slots, on the other hand, was found to be discontinuous due to mode-hopping to modes one FSR away from the intended lasing mode which are not adequately suppressed. Spectral linewidth was found to vary across devices with the lowest measured linewidths in the range of 2 MHz to 4 MHz

Single mode lasers based on slots suitable for photonic integration

The re-growth free single mode lasers based on etched slots suitable for photonic integration are presented in this paper. The fabricated 650?m long laser exhibits a threshold current and a slope efficiency of about 32mA and 0.12mW/mA, respectively. The stable single mode operation has been observed with a side mode suppression ratio (SMSR) over 50dB at a current injection of 100mA for the fabricated laser. Such a laser integrated with electroabsorption (EA) modulator is also demonstrated. The integrated device has an extinction ratio over 10 dB at 2.2V driving voltage with the lasing wavelength of around 20nm positive detuning relative to the gain peak. The bandwidth measured is about 3GHz for the integrated device

Discretely Tunable Semiconductor Lasers Suitable for Photonic Integration

Abstract?A sequence of partially reflective slots etched into an active ridge waveguide of a 1.5 ?m laser structure is found to provide sufficient reflection for lasing. Mirrors based on these reflectors have strong spectral dependence. Two such active mirrors together with an active central section are combined in a Vernier configuration to demonstrate a tunable laser exhibiting 11 discrete modes over a 30 nm tuning range with mode spacing around 400 GHz and side-mode suppression ratio larger than 30 dB. The individual modes can be continuously tuned by up to 1.1 nm by carrier injection and by over 2 nm using thermal effects. These mirrors are suitable as a platform for integration of other optical functions with the laser. This is demonstrated by monolithically integrating a semiconductor optical amplifier with the laser resulting in a maximum channel power of 14.2 dBm from the discrete modes

Compact 2-D FDTD Method Combined With Pad Approximation Transform for Leaky Mode Analysis

Leaky mode analysis has been carried out based on the compact 2-D finite-difference time-domain (FDTD) method combined with the uniaxial anisotropic perfectly matched-layer (UPML) absorption boundary condition and the Pade approximation transform technique. The imaginary part of the effective index of these leaky modes can be calculated independent of the real part, so very small leaky loss can be calculated reliably based on the proposed scheme. Mode coupling effects have also been accounted for naturally within the scheme because the simulation is carried out in the time domain and is full-vectorial. Leaky modes in the ARROW waveguide and the deep ridge waveguide have been analyzed by the proposed scheme. Leakage cancellation behavior for high-order leaky modes in very deeply etched ridge waveguides at specific ridge widths has been observed

Enhancement of quality factor for TE whispering-gallery modes in microcylinder resonators

The enhancement of quality factor for TE whispering-gallery modes is analyzed for three-dimensional microcylinder resonators based on the destructive interference between vertical leakage modes. In the microcylinder resonator, the TE whispering-gallery modes can couple with vertical propagation modes, which results in vertical radiation loss and low quality factors. However, the vertical loss can be canceled by choosing appropriate thickness of the upper cladding layer or radius of the microcylinder. A mode quality factor increase by three orders of magnitude is predicted by finite-difference time-domain simulation. Furthermore, the condition of vertical leakage cancellation is analyzed

Design of Slotted Single-Mode Lasers Suitable for Photonic Integration

A single-mode laser structure suitable for photonic integration is presented. The laser can be fabricated by standard photolithography without any regrowth steps. Through optimization, a threshold current as low as 13 mA and a sidemode suppression ratio (SMSR) up to 47 dB have been predicted for a 400-mu m-long laser. A high yield up to 90% is also predicted with the requirement that the SMSR is higher than 40 dB at an injection current of 100 mA

Linewidth and Threshold Calculations for a Slotted, Fabry-Perot Semiconductor Laser

Abstract-Linewidth and threshold calculations are made for a current-injected, partially ’slotted’ semiconductor laser while including the effects of noise with an explicit derivation of photoncurrent coupling and varying reflectivities as a function of slot depth. Calculations are demonstrated to show good agreement with experiments. I