Jonathan R. C. Woods, Jon Gorecki, Roman Bek, Stephen C. Richardson, Jake Daykin, Grace Hooper, Emelia Branagan-Harris, Anne C. Tropper, James S. Wilkinson, Mic… 展开作者
Jonathan R. C. Woods, Jon Gorecki, Roman Bek, Stephen C. Richardson, Jake Daykin, Grace Hooper, Emelia Branagan-Harris, Anne C. Tropper, James S. Wilkinson, Michael Jetter, Vasilis Apostolopoulos
Coherent laser arrays compatible with silicon photonics are demonstrated in a waveguide geometry in epitaxially grown semiconductor membrane quantum well lasers transferred on substrates of silicon carbide and oxidised silicon; we record lasing thresholds as low as 60 mW of pump power. We study the emission of single lasers and arrays of lasers in the sub-mm range. We are able to create waveguide laser arrays with modal widths of approximately 5-10 μm separated by 10-20 μm, using real and reciprocal space imaging we study their emission characteristics and find that they maintain their mutual coherence while operating on either single or multiple longitudinal modes per lasing cavity.
We present quantum cascade laser (QCL) frequency comb devices with engineered waveguides for managing the dispersion. The QCL waveguide consists of multiple sections with different waveguide widths. The narrow and wide sections of the waveguide are designed in a way to compensate the group velocity dispersion (GVD) of each other and thereby produce a flat and slightly negative GVD for the QCL. The QCL exhibits continuous comb operation over a large part of the dynamic range of the laser. Strong and narrow-linewidth intermode beatnotes are achieved in more than 300 mA wide operation current ran…
An all-diamond photonic circuit was implemented by integrating a diamond microsphere with a femtosecond-laser-written bulk diamond waveguide. The near surface waveguide was fabricated by exploiting the Type II fabrication method to achieve stress-induced waveguiding. Transverse electrically and transverse magnetically polarized light from a tunable laser operating in the near-infrared region was injected into the diamond waveguide, which when coupled to the diamond microsphere showed whispering-gallery modes with a spacing of 0.33 nm and high-quality factors of 105. By carefully engineering th…
This work represents a particular application of waveguide fabricated by femtosecond laser micromachining technology. More specifically, we report the development of an optical modulator based on the fabrication of single-mode optical waveguide structures buried in X-cut lithium niobate crystal with the femtosecond laser direct writing method. Here, change in refractive index profile is measured using near field intensity profile measurement method at optimized writing conditions. It has been observed that the change refractive index (Δn) is in the range of 10-4. Finally, the behavior of femto…
Tailoring the birefringence of femtosecond-laser-written multi-scan waveguides in glass
Istituto di Fotonica e Nanotecnologie - Consiglio Nazionale delle Ricerche（意大利国家研究委员会光子学与纳米技术研究所）；Dipartimento di Fisica - Politecnico di Milano（米兰理工大学物理系）
We report the first direct femtosecond laser-writing of buried channel waveguides in monocrystalline ZnS. We also report the first single-mode Cr:ZnS depressed cladding buried waveguide laser manufactured by femtosecond laser writing. The laser yields 150 mW average power at 2272 nm wavelength with 11% slope efficiency. A depressed cladding waveguide with propagation loss of 0.62 dB/cm at 1030 nm allowed to obtain spectral broadening under femtosecond-pumping at 1030 nm.
We present an integrated semiconductor-dielectric hybrid dual-frequency laser operating in the 1.5 $μ$m wavelength range for microwave and terahertz (THz) generation. Generating a microwave beat frequency near 11 GHz, we observe a record-narrow intrinsic linewidth as low as about 2 kHz. This is realized by hybrid integration of a single diode amplifier based on indium phosphide (InP) with a long, low-loss silicon nitride (Si$_3$N$_4$) feedback circuit to extend the cavity photon lifetime, resulting in a cavity optical roundtrip length of about 30 cm on a chip. Simultaneous lasing at two freque…
We report the first demonstration of a 1555 nm stepped-height ridge waveguide polarization mode converter monolithically integrated with a side wall grating distributed-feedback (DFB) laser using the identical epitaxial layer scheme. The device shows stable single longitudinal mode (SLM) operation with the output light converted from TE to TM polarization with an efficiency of >94% over a wide range of DFB injection currents (IDFB) from 140 mA to 190 mA. The highest TM mode purity of 98.2% was obtained at IDFB=180 mA. A particular advantage of this device is that only a single step of metalorg…
In this work, a design for a mid-infrared quantum cascade laser (QCL) frequency comb source that enhances the high frequency response and the comb characteristics of the device is presented . A state-of-the-art active region (AR), grown on a heavily n-doped InP:Si substrate, was processed into a buried heterostructure with a microstrip-like line waveguide. As a result, the repetition rate frequency $f_{rep}$, around 11.09 GHz, can be locked to an injected narrow-linewidth radio frequency (RF) signal, over a range of more than 200 kHz with -10 dBm of injected power, which outperforms normal bur…
The equations for the effective medium refractive index and for the confinement factor in the waveguide design for quantum cascade lasers are derived.Compared to equations used in prior literature, by applying rigorous perturbation theory and including the effect of the anisotropic optical gain and non-Hermitian properties of the waveguide structure and materials, a few percent correction should be made to the confinement factor and the effective gain. This result can easily be generalized to any optical devices with a layered structure.
