Photonic Crystal Mirrors Research Articles

CMOS-Compatible Ultra-Compact 1.55- μ m Emitting VCSELs Using Double Photonic Crystal Mirrors

In this letter, the authors report the first demonstration of laser operation in long-wavelength optically-pumped vertical-cavity surface-emitting lasers for photonics-on-complementary metal-oxide-semiconductor back-end integration using 1-D double photonic crystal mirrors. The full exploitation of surface-addressable slow Bloch modes in such photonic architectures promotes an optimized tailoring of light confinement resulting in compact single-mode emitters capable to operate continuous-wave with thresholds in the sub-mW range.

Modulation bandwidth of planar waveguide laser with 1D photonic crystal mirrors

AbstractAn analysis of the 3-dB modulation bandwidth in planar waveguide laser based on 1D photonic crystal structures is presented. The theoretical model takes into account the gain saturation effect, transverse and longitudinal field distribution. A small-signal perturbation solution of the coupled laser rate equation is used to obtain relations describing the dynamic operation. In paper, the distributed Bragg resonator DBR created as 1D photonic crystal is considered. The active waveguide is surrounded by 1D photonic crystal mirrors consisting of alternately placed stripes with different refractive indices. In particular, the influence of the photonic crystal parameters on the 3-dB modulation bandwidth is investigated.

Single layer silicon photonic crystal slab

We present here the fabrication and characterization of single layer silicon photonic crystal mirror on a silicon-on-insulator wafer. By a combination of electron beam lithography, fast atom beam etching with deep reactive ion etching, silicon photonic crystal slabs are achieved on 260nm freestanding silicon membrane and sandwiched with air on the top and bottom. Their high refractive index contrasts enable photonic crystal slabs function as dielectric mirrors for externally incident light. The optical performances of fabricated photonic crystal slabs can be tuned by varying the width of separation grooves or the air-hole size, which represents a significant advantage of offering various approaches for optical response control.

Low-loss optical channel drop filters based on high-contrast Si–air photonic crystals by wet anisotropic etching

Fiber pigtailed optical channel drop filters based on high-contrast silicon (Si)–air photonic crystals (PCs) have been designed and fabricated. A low fiber-to-fiber insertion loss of 2.2 dB is achieved using lensed fiber pigtails inserted into alignment grooves fabricated along with the filter layers that have smooth vertical sidewalls obtained by the high-aspect-ratio crystallographic orientation-dependent wet anisotropic etching of (110) planar Si wafer. Four filters with varying defect widths have been fabricated to drop wavelengths in the 1520–1603 nm range. It is shown that a 2% to 8% change in the periodicity and the associated change in the filling factor introduced in the constituent PC mirrors leads to large photonic bandgaps.

Quasi-3D Light Confinement in Double Photonic Crystal Reflectors VCSELs for CMOS-Compatible Integration

A novel architecture of one-dimensional photonic crystal membrane (PCM) reflectors embodying a heterostructure is proposed as a robust design aimed at a 3-D efficient confinement of light in single-mode polarization-controlled 1.55-μm vertical-cavity surface-emitting laser (VCSEL) microsources for heterogeneous integration on complementary metal-oxide-semiconductor (CMOS). On the basis of a theoretical approach, the paper focuses on the deep interweaving between the kinetics of light transport in the mirrors and the physical nature of the exploited Fano resonances. An example of VCSEL design for optical pumping employing heterostructure-confined photonic crystal mirrors is presented. The predicted photons kinetics along with the considerable improvement in cavity modal features owing to the enhanced mirror architecture have been confirmed by performing rigorous three-dimensional finite-difference time-domain (3-D FDTD) calculations. Finally, experimental observations of photoluminescence (PL) emission performed on first-ever fabricated devices for optical pumping show striking agreement with theoretical considerations and ab initio modelling.

Polarization conversion by a three-dimensional photonic crystal mirror with a diamond structure

We report experimental and numerical studies of a polarization conversion by a three-dimensional photonic crystal. The (001) surface of a photonic crystal with a diamond structure has been shown to act as a mirror-type polarization convertor under normal incidence. When the direction of the incident wave polarization is along [010], the direction of the reflected wave polarization is converted to [100]. This has been found to be due to approximately a half-wave phase shift between the eigenpolarizations of [110] and [1 1¯ 0] upon reflection. This result has been discussed in relation with a polarization-dependent Goos–Haenchen effect.

High-sensitivity temperature sensor based on an alcohol-filled photonic crystal fiber loop mirror

A compact temperature sensor based on a fiber loop mirror (FLM) combined with an alcohol-filled high-birefringence photonic crystal fiber (PCF) is proposed and experimentally demonstrated. The output of the FLM is an interference spectrum with many resonant dips, of which the wavelengths are quite sensitive to the change of the refractive index of the filled alcohol for the interference of the FLM. Simulation analysis predicts a high temperature sensitivity, and experimental results show it reaches up to 6.6 nm/°C for the 6.1-cm-long PCF used in the FLM.

Using penetration depth for phase matching in photonic crystal waveguides

A new method of design for the phase-matching in waveguides is suggested. The approach is based on utilizing the concept of the penetration depth of light into the waveguide walls. The lateral components of wavevectors are employed to adjust the phase-matching condition in the propagation direction. The method is demonstrated in two systems: one using single and the other using double photonic-crystal mirrors.

A one-dimensional photonic-crystal nanocavity incorporating a fluorescent molecular dye

We model the optical properties of a SiN based one-dimensional waveguide photonic crystal nanocavity with three tapered air holes as a function of the photonic crystal mirror fill factor using finite difference time domain calculations. We show that the Q-factor of this type of cavity has a strong dependence on the mirror fill factor, with a Q-factor as high as 35 000 predicted. Experimental studies on a range of representative structures whose surface is coated with a layer of a fluorescent dye confirm our modeling and reveal that such structures are characterized by a single optical mode having a Q-factor of 2000.

Intensity measurement based temperature-independent strain sensor using a highly birefringent photonic crystal fiber loop mirror

A fiber-optic strain sensor is demonstrated by using a short length of highly birefringent photonic crystal fiber (HiBi-PCF) as the sensing element inserted in a fiber loop mirror (FLM). Due to the ultralow thermal sensitivity of the HiBi-PCF, the proposed strain sensor is inherently insensitive to temperature. When a distributed-feedback (DFB) laser passes through the FLM, the output power is only affected by the transmission spectral change of the FLM caused by the strain applied on the HiBi-PCF. Based on intensity measurement, an optical power meter is adequate to deduce the strain information and an expensive optical spectrum analyzer (OSA) would not be needed.

Numerical analysis of mode locking in multi-core photonic crystal fiber

With linearly coupled nonlinear Schrodinger equations, numerical analysis has been performed on the mode locking forming procedure of a fiber laser in the linear cavity configuration. The fiber is Yb-doped multi-core photonic crystal fiber and semiconductor saturable absorber mirror (SESAM) is adopted as the nonlinear transmission element to start mode locking. Because of the noise randomness, initial pulse would be picked out by SESAM in one or more cores which makes the multi-core mode locking quite different from single-core one. The two situations are compared and fully discussed. Mode locking in multi-core photonic crystal fiber laser can be realized only if the couple coefficient between the cores and the temporal overlap between the pulses in different cores are large enough.

Multiwavelength fiber laser based on a photonic crystal fiber loop mirror with cooperative Rayleigh scattering

In this work, a multiwavelength fiber Raman laser based on a highly birefringent photonic crystal fiber loop mirror is presented. A laser resonator is formed when the Raman amplification with cooperative Rayleigh scattering in a dispersion-compensating fiber is used as a distributed mirror and combined with a photonic crystal fiber loop mirror filtering structure. Stable multiwavelength lasing at room temperature is achieved due to the low temperature sensitivity of the highly birefringent photonic crystal fiber.

Performance assessment of hybrid surface emitting lasers with lateral one-dimensional photonic-crystal mirrors

The performance of vertical cavity surface emitting lasers can be enhanced, while simplifying the fabrication process, by adopting a hybrid design using a photonic-crystal (PhC) top mirror. In this paper, we analyze the performance of photonic-crystal surface emitting lasers (PCSELs) by varying the number of periods in the PhC mirror and estimating its reflectivity and lateral radiation losses. We consider three types of PhC mirrors: a simply periodic structure, a structure with a constant period but a variable filling factor (FF), and a structure with a constant FF but a variable period. We show that lateral losses can pose a serious limitation on the minimum size required to achieve an efficient PCSEL operation. We also show that our special structure can convert vertically emitted light into an in-plane light that propagates in the same plane as the PhC mirror creating the possibility of coupling vertically emitted light into optical waveguides. © 2010 Optical Society of America

Photonic crystal cavity embedded barium strontium titanate thin-film rib waveguide prepared by focused ion beam etching

A photonic crystal (PC) cavity embedded Ba 0.7Sr 0.3TiO 3 (barium strontium titanate, or BST) rib waveguide, which functions as an optical filter at λ = 1550 nm, is designed using finite-difference time-domain (FDTD) simulation. The PC cavity is composed of two 5-row photonic crystal mirrors, which are formed by air holes (radii 250 nm) arranged in triangular lattice (periodicity 625 nm) in the BST matrix. Calculations suggested that the required cavity length should be 800 nm for the resonant peak to be situated at 1550 nm. Based on this design, PC cavities were fabricated on BST thin-film rib waveguides by focused ion beam etching with satisfactory results. The transmission spectra of the BST thin-film rib waveguides with PC cavities have been measured. The results agreed well with the FDTD simulation.

Switchable dual-wavelength erbium-doped fiber laser based on the photonic crystal fiber loop mirror and chirped fiber Bragg grating

The switchable dual-wavelength erbium-doped fiber laser (EDFL) with a two-mode photonic crystal fiber (PCF) loop mirror and a chirped fiber Bragg grating (CFBG) at room temperature is proposed and experimentally demonstrated. The two-mode PCF loop mirror is formed by inserting a piece of two-mode PCF into a Sagnac loop mirror, with the air-holes of the PCF intentionally collapsing at the splices. By adjusting the state of the polarization controller (PC) appropriately, the laser can be switched between the stable single- and dual-wavelength operations by means of the polarization hole burning (PHB) and spectral hole burning (SHB) effects.

Demonstration and selection of a single-transverse higher-order-mode beam with radial polarization

Single-transverse higher-order radially polarized beams with multiple rings are selectively generated from a Nd:YAG laser cavity by using a reflectivity-modified and polarization-selective photonic crystal mirror. As predicted by theoretical analysis [A. A. Tovar, J. Opt. Soc. Am. A 15, 2705 (1998)], the intensity distribution and propagation characteristics of the higher-order radially polarized beams are expressed by a Laguerre-Gaussian formula.

Difference between penetration and damping lengths in photonic crystal mirrors

Different mirror geometries in two-dimensional photonic crystal slabs are studied with fully vectorial calculations. We compare their optical properties and, in particular, we show that, for heterostructure mirrors, the penetration length associated with the delay induced by distributed reflection is not correlated with the characteristic damping length of the electromagnetic energy distribution in the mirror. This unexpected result evidences that the usual trade-off between short damping lengths and large penetration lengths that is classically encountered in distributed Bragg reflectors can be overcome with carefully designed photonic crystal structures.

2.6 µm GaSb based photonic crystal coupled cavity lasers

Long wavelength GaInAsSb/AlGaAsSb quantum wells lasers have been grown by molecular beam epitaxy and processed into ridge cavities coupled by an intracavity photonic crystal mirror, to enhance the laser spectral properties. The devices operate in the continuous-wave regime at room temperature with a single frequency emission at 2.6 m.

Performance Investigation of Photonic Crystal-Based Microring Resonator for Optical Signal Processing

A detailed theoretical analysis is presented to characterize wave propagation at 1,550 nm inside a glass (SiO2) microring resonator implemented using photonic crystal technology. A photonic crystal reflection is used at each microring resonator corner to enhance the bending efficiency. The characteristics of both photonic crystal beam splitter and microring resonator bending losses are analyzed and investigated using both effective refractive index and finite difference time domain methods. Analytical expressions are also derived to describe the field enhancement inside the microring resonator, the transfer function of the microring resonator, and the main parameters characterizing the resonator such as resonator band width and quality factor. The analysis is also extended to characterize a drop filter implemented using photonic crystal-based microring resonator. The results indicate clearly that the effective refractive index method can give accurate results if one starts the calculations with finite difference time domain-estimated beam splitter parameters. Further, bending efficiency as high as 99% can be obtained using a ten-post layer photonic crystal mirror at each microring resonator corner.

High-Reflectivity Broadband Photonic Crystal Mirror MEMS Scanner With Low Dependence on Incident Angle and Polarization

In this paper, we introduce a single-axis resonant comb drive highly reflective broadband photonic crystal (PC) mirror microelectromechanical systems (MEMS) scanner with low dependence of reflectivity on incident angle and polarization. Two-dimensional PC mirrors have several advantages over metal coatings and dielectric stacks (1-D PCs) as mirrors. They can tolerate much higher processing temperatures and higher incident powers, as well as operate in more corrosive environments than metals. Compared to multilayer dielectric stacks, 2-D PC mirrors are compact and allow for simpler process integration, making them highly compatible with CMOS and MEMS processing. Our PC mirrors show broadband high reflectivity of > 90% in the wavelength range from 1345 to 1490 nm (> 95% for 1380 to 1450 nm) and very low angular and polarization dependence over this same range. The single-axis MEMS scanners are fabricated on silicon-on-insulator wafers with the PC mirrors fabricated in polysilicon films on oxide. Although the scanner presented in this paper is single axis, the low angular and polarization dependence properties of the 2-D-PC mirror also make it useful for dual-axis scanners. The scanners are actuated by in-chip plane electrostatic combdrives on resonance. Dynamic deflection measurements show that the scanners can achieve 20deg total scan angle with an input square wave of 40 V and up to 120deg total scan angle with 190 V at a resonance frequency of 2.03 kHz. Although the achievable scan ranges are very large, the useful scan angles will be limited by the angular and polarization dependence properties of the PC reflector and its application. For the 2-D PC scanner presented in this paper, applications that can tolerate 10% decrease in reflectivity will have a scan range of 20deg.