High-frequency optoacoustic transmitter based on nanostructured germanium via metal-assisted chemical etching

Yoo, Geonwook; Park, Youngseo; Sang, Pil Gyu; Baac, Hyoung Won; Heo, Junseok

doi:10.1364/ome.6.002567

Cited by 8 publications

(4 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, if the catalyst consists of dispersed metal particles instead of continuous metal film, formation of porous surface would be unavoidable underneath catalyst region. 33,34 However, platform areas between adjacent inverted pyramids were flat and smooth, indicating no vertical mass transport occurred in metal-covered areas. Thus, the metal layer acted as both etching catalyst and mask, which contributes to the formation of the inverted pyramids and protection of underlying Ge surface beneath the metal, respectively.…”

Section: Macetch Formation Of Ge Inverted Pyramid Arraymentioning

confidence: 99%

A highly ordered and damage-free Ge inverted pyramid array structure for broadband antireflection in the mid-infrared

et al. 2021

View full text Add to dashboard Cite

show abstract

Section: Macetch Formation Of Ge Inverted Pyramid Arraymentioning

confidence: 99%

A highly ordered and damage-free Ge inverted pyramid array structure for broadband antireflection in the mid-infrared

et al. 2021

View full text Add to dashboard Cite

show abstract

“…In an effort to form nanostructured light‐absorbing transmitters, Yoo et al used germanium (Ge) films deposited on quartz substrates . Ge films of different thicknesses (300, 500, and 700 nm) were first deposited by an electron‐beam evaporation process, and then solution‐dispersed gold nanoparticles were spin‐coated over the films.…”

Section: Highly Efficient Photoacoustic Conversion Materialsmentioning

confidence: 99%

Efficient Photoacoustic Conversion in Optical Nanomaterials and Composites

Lee

Baac

et al. 2018

Advanced Optical Materials

Self Cite

View full text Add to dashboard Cite

approaches. While addressing the limitations of the electrical counterparts (e.g., massive amounts of radio frequency (RF) cabling and electromagnetic (EM) interference), a photoacoustic approach for gene rat ing high-amplitude ultrasound has created new opportunities.Active research on efficient photo acoustic materials has started with the development of photoacoustic contrast mediums (e.g., exogenous contrast particles) for contrast enhancement. [3][4][5] Recent advances in nanofabrication technologies have allowed to develop more efficient photoacoustic contrast mediums, [3] such as metal nanoparticles having enhanced optical absorption due to optical resonance. Later, by coating such nanoparticles on a flat substrate, layered structures were developed for generating high-amplitude ultrasound. Among many nanoparticles, gold nanoparticles were widely used owing to strong resonance. [6] In fact, these initial efforts to increase photoacoustic conversion were focused on increasing light absorption, while the critical role of thermal expansion for photoacoustic generation were often overlooked.To enhance thermal expansion for photoacoustic generation, researchers have started to fabricate composite materials, composed of light-absorbing materials mixed with polymers with high thermal expansion coefficients. These polymer-based composites significantly enhance photoacoustic conversion efficiency. Among many polymers, polydimethylsiloxane (PDMS) is exclusively used because of its high thermal expansion, optical transparency, and acoustic impedance comparable to that of water. [7][8][9][10][11] Photoacoustic pulses generated with PDMSbased composites have the characteristics of high amplitude and high frequency, which have enabled interesting applications such as cavitation-based therapy [12] and imaging. [13] For photoacoustic composites, there are a myriad of light-absorbing nanomaterials such as metal absorbers [6] and carbon nanomaterials (e.g., carbon black (CB), [14] carbon nanotube (CNT), [7,10] carbon nanofiber (CNF), [9] candle soot (CS), [8] and reduced graphene oxide (rGO) [15] ). These light-absorbing materials of nanometer sizes have an advantage over microscale absorbing materials [7] in facilitating heat transfer from the light absorbers into the surrounding mediums. Such facilitated heat transfer is another key factor that contributes to photoacoustic energy conversion.In this Review, we will start with general considerations of photoacoustic generation in nanomaterial composites. Various photoacoustic composites enabling interesting applications will be introduced. In addition, recent efforts will be reviewed from an application perspective. Also, we will discuss outlook and future directions.Photoacoustic pulses generated by pulsed laser irradiation have the characteristics of high frequency and wide bandwidth, which are desirable for imaging and sensing. Efficient photoacoustic composites have been developed for fabricating photoacoustic transmitters capable of generating highamplitude ultrasound....

show abstract

“…(iii) The Al states such as the dynamics of temperature and pressure can be studied by heating a submicron Al film with high power nanosecond laser pulses [50]. (iv) Nanostructured germanium (Ge) overlaid with PDMS is fabricated for highly-efficient generation of high-frequency ultrasound [51]. The substrate can be chosen arbitrarily in the fabrication process, allowing flexible applications.…”

Section: Metallic Absorbersmentioning

confidence: 99%

“…(iv) Nanostructured germanium (Ge) overlaid with PDMS is fabricated for highly-efficient generation of high-frequency ultrasound [51]. The substrate can be chosen arbitrarily in the fabrication process, allowing flexible applications.…”

Section: Carbon-based Absorbersmentioning

confidence: 99%

Review of Laser-Generated Ultrasound Transmitters and Their Applications to All-Optical Ultrasound Transducers and Imaging

Chen

2016

Applied Sciences

View full text Add to dashboard Cite

Abstract:Medical ultrasound is an imaging technique that utilizes ultrasonic signals as information carriers, and has wide applications such as seeing internal body structures, finding a source of a disease, and examining pregnant women. The most commonly used ultrasonic transducer today is based on piezoelectricity. The piezoelectric transducer, however, may have a limited bandwidth and insufficient sensitivity for reduced element size. Laser-generated ultrasound (LGUS) technique is an effective way to resolve these issues. The LGUS approach based on photoacoustic effect is able to greatly enhance the bandwidth of ultrasound signals and has the potential for high-resolution imaging. High-amplitude LGUS could also be used for therapy to accomplish high precision surgery without an incision. Furthermore, LGUS in conjunction with optical detection of ultrasound allows all-optical ultrasound imaging (i.e., ultrasound is generated and received optically). The all-optical platform offers unique advantages in providing high-resolution information and in facilitating the construction of miniature probes for endoscopic ultrasound. In this article, a detailed review of the recent development of various LGUS transmitters is presented. In addition, a recent research interest in all-optical ultrasound imaging, as well as its applications, is also discussed.

show abstract

High-frequency optoacoustic transmitter based on nanostructured germanium via metal-assisted chemical etching

Cited by 8 publications

References 17 publications

A highly ordered and damage-free Ge inverted pyramid array structure for broadband antireflection in the mid-infrared

A highly ordered and damage-free Ge inverted pyramid array structure for broadband antireflection in the mid-infrared

Efficient Photoacoustic Conversion in Optical Nanomaterials and Composites

Review of Laser-Generated Ultrasound Transmitters and Their Applications to All-Optical Ultrasound Transducers and Imaging

Contact Info

Product

Resources

About