Summary form only given. Transparent ceramics are promising materials for solid-state lasers because of their size-scalable synthesis method, high optical quality and similar spectroscopic properties ...as compared to their single-crystal counterparts. In particular, the Lu 3 Al 5 O 12 (LuAG) garnet is attractive for the fabrication of transparent ceramics due to its excellent thermal properties 1. Due to the closeness of ionic radii of Lu 3+ and Tm 3+ , LuAG ceramic is attractive for hosting tulium (Tm 3+ ) ions which are known for its eye-safe laser emission at ~2 μm (the 3 F 4 → 3 H 6 transition). Moreover, in garnets, the Tm 3+ emission typically occurs above 2 μm which is relevant to mode-locking of femtosecond lasers 2. Here, we report on the synthesis, spectroscopy, efficient continuous-wave (CW) and passively Q-switched (PQS) laser operation of Tm:LuAG transparent ceramics. They were fabricated by solid-state reactive sintering at 1830 °C of Lu 2 O 3 , α-Al 2 O 3 and Tm 2 O 3 powders, with MgO and TEOS as sintering aids. A SEM image of the ceramic fractured surface shows clear grain boundaries and uniform grain size distribution (mean size: 21 μm), Fig. 1(a). The absorption, and stimulated-emission (SE), USE, cross -sections for the 3 H 6 ↔ 3 F 4 transition are shown in Fig. 1(b). In the long wavelength part of the SE spectrum, USE = 0.11 x10 20 cm 2 at 2021 nm. The measured lifetime of the 3 F 4 state num is 9.68 ms, Fig. 2(c). The transition intensities for Tm 3+ were also determined within the Judd-Ofelt theory
We report on inkjet-printing of graphene saturable absorbers (SAs) suitable for passive Q-switching of ~2-μm bulk and waveguide lasers. Using graphene-SA in a microchip Tm:KLu(WO 4 ) 2 laser, 1.2 ...μJ/136 ns pulses are generated at 1917 nm.
Summary form only given. Complex tungstate and molybdate crystals are known as excellent host materials for doping with trivalent rare-earth ions RE 3 +, e.g. Yb 3 + or Tm 3 +, 1 and they are ...Raman-active. Due to the structure features, they offer high RE 3 + doping levels, low non-radiative relaxation rates, weak concentration quenching, and broad and intense spectral bands of the RE 3+ ions in polarized light. Lithium metal molybdate crystals with the lyonsite structure, Li 2 M 2 (MoO 4 ) 3 where M 2 + = Mg, Zn, Mn, Ni, etc. (shortly LiMMo) 2 have been poorly studied as laser host matrices. In the present paper, we report on the growth, structure, vibronic, thermal and spectroscopic properties of Yb:LiMgMo and Yb:LiZnMo single-crystals showing high potential for broadly tunable and sub-100 fs mode-locked lasers at ~1 μm.
Summary form only given. Ytterbium (Yb 3+ ) doped solid state materials are well-known for highly-efficient and wavelength-tunable laser operation at μm. The search for novel host matrices for Yb 3+ ...doping which can simultaneously provide intense, smooth and broad spectral bands and attractive thermal properties is of high importance for power-scalable, tunable lasers and ultrafast oscillators and amplifiers. Disordered trigonal langasite-type crystals have been known for a long time due to their attractive thermo-mechanical properties and the suitability for rare-earth (RE 3+ ) doping 1. Recently, the calcium niobium gallium silicate, Ca 3 NbGa 3 Si 2 O 12 (CNGS), has been studied as a laser host for Nd 3+ ions 2. In this work, we report on the growth, spectroscopy and efficient continuous-wave (CW) and passively Q-switched (PQS) laser operation of Yb:CNGS.
Summary form only given. The eye-safe Thulium (Tm 3 +) laser emission at ~2 μm, based on the 3 F4 → 3 H 6 transition, is of interest for remote sensing and medicine. Monoclinic double tungstates are ...known as excellent hosts for Tm + ions allowing for efficient lasers at ~1.94 μm 1. However, they suffer from low thermal conductivity (~3 W/mK) limiting the power scaling. Recently, another monoclinic tungstate crystal with a wolframite structure, MgWO 4 which exhibits much better thermal properties has been proposed for RE 3 + doping 2. In the present work, we report on efficient and compact Tm:MgWO 4 lasers at >2 μm.
Passively mode-locked femtosecond Tm:MgWO4 laser Yicheng Wang; Weidong Chen; Lizhen Zhang ...
2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC),
2017-June
Conference Proceeding
Summary form only given. Femtosecond mode-locked lasers near 2 μm based on the Tm 3+ ion have been drawing great attention since they are applied in various fields including physics, chemistry and ...biology 1. Among the host materials for Tm 3+ , the monoclinic double tungstate crystals are one of the most promising for ultrashort pulse generation 2. Recently, we successfully demonstrated efficient laser operation of a new monoclinic divalent metal monotungstate, Tm 3+ :MgWO 4 , crystal 3. Due to the low-symmetry structure and the distortion of the rare-earth site caused by the mismatch of the ionic radii of Mg 2+ and Tm 3+ , the absorption and emission bands of Tm:MgWO 4 are rather broad. Motivated by these attractive spectroscopic properties, we study here mode-locked laser operation of Tm:MgWO 4 using a single-walled carbon nanotube (SWCNT) based saturable absorber (SA) in the present work.
A multi-layer MoS 2 -based saturable absorber enables Q-switched operation of Yb and Tm:KLu(WO 4 ) 2 microchip lasers. The Tm laser generated 1.27 W with 175 ns/7.5 μJ pulses at 1929 nm and a slope ...efficiency of 43%.
Summary form only given. Lasers emitting around 2 μm (eye-safe spectral range) are of practical importance for remote sensing, spectroscopy and medicine. Such emission is typically achieved from Tm ...3+ ( 3 F 4 → 3 H 6 transition) and Ho 3+ ions ( 5 I 7 → 5 I 8 transition). The search for appropriate saturable absorbers (SAs) for passive Q-switching (PQS) of ~2 μm lasers is still ongoing. While "slow" SAs, e.g. Cr 2+ :ZnS, are well-established, "fast" SAs for high-repetition-rate (MHz-range) PQS or mode-locking are still under investigation. The technology of semiconductor saturable absorbers (SESAs) at ~2 μm is far from being mature. In the present work, we studied the potential of carbon nanostructures (single-walled carbon nanotubes, SWCNTs, 1 and graphene) as possible alternatives to SESAs.
Background: Cell-free DNA (cfDNA) concentrations have been described to be inversely correlated with prognosis in cancer. Mutations in HCC-associated driver genes in cfDNA have been reported, but ...their relation with patient’s outcome has not been described. Our aim was to elucidate whether mutations found in cfDNA could be representative from those present in HCC tissue, providing the rationale to use the cfDNA to monitor HCC. Methods: Tumoral tissue, paired nontumor adjacent tissue and blood samples were collected from 30 HCC patients undergoing curative therapies. Deep sequencing targeting HCC driver genes was performed. Results: Patients with more than 2 ng/µL of cfDNA at diagnosis had higher mortality (mean OS 24.6 vs. 31.87 months, p = 0.01) (AUC = 0.782). Subjects who died during follow-up, had a significantly higher number of mutated genes (p = 0.015) and number of mutations (p = 0.015) on cfDNA. Number of mutated genes (p = 0.001), detected mutations (p = 0.001) in cfDNA and ratio (number of mutations/cfDNA) (p = 0.003) were significantly associated with recurrence. However, patients with a ratio (number of mutations/cfDNA) above 6 (long-rank p = 0.0003) presented a higher risk of recurrence than those with a ratio under 6. Detection of more than four mutations in cfDNA correlated with higher risk of death (long-rank p = 0.042). Conclusions: In summary, cfDNA and detection of prevalent HCC mutations could have prognostic implications in early-stage HCC patients
Abstract only
2557
Background: The development of human intratumoral therapy (HIT-IT) has surged as a promising strategy to overcome resistance to checkpoint inhibitors (CPI), promoting a stronger ...tumor-specific immune response while reducing systemic exposure. A broad variety of agents (i.e: oncolytic viruses, toll-like receptors agonists) administered both in superficial- and deep-seated lesions are being currently tested in clinical trials (CT). Due to the local intervention on tumors, radiological assessment by standard RECIST is challenging and new methods of response that capture and integrate the local and systemic response to HIT-IT are needed. We aimed to evaluate the feasibility and clinical utility of itRECIST (Goldmacher et al., 2020) in patients (pts) treated with HIT-IT in early phase CT. Methods: Retrospective analysis of a cohort of pts with different solid tumor types enrolled in CT including HIT-IT in our institution between August’18 and January’21. Clinical characteristics were collected. Efficacy in target-injected (T-I) and target-non-injected (T-NI) lesions was assessed by objective response rate (ORR) and disease control rate (DCR), as per itRECIST. Overall disease ORR and DCR were assessed per RECIST 1.1/iRECIST. Treatment-related adverse events (TRAEs) were assessed with CTCAE v.5.0. ORR was calculated with Clopper-Pearson method. Survival analysis was made using Kaplan-Meier method. Results: A total of 37 pts were included. Median age was 66 years, 19 pts (51%) were male, all pts had ECOG 0-1. 24 pts (65%) were CPI-naïve. Median previous lines of therapy was 2 (range r: 0-11). All pts (100%) received minimum 1 dose of HIT-IT. 6 pts (16%) were treated with monotherapy and 31 pts (84%) in combination with CPI. Median HIT-IT and CPI doses administered were 4 (r: 1-9) and 2 (r: 1-13), respectively. Injected lesions: cutaneous (16.2%), subcutaneous (21.6%), lymph node (32.4%), liver (29.7%). Median size of T-I lesions was 40 mm (r: 19-260). At data cutoff, 32 pts were evaluable. Median follow-up was 14.4 weeks (r: 1.0-81.1). Per RECIST 1.1, overall ORR was 6% (95% CI, 5-7) and DCR was 38% (95% CI, 21-56). Per itRECIST, ORR was 19% (95% CI, 7-36) and DCR was 63% (95% CI, 44-79) in T-I lesions (n = 32), and 10% (95% CI, 22-27) and 48% (95% CI, 29-67) in T-NI lesions (n = 29). Mean decrease in responding T-I and T-NI lesions was -47% (r: -21 to -100) and -41% (r: -26 to -59), respectively. No non-target (NT) lesion was injected. Median progression-free survival was 7.4 weeks (95% CI, 6.6 – 8.2). Median overall survival was 10.0 months (95% CI, 2.3 – 17.7). Incidence of TRAE was 58% (grade 1-2 IT-related pyrexia 43%; grade 3-4, 5%). No treatment-related deaths were recorded. Conclusions: ItRECIST is feasible to implement and adds precision to the radiological assessment of local and distant anti-tumor activity of HIT-IT. No safety issues were detected in our cohort.
